Publications using or mentioning FLEC^®

A five-year study of VOC emissions from PVC flooring installed on concrete under different moisture and alkalinity conditions. Surface-emission samples were collected with the Field and Laboratory Emission Cell (FLEC) method for comparison with bulk VOC measurements.

The study develops a staged approach to chemical hazard assessment for reused concrete products in indoor environments. It explicitly discusses FLEC surface-emission measurements as a quantitative method for determining surface VOC emission rates in field conditions.

This review compares methods for sampling and assessing VOC emissions from engineered wood products. It explicitly covers the Field and Laboratory Emission Cell (FLEC), including its standardisation, strengths, limitations and correlation with chamber methods.

An in-situ cylindrical sampling chamber is introduced for determining solid–gas interface concentrations of volatile organic compounds from building materials. The method is evaluated through flow-field analysis, chamber tests and a field demonstration, and the article cites the Field and Laboratory Emission Cell (FLEC) as an established emission-cell method.

A review of methods for sampling VOC emissions from consumer products. It contains a dedicated section on the Field and Laboratory Emission Cell (FLEC), describing its construction, operation and suitability for non-destructive in-situ sampling.

The article assesses ozone removal and primary and secondary emissions from indoor coatings. Its discussion of earlier test methods explicitly identifies the Field and Laboratory Emission Cell (FLEC) and compares FLEC-derived results with larger chambers.

Surface emissions in a test house were measured with a flux chamber coupled to PTR-MS and compared with whole-house VOC emissions. The paper discusses the Field and Laboratory Emission Cell (FLEC) as an established approach for surface emission measurements.

Building materials are the major sources of Volatile and Semi-Volatile Organic Compounds (VOCs and SVOCs) in indoor air. Measurements of emission rates of these compounds are likely to be influenced by variation in certain environmental factors resulting in intra-specimen variability. This study aims to (i) evaluate the reproducibility of measurements between specimens and (ii) evaluate the impact of storage on VOC and SVOC emissions from antifungal acrylic paint (applied on polyester-cellulose). For this purpose, 15 discs of tested materials (1.63 ± 0.04 g) were prepared. From these, the emissions rates (ER) of 5 samples were analyzed simultaneously during three measurement campaigns (October 2021, January 2022 and March 2022). Between each campaign, specimens were stored in the dark at ambient temperature (25 ± 4 °C) and relative humidity (50 ± 20 %). Measurements were performed using the field and laboratory emission cell (FLEC) and characterized by gas chromatography (TD-GC-MS/FID) and liquid chromatography (HPLC). Intra-specimen reproducibility was assessed by comparing 5 ER of different specimens collected simultaneously. The impact of storage was evaluated by comparing the average VOC/SVOC ER between each campaign. The results show, concerning the reproducibility of the measurements, that the first measurement campaign provides ER with high variability (10 – 36 %) compared to the second and third measurement campaigns, which show lower intra-specimen variability (5 – 24 % and 8 – 20 % respectively). However, weakly emitted compounds (ER < 10 μg m-2 h-1) such as aromatics and aldehydes show large variabilities (6 – 100 % of variation) in all measurement campaigns. Regarding the effect of the 5-months storage a significant decrease in the ER of individual VOC/SVOCs (37 – 85 %) and of TVOCs (74 %) was noted, except for aldehydes, aromatic hydrocarbons, isopropylacetone and vinyl crotonate, which showed a stability or eventual increase (up to 100 %) in the ER over time, depending on the type of emitted compound.

In the recent years, there has been an increased interest in indoor air quality in heritage environments, specifically in relation to volatile organic compounds (VOCs). These could originate from objects, furnishings, visitors and staff, as well as from olfactory exhibitions. This interest led to a number of studies investigating the “typical” emissions for diverse materials and their impact on the surrounding environment. The analysis of volatile compounds emitted by objects helps in the characterization of the material composition, its conservation history or its degradation processes. This contribution reviews how volatiles are emitted from objects and the commonly used sampling techniques for heritage science applications. A variety of methods are available, from bulk air sample collection to preconcentration using samplers. The commonly studied object types contributing to indoor VOCs are discussed. These include emissions from heritage objects, conservation products, furnishing materials and display cases. Furthermore, olfactory exhibitions are discussed in terms of indoor air quality. Finally, the findings are compared with the current guidelines on indoor volatile concentrations.

Inorganic construction materials are chiefly envisaged as structural materials. However, they provide unexplored interfaces with characteristic surface chemistry to interact with indoor gases. This work proposes for the first time an insight on uptake abilities of lime-cement-plaster toward indoor pollutant. Because of toxicity and regulation policies, formaldehyde is selected as representative indoor pollutant. This work explores gas-material interaction to elucidate fate of formaldehyde onto lime-cement-plaster and addresses air quality impact. Uptake and fate of formaldehyde onto plaster is addressed using Field and Laboratory Emission Cell coupled with SIFT Mass Spectrometer. The experimental sequence is continuously deployed on 90 days to address realistic and long-term behaviour of formaldehyde uptake. Experimental approach evidences that from 65 to 77% of formaldehyde inlet concentration is continuously taken up on plaster samples throughout experimental sequence. Concomitantly, methanol is observed showing the reactivity of formaldehyde uptake on this material-class. Diffuse Reflectance Infrared Spectroscopy evidences that formaldehyde undergoes heterogeneous Cannizzaro reaction on the plaster surface. This surface reaction proceeds with adsorbed formaldehyde, even in the absence of gaseous pollutant supply. The quantitative balance of the disproportionation process is proposed along the experimental sequence to clarify the fate of formaldehyde encompassing gaseous and adsorbed-phase. The evidenced surface process can impact formaldehyde budget in indoor air, thus relevant parameters are determined to allow further implementation of this reactive contribution to indoor air quality models. This work settles perspectives for passive mitigation of indoor formaldehyde, and points at the need to address reaction products for their indoor air quality impact.

The use of bio-based insulation materials is widely spreading in buildings. Due to their organic load, they can be an important source of Volatile Organic Compounds (VOCs). This study is among the first that evaluates the spatial and seasonal in-field VOC surface emissions from bio-based and conventional building structures as a whole, in a French public building insulated with wood wool. In addition to surface emissions, measurements of VOC concentrations in indoor air were taken. Results showed that a spatial difference (up to 5 times) in VOC emissions was observed due to the inhomogeneity of the surface. Moreover, the cardinal orientation of building structures with the same constitution induced a difference (up to a factor 30) in emission rates due to the exposure to different hygrothermal conditions. The variation in temperature and relative humidity between seasons led to higher summer VOC emissions and indoor air concentrations. In addition, indoor VOC concentrations were shown to be higher at night compared to daytime due to the decreased ventilation rate. Furthermore, an interesting approach was developed in this study to have a primary overview of the impact of surface emissions on indoor VOC levels. Results confirmed that the three bio-based walls have no significant specific VOC emissions at high rates compared to the floor and the ceiling. Bio-based insulations showed no impact on microbial indoor air concentrations during the two seasons. Moreover, no detected VOCs could be attributed to microbial development as they were also emitted from building materials.

A membrane-based enthalpy exchanger is a device used for heat and humidity recovery in ventilated buildings. The energy-saving potential of such a device is dependent on the parameters responsible for heat and moisture recovery. The trend is toward composite membranes, which are custom produced, and their parameters can be adjusted for a given application; therefore, the diffusion and sorption characteristics of such membranes are unknown. In order to obtain the values of the water vapor diffusivity of three investigated handmade membranes, a serial resistance model using a Field and Laboratory Emission Cell (FLEC) is proposed. Experiments were conducted to identify the resistance in each step of the moisture transfer process to extract the moisture diffusivity in the membranes. The calculated moisture diffusivities in the membranes were 8.99 × 10−12 (m2/s) for the membranes from cellulose acetate, 1.9 × 10−10 (m2/s) for the microporous PE/PUR membranes, and 1.53 × 10−11 (m2/s) for the PET/PUR microfibrous membranes. The obtained membrane diffusivities were then used in the proposed effectiveness-NTU-based model of an exchanger with a cross-flow arrangement to predict performance under various operating conditions. The results show that the highest latent effectiveness was found for the exchanger core made from the PE/PUR membrane and the lowest was for the one with the PE/PUR membrane core.

There is a clear relationship between indoor air quality, gaseous compounds (volatile and semi-volatile) and particles emitted by building materials, biogenic and anthropogenic activities, and human health. An increased interest in indoor air quality and emissions has raised during recent years. Nowadays, it is possible to find several analytical approaches based on a wide variety of sampling and analytical techniques. The main objective of this review is to clarify the different options available for the analyst by a critical evaluation of the different steps involved in these methods. In this way, a clear description and evaluation of the potential advantages and shortcomings for the different devices required in materials emission studies, the collection of total air samples using air canisters and particles by vacuum surface have been included in this review. In addition, the potential use of active and passive sampling techniques, for the efficient collection of different compounds from the air samples is described. Then, the selection of the most adequate analytical approach for the analysis of different compounds as a function of their physicochemical properties is evaluated. The latter will include not only traditional approaches such as gas or liquid chromatography but also more sophisticated ones such as proton transfer reaction or chemical ionization mass spectrometry. Finally, the application of these different analytical approaches to the evaluation of indoor air emissions, mainly from biogenic and anthropogenic activities but also from different building materials, are introduced.

The emissions of volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) from indoor building and vehicle cabin materials can adversely affect human health. Many mechanistic models to predict the VOC/SVOC emission characteristics have been proposed. Nowadays, the main obstacle to accurate model prediction is the availability and reliability of the physical parameters used in the model, such as the initial emittable concentration, the diffusion coefficient, the partition coefficient, and the gas-phase SVOC concentration adjacent to the material surface. The purpose of this work is to review the existing methods for measuring the key parameters of VOCs/SVOCs from materials in both indoor and vehicular environments. The pros and cons of these methods are analyzed, and the available datasets found in the literature are summarized. Some methods can determine one single key parameter, while other methods can determine two or three key parameters simultaneously. The impacts of multiple factors (temperature, relative humidity, loading ratio, and air change rate) on VOC/SVOC emission behaviors are discussed. The existing measurement methods span very large spatial and time scales: the spatial scale varies from micro to macro dimensions; and the time scale in chamber tests varies from several hours to one month for VOCs, and may even span years for SVOCs. Based on the key parameters, a pre-assessment approach for indoor and vehicular air quality is introduced in this review. The approach uses the key parameters for different material combinations to pre-assess the VOC/SVOC concentrations or human exposure levels during the design stage of buildings or vehicles, which can assist designers to select appropriate materials and achieve effective source control.

A suitably chosen reference material should meet specific criteria like representing one of the compound classes most commonly occurring in indoor materials as well as having optimal long-term stability during storage and transport to its destination point and having a compact size. The described interdisciplinary pilot research was aimed to develop and characterize a polymer-based candidate for the laboratory reference material (LRM) of selected representatives of monoaromatic hydrocarbons (toluene and furfural) and terpenes emissions. Recycled, petroleum-based low-density polyethylene (LDPE) was applied as a matrix and was filled with plant-based wastes, such as apple pomace (AP), sunflower husks (SH), or yerba mate (YM) residues. The performance and suitability of the developed candidate for use as laboratory reference material was analyzed using FT-IR spectroscopy and differential scanning calorimetry (DSC). The migration potential of the representatives of monoaromatic hydrocarbons and terpenes emitted from the developed polymer material was assessed using the stationary emission microchamber system (μ-CTE 250). In the case of candidates for LRM with the addition of YM and AP, a clear relationship was observed between the samples seasoning time in the chamber and the total amount of VOCs released into the gaseous phase, including identified and determined representatives of terpenes. Furthermore, the existence of a clear relationship between the size (intensity) of the emission defined by the calculated summary parameters (TVOCs and sum of terpenes) and the seasoning/conditioning temperature of polymeric materials with bioadditives was observed.

Background: TVOC (total volatile organic compounds) has been used as a sum parameter in indoor air sciences for over 40 years. In the beginning, individual VOC concentrations determined by gas chromatography were simply added together. However, several methods for calculating TVOC have become established over time. Methods: To understand the manifold definitions of TVOC, one must trace the history of indoor air sciences and analytical chemistry. Therefore, in this work, the original approaches of TVOC are searched and explained. A detailed description of the measurement methods is followed by a critical evaluation of the various TVOC values and their possible applications. The aim is to give the reader a deeper understanding of TVOC in order to use this parameter correctly and to be able to better assess published results. In addition, related sum values such as TSVOC and TVVOC are also addressed. Results: A milestone was the analytical definition of VOCs and TVOC in 1997. A list of VOCs that should at least be considered when calculating TVOC was also provided. This list represented the status at that time, is no longer up-to-date and is being updated by a European working group as part of a harmonization process. However, there is still confusion about the exact definition and reasonable application of TVOC. The signals of other sum parameters, measured with photoacoustics, flame ionization, photoionization or electrochemical sensors, are also often given under the term TVOC. Conclusions: It was recognized early that TVOC is not a toxicologically based parameter and is therefore only suitable for a limited number of screening purposes. Consequently, TVOC cannot be used in connection with health-related and odor-related issues. Nevertheless, such references are repeatedly made, which has led to controversial scientific discussions and even court decisions in Germany about the correct and improper use of TVOC.

One of the more important classes of potentially toxic indoor air chemicals are the Volatile Organic Compounds (VOCs). However, due to a limited understanding of the relationships between indoor concentrations of individual VOCs and health outcomes, there are currently no universal health-based guideline values for VOCs within Europe including the UK. In this study, a systematic search was conducted designed to capture evidence on concentrations, emissions from indoor sources, and health effects for VOCs measured in European residences. We identified 65 individual VOCs, and the most commonly measured were aromatic hydrocarbons (14 chemicals), alkane hydrocarbons (9), aldehydes (8), aliphatic hydrocarbons (5), terpenes (6), chlorinated hydrocarbons (4), glycol and glycol ethers (3) and esters (2). The pathway of interest was inhalation and 8 individual aromatic hydrocarbons, 7 alkanes and 6 aldehydes were associated with respiratory health effects. Members of the chlorinated hydrocarbon family were associated with cardiovascular neurological and carcinogenic health effects and some were irritants as were esters and terpenes. Eight individual aromatic hydrocarbons, 7 alkanes and 6 aldehydes identified in European residences were associated with respiratory health effects. Of the 65 individual VOCs, 52 were from sources associated with building and construction materials (e.g. brick, wood products, adhesives and materials for flooring installation etc.), 41 were linked with consumer products (passive, electric and combustible air fresheners, hair sprays, deodorants) and 9 VOCs were associated with space heating, which may reflect the relatively small number of studies discussing emissions from this category of sources. A clear decrease in concentrations of formaldehyde was observed over the last few years, whilst acetone was found to be one of the most abundant but underreported species. A new approach based on the operational indoor air quality surveillance will both reveal trends in known VOCs and identify new compounds.

Recently, research has established a screening system comprising a combination of two technologies, the MEMS sensor and the field and laboratory emission cell (FLEC), to perform experiments. The aim of our study was to establish MEMS sensor field emission cell technology (MS-FECT) to measure the changes in the pollutant concentration of field emission cells. A building material emission database was created via an Internet of Things (IoT) in order to develop a MEMS sensor field emission modeling platform. On the basis of information of the building material emission database and decay models, the MS-FECT, IoT, indoor positioning system (Beacon), and cloud database are integrated in this system. The source of pollution was determined by sensing and data analysis to create a multidimensional map of pollution sources to determine air quality in order to monitor the location of pollutants and flow conditions in the long term to change the indoor air quality efficiently. Moreover, the results of this study will be helpful in house interior design, the maintenance of residents' health, and the reduction of carcinogenic threats.

Beyond their indoor emission by various sources, another aspect of the presence of VOCs in confined environments involves their indoor fate. Terpenes, because of their ubiquity, source variety and reactivity, are VOCs whose contributions to the indoor air quality may largely exceed primary emissions because of possible secondary processes such uptake and secondary emissions. Limonene is flagged as a species typifying the behavior of terpenes, and a selection of representative indoor materials is proposed. Limonene uptake characterization of selected surfaces is performed under typical indoor conditions using a FLEC-based experimental setup allowing (i) limonene partitioning coefficient determination and (ii) quantification of the reversible nature of this interaction. Interestingly, the materials of interest exhibit highly differentiated affinities for limonene, evidencing the contrast in their surface contributions to terpene loss. Glazing is confirmed as a non-significant sink, while cotton fabric and gypsum board are major contributors to limonene surface loss and exhibit high surface uptake capacities. This work allows a quantitative ranking of the selected materials from minor to major limonene sinks. Reversibility quantification of the uptake process provides key insights into further secondary limonene emissions. The major sink materials are highlighted such as inducing irreversible limonene uptake, thus creating indoor surface pools of reactive organics possibly available for further oxidation processes.

Actual methods for on-site measurement of gaseous concentrations of Semi-Volatile Organic Compounds (SVOCs) at the material surface (y0) are not yet sufficiently developed mainly due to sampling difficulties. These concentrations are the key data to improve knowledge about indoor sources and human exposure to SVOCs. To the end, a specific emission cell coupled to solid-phase microextraction (SPME) was developed. The main challenge with this method is calibration because of very low volatility of SVOCs and static sampling mode. In this study, a generating system of organophosphate flame retardants (OFRs) using polyurethane foam as source combined with an active sampling method with Tenax tubes was proposed as a novel calibration device for SPME-based method. The generating system delivered stable OFR concentrations after 190 h of operation with a variation not exceeding ±5%. It allowed to obtain robust calibrations for tris-(2-chloropropyl)-phosphate (TCPP) and tri-butyl-phosphate (TBP) measured with the emission cell coupled to SPME-based method, define the optimal sampling requirements and achieve reproducible and accurate measurements of y0 at μg.m−3 level. TCPP and TBP gas-phase concentrations at the polyurethane foam surface (y0) were followed up over more 228 days under controlled temperature conditions. A high stability of these concentrations was observed showing that polyurethane foam acts as a stable and continuous source of organophosphate flame retardants indoors. This novel method should be useful for assessing the dynamic of emissions from indoor sources and potential exposure to SVOCs in indoor environments.

Degrading 2-ethylhexyl-containing PVC floorings (eg DEHP-PVC floorings) and adhesives emit 2-ethylhexanol (2-EH) in the indoor air. The danger of flooring degradation comes from exposing occupants to harmful phthalates plasticisers (eg DEHP), but not from 2-EH as such. Since the EU banned the use of phthalates in sensitive applications, the market is shifting to use DEHP-free and alternative types of plasticisers in PVC products. However, data on emissions from DEHP-free PVC floorings are scarce. This study aimed at assessing the surface and bulk emissions of two DEHP-free PVC floorings over three years. The floorings were glued on the screed layer of concrete casts at 75%, 85%, and 95% RH. The volatile organic compounds (VOCs) were actively sampled using FLEC (surface emissions) and micro-chamber/thermal extractor (µ-CTE, bulk emissions) onto Tenax TA adsorbents and analyzed with TD-GC-MS. 2-EH, C9-alcohols, and total volatile organic compound (TVOC) emissions are reported. Emissions at 75% and 85% RH were similar. As expected, the highest emissions occurred at 95% RH. 2-EH emissions originated from the adhesive. Because the two DEHP-free floorings tested emitted C9-alcohols at all tested RH, it makes the detection of flooring degradation harder, particularly if the adhesive used does not emit 2-EH.

Semi-volatile organic compounds (SVOCs) in indoor environments can partition among the gas phase, airborne particles, settled dust, and available surfaces. The mass transfer parameters of SVOCs, such as the mass transfer coefficient and the partition coefficient, are influenced by indoor environmental factors. Subsequently, indoor SVOC concentrations and thus occupant exposure can vary depending on environmental factors. In this review, the influence of six environmental factors, i.e., indoor temperature, humidity, ventilation, airborne particle concentration, source loading factor, and reactive chemistry, on the mass transfer parameters and indoor concentrations of SVOCs was analyzed and tentatively quantified. The results show that all mass transfer parameters vary depending on environmental factors. These variations are mostly characterized by empirical equations, particularly for humidity. Theoretical calculations of these parameters based on mass transfer mechanisms are available only for the emission of SVOCs from source surfaces when airborne particles are not present. All mass transfer parameters depend on the temperature. Humidity influences the partition of SVOCs among different phases and is associated with phthalate hydrolysis. Ventilation has a combined effect with the airborne particle concentration on SVOC emission and their mass transfer among different phases. Indoor chemical reactions can produce or eliminate SVOCs slowly. To better model the dynamic SVOC concentration indoors, the present review suggests studying the combined effect of environmental factors in real indoor environments. Moreover, interactions between indoor environmental factors and human activities and their influence on SVOC mass transfer processes should be considered.

Phthalates are ubiquitously present environmental contaminants. Air and dust are the most important mediums of exposure to phthalates. The present study reviews the presence of phthalates in the air and dust reported from different countries in the last ten years (2007–2017). The phthalate concentrations revealed wide heterogeneity with a mean and median value 6 ± 19 μg/m3 and 0.5 μg/m3 respectively in the air and 1.5 × 103 ± 2.2 × 103 μg/g and 7.8x102μg/g respectively in the dust. The highest phthalates levels in the air were reported from India (1.1 × 102 μg/m3) and in dust from Bulgaria (1.2 × 104 μg/g). Overall higher levels were reported from developing countries as compared to developed countries. Di (2-ethylhexyl) phthalate (DEHP) and Di-n-butyl phthalate (DBP) were found to be predominant in both air and dust. Temperature, humidity, air exchange rate, building material and indoor maintenance were reported as the important factors influencing the levels of phthalates in the air and dust. In addition to policy level interventions, reducing the use of phthalate containing materials and controlling the factors which enhance the emission from existing sources can help in reducing human exposure to phthalates.

Indoor air pollution requires the development of various approaches to reduce the concentration of VOCs. Beyond the optimization of ventilation and the reduction of pollutant sources, building materials with sorptive properties are currently examined as possible VOC remediation processes. The potentialities and the effectiveness of sorptive building materials still require detailed and reliable assessments. Thus, the objective of this paper relies in the development of a methodology to determine VOC partitioning coefficients on two sorptive building materials, in comparison with a non-sorptive one, using two contrasted model VOCs, namely toluene and formaldehyde, under different environmental indoor conditions. This approach aims at comparing the different materials and estimating their lifetimes regarding VOC uptake under realistic indoor conditions. After exposing the experimental methodology, uptakes of toluene and formaldehyde are investigated on the three selected gypsum boards. The determination of respective partitioning coefficients enlightens the contrasted behaviours of boards depending on (i) the presence or absence of sorptive agent in their formulation, (ii) the nature of the sorptive agent used, (iii) the structure of the model VOC, (iv) the paper layer on board and (v) the relative humidity. Based on obtained experimental results, the lifetimes of boards are evaluated for each VOC. Results evidence that improvements still have to be achieved to enhance the significance of sorptive gypsum board on indoor air quality. Nevertheless, reliable methodologies are now available to assess the behavior of these materials in indoor environment and to help their effective optimization.

Formaldehyde has been discussed as a typical indoor pollutant for decades. To evaluate the current state-of-the-art in formaldehyde research and to identify the plethora of regulated and unregulated formaldehyde sources in indoor and outdoor spaces, an extensive literature search was carried out. The acquired data were analyzed with the aid of Monte-Carlo methods to calculate realistic formaldehyde concentration profiles and exposure scenarios under consideration of aging, source/sink behavior and diffusion effects. Average concentrations of formaldehyde are within 20–30 µg/m³ for European households under residential-typical conditions. The assumption of an average air exchange rate of 0.5 h−1 is also plausible. Formaldehyde emission rates of materials and products for indoor use are widely spread and range from non-detectable to > 1000 µg/h. However, processes like combustion, cleaning activities, operation of air purifiers and indoor chemistry were identified as temporary but relevant formaldehyde sources, which might cause high peak concentrations.

The assessment of VOC emission rates and sorption coefficients was performed for ten surfaces present within a classroom, using field and laboratory emission cells (FLEC) coupled to online and off-line VOC quantification techniques. A total of 21 identified VOCs were emitted by the different surfaces. VOC emission rates measured using PTR-ToF-MS were compared to gas chromatographic measurements. The results showed that the two methods are complementary to one another. Sorption parameters were also successfully measured for a mixture of 14 VOCs within a few hours (<17 hours per surface). A study of the spatial and temporal variability of the measured parameters was also carried out on the two surfaces that presented the most potential for interaction with VOCs, accounting for the largest surface areas within the room. The dataset of emission rates and sorption parameters was used in the INCA-Indoor model to predict indoor air concentrations of VOCs that are compared to experimental values measured in the room. Modeling results showed that sorption processes had a limited effect on indoor concentrations of VOCs for these field campaigns. Modeled daily profiles show good agreement with the experimental observations for VOCs such as toluene (indoor source) and xylenes (outdoor source) but underestimate concentrations of methanol (both indoor and outdoor sources).

This paper presents an adsorption boundary condition based on linear adsorption isotherm for Lattice Boltzmann (LB) model. An axisymmetric 2-D LB model is built for an axisymmetric device. The model is used to study the effects of surface adsorption and airflow on SVOC mass transport in the device. In terms of surface adsorption, the research is divided in two parts: pure diffusion and convection-diffusion. The results show that the simulated data based on the presented adsorption boundary agree well with experimental data. In both the pure diffusion and advection-diffusion process, surface adsorption has no impact on the steady-state concentration, but it affects the time to reach steady state. Airflow greatly reduces both the time to reach steady state and the steady-state concentration. An exponential relationship involving hm, ACH and velocity is proposed and verified experimentally. Discussion on the parameter n in the exponential relation is conducted.

Semi-volatile organic compounds (SVOCs) are widely used in various indoor materials and their adverse health effects have been increasingly recognized. The gas-phase SVOC concentration in equilibrium with the source material (y0), as a characteristic parameter for SVOC sources, is mostly assumed to be constant in previous studies. However, decreases in y0 with time have been observed in some studies. As a first step to reveal the mechanism behind the phenomenon, this study quantitatively investigated the variation of y0 over time under two conditions: natural exposure to outdoor ambient (Case 1), and storage in a controlled ventilated chamber (Case 2). Three phthalates (Di-iso-butyl Phthalate (DiBP), Di-n-butyl Phthalate (DnBP), and di-(2-ethylhexyl) phthalate (DEHP)) emitted from polyvinyl chloride (PVC) floorings and one flame retardant (tris(2-chloroisopropyl) phosphate, TCPP) emitted from polyurethane foam (PUF) were targeted. Experimental results indicated that, for SVOCs with higher volatility, i.e., DiBP, DnBP, and TCPP, y0 decreased 16%–49% after 60 days' exposure for Case 1; and 16%–36% for Case 2. For SVOCs with lower volatility, i.e., DEHP, no significant decrease in y0 was observed after 60 days in both cases; while if prolonging the time to about 1.5 years, a decrease of 38% was observed. Discussion about potential reasons for the decrease of y0 was presented. The results obtained here provide a further understanding about SVOC source characteristics and therefore help providing source strength for estimating indoor SVOC health exposure.

For several years intensive research has been carried out with the aim of developing a database of the types and amounts of pollutants released from indoor materials to the indoor environment. The paper discusses in detail basic problems and challenges encountered when estimating the emissions of chemical compounds released from of indoor materials. Factors affecting the validity of data obtained by using two different types of analytical devices operating in a dynamic mode (the ex-situ methods) or passive mode (the in-situ methods) for collecting the analytes samples from the gaseous phase were discussed. The main advantages and important limitations of specific analytical devices and aspects of the morphology of the studied indoor material that may influence the type and amount of chemical compounds released into the air were also highlighted. Attention has also been drawn to challenges encountered when developing candidate reference materials dedicated for measuring emissions from indoor matrices.

The present study introduces an air treatment system (ATS) for improving indoor air quality and reducing the energy consumption of air-conditioning system. The ATS has been proposed to combine three sub-systems, namely, (i) energy-efficient oxygen production sub-system, (ii) ozone-based oxidation treatment sub-system, and (iii) air scrubbing sub-system. Experimental setups have been designed and constructed to study the performance of primary equipment in the ATS. The proposed air-purification process is able to reduce the concentration of indoor air pollutants such as volatile organic compound. The experimental results have demonstrated that the proposed ATS enables a lower outdoor air intake rate resulting in a reduced cooling load. Considering the energy consumption of primary equipment of the ATS operating in tropical climates, the total energy consumption can be reduced from 52.18 W/m2 to 41.26W/m2 by regulating the outdoor air intake rate from 10 L/s per person to 4 L/s per person.

This study has investigated the total inflammatory potential (TIP) of low concentration fungal samples from moisture-damaged and fungal infested gypsum boards. The fungal aerosols were generated from damp and dried surfaces, and sampled using filter sampling and liquid impingement. The TIP of the samples was analysed using a granulocyte assay based on differentiated HL60 cells. The study found a tendency to a J-shaped dose-response curve for fungal samples. Low concentrations of fungi were aerosolised from the gypsum boards, and the aerosols were dominated by Aspergillus versicolor and Penicillium chrysogenum. Bacillus infantis and Paenibacillus sp. were found on the gypsum boards, but not recovered in the aerosols. A significant correlation was found between the TIP of diluted and undiluted samples of fungal aerosols. However, diluted samples had a higher TIP than undiluted samples, and no significant association was found between concentration of fungi and the TIP of the samples. This is likely due to the J-shaped dose response curve. The aerosol samples from the dried gypsum boards had a significantly higher TIP compared to aerosols from the damp surfaces. However, the J-shaped dose-response curve weakens the conclusion on the influence of surfaces dampness, sampling time, fungal species or sampling methods. It could, however, be concluded that samples from both damp and dry surfaces induce inflammation in the HL60 cells, despite the low concentration of fungi. Thus, a dried fungal infestation in a building seem still to present a concern for the occupant.

Several studies have shown an association between dampness and health issues like headache and asthma. To better understand the exposure risk of fungal growth in buildings this study investigates the release of fungi from gypsum boards infested with fungi from a moisture-damaged house. Further, the composition and concentration of fungal species in indoor air of five non-moisture-damaged homes are analysed, and the ratio between species associated- and not associated with moisture-damaged buildings are related to air change rate (ACR) and relative humidity (RH). The air velocity near the surface of the gypsum boards in combination with the changes in sampling time influenced the particle release rate. After 8 h particles were still released, and more species were released during 8 h with low air velocity than during 15 min with high air velocity. More fungal species and a higher release rate were found from damp surfaces with substantial growth than from gypsum boards dried out before they were totally colonized. In the five homes ACR and RH had a significant influence on the fungal species composition. Thus, a low ACR and a high RH were associated with increased ratio of species associated with moisture-damage relative to species not associated with moisture-damage. In conclusion, increasing the ventilation and reducing the RH of the indoor air will have a beneficial effect on the airborne species composition. Further, fast action by drying out a fungal infestation has a positive impact on the exposure risk in terms of exposure level and species composition.

The design of air conditioning mechanical ventilation (ACMV) system affects the building energy performance and the indoor pollutant removal process. The present study aims to reduce energy consumption on ACMV systems by employing a renewable air treatment system (ATS). The ATS is able to purify the recirculated air through the ozone-based oxidation process and air scrubbing devices. The air purification performance of primary equipment in the ATS has been studied in order to demonstrate the capability to remove indoor air pollutants. Due to the air purification process, the ATS allows a reduced supply of outdoor-air translating to a lower cooling load. In addition, the reduced outdoor-air fraction results in an improved chiller efficiency. Therefore, the ATS is capable of achieving marked energy savings because of the reduced cooling load for conditioning outdoor airflow. The proposed ATS is particular adept during a period when Singapore faces periodic bad haze situations. Activating the ATS while decreasing the outdoor-air fraction can be an attractive solution. Based on Singapore climatic condition, an energy consumption analysis has been carried out to estimate the energy saving potential of the proposed ATS with varying outdoor-air intake. The “plug-and-play” ATS can be easily integrated into any new or existing ACMV systems to realize immediate improvement in indoor air quality and building energy efficiency.

The chapter deals with different aspects on the use and performance of bio-based building materials in constructions and buildings.

A new method was developed to measure on the field VOC sorption coefficients (ka; kd) on the surface of a material by coupling a Field and Laboratory Emission Cell (FLEC) to a Proton Transfer Reaction-Mass Spectrometer (PTR-MS) as presented in the first part of this study. In this second part, the method is compared to the classical method based on a CLIMPAQ chamber coupled to an on-line GC analyzer. Different models were used to determine the sorption parameters from experimental data taking into account the sink effect on empty chamber walls and the presence of a boundary-layer. Determined sorption equilibrium coefficients Ke (ka/kd) for a mixture of BTEX on a gypsum board was found to be in good agreement between both methods. However, the CLIMPAQ method seems to be less robust than the FLEC method in the determination of sorption coefficients since more than one couple of (ka; kd), showing the same ratio Ke can retrieve the same CLIMPAQ experimental data. Giving this result, the question arises about the reliability of the literature data determined using emission test chamber which could be one of the reasons behind the discrepancies found between experimental indoor concentrations and predicted ones using chamber derived parameters.

Semi-volatile organic compound (SVOC) in indoor environment is an important research topic because of their wide use and persistent effect on human health. SVOC chambers have been continually improved to study the mass transfer characteristics in indoor environment. CFD method is used in the present paper to study the effect on mass transfer, especially on steady time by velocity field from the comparison of SVOC mass transfer in two different SVOC chambers (A and B). The results indicate that the variance of air flow in small range strongly affects the steady concentration and has no obvious effect on steady time. Sorption ability itself has great impact on steady time. The great reduction of steady time in Chamber B is the combined effect of sorption and velocity field. The velocity field resulted from the special structure of Chamber B leads to a stronger convective mass transfer resistance, and hence causes a weaker effective sorption. Therefore, the less steady time in Chamber B is the result of weaker effective sorption besides a less sorption area of Chamber B than Chamber A.

Semi-volatile organic compounds (SVOCs) are indoor air pollutants that may have significant adverse effects on human health. Although emissions of volatile chemicals from building materials and consumer products are usually characterized in small chambers, few chamber studies have been conducted for SVOCs due to the challenges associated with analysis and the lack of validation procedures. There is an urgent need for a reliable and accurate chamber test method to verify these measurements. A reference method employing a specially-designed chamber has been developed and is undergoing extensive evaluation. A pilot inter-laboratory study (ILS) has been conducted with six laboratories performing chamber tests under identical conditions for di-2-ethylhexyl phthalate (DEHP). Results from this study showed inter-laboratory variations of 24% for DEHP emission rates, with closer agreement observed among intra-laboratory measurements for most of the participating laboratories. A mechanistic emission model fits well to the measured concentration profiles, demonstrating the feasibility of the proposed reference method to independently assess laboratory performance and validate SVOC emission tests.

Over the last 30years, several experimental chambers were developed and implemented for indoor air studies. Yet, they were not all representative of real indoor air conditions. Either they did not have sufficient volumes or they were hindered by difficulties to control experimental conditions and air exchange rates. In this context, a 40m3 Innovative experimental Room for Indoor Air studies (IRINA) has been developed and validated at Mines Douai (Atmospheric Sciences et Environmental Engineering department (SAGE)) to overcome these drawbacks and above all to perform reproducible indoor air studies avoiding any possible experimental biases. IRINA inner walls are covered with aluminum foils. The room is operated in a closed mode and is equipped with a VOC injection system that relies on the heated and pressurized injection of vaporized VOC. IRINA is also equipped with analytical instruments that allow the analysis of both gas (online and offline measurements) and particle phases. IRINA validation evidenced that: (i) the air exchange rate of the room is well controlled over an one year timespan; (ii) both gaseous and particulate background levels in IRINA remain lower than typical indoor air conditions; (iii) fast homogenization of injected VOC concentrations is reached in the room; (iv) adsorption phenomena on IRINA walls are limited; and (v) there is no VOC matrix impact regarding individual VOC decays. The modelling of VOC natural decay in IRINA based on the new INCA-Indoor model showed that the VOC removal in IRINA is mainly due to the air exchange rate.

Polychlorinated biphenyls (PCBs) were used in building materials like caulks and paints from 1930–1970s and in some cases that caused elevated PCB concentrations in the indoor air at levels considered harmful to occupant health. PCBs are semivolatile organic compounds and capable of spreading from the original source to adjacent materials, indoor air and via adsorption from the air to indoor surfaces, causing secondary contaminations. Remediation of buildings with unsatisfactory indoor air concentrations is a complex and difficult task due to the secondary contamination of building materials and there is a need to prioritise remediation measures on different materials. An inexpensive and portable emission test cell was developed to resemble indoor conditions in relation to the area specific ventilation rate. Emissions were measured using the test cell in the laboratory on freshly made PCB paint. Further, the chamber was used for determining emissions from PCB-containing building materials in the field as well as remediated walls. The measurements showed that sorption of PCBs to chamber walls was insignificant after 2–4 days of exposure to the source. Over a period of two weeks emission rates did not change from any of the tested surfaces, however in the laboratory experiment emission rates decreased over a longer period (48 days) and was most pronounced for the lower chlorinated PCBs.

Several physicochemical processes occurring within buildings are key drivers of indoor concentrations of Volatile Organic Compounds VOCs. Many models and experimental studies have been proposed to predict VOCs concentration indoors given these processes. However, there is a lack of representative data in literature to present gas–surface interaction in order to validate mathematical models. This work is divided in two parts and aims to develop and validate a method to perform fast measurements of VOC sorption parameters on the field by coupling a Field and Laboratory Emission Cell (FLEC) to a Proton Transfer Reaction-Mass Spectrometer (PTR-MS). In the part 1 of the work, sorption coefficients of aromatic compounds on a gypsum board and vinyl flooring were investigated at ppb levels to test and evaluate the proposed methodology. Sorption coefficients in the range of 0.03–1.88 m h−1 for ka and 2.04–17.32 h−1 for kd were successfully measured within a (0.5–8 h) for the two materials. Robustness tests highlight that the determination of sorption coefficients does not depend on operating conditions. While sorption coefficients for the gypsum board were measured with a PTR-MS time resolution of 20 s, the vinyl flooring material required measurements at a higher time resolution of 2 s due to its lower sorption properties. Limits of applicability assessed for this method indicate that sets of sorption parameters (ka, kd) of (0.01 m h−1; 0.01 h−1) and (0.09 m h−1; 0.09 h−1) can be measured with an accuracy better than 10% at time resolutions of 2 and 20 s respectively.

Phthalates are important endocrine disrupting chemicals that have been linked to various adverse human health effects. Phthalates are ubiquitously present in indoor environment and could enter humans. Vinyl or PVC floorings have been recognized as one of important sources of phthalate release to indoor environment including house dust. In the present study, we estimated the migration of di(2-ethylhexyl)phthalate (DEHP) and di-isononyl phthalate (DINP) from the flooring materials into the dust under different heating conditions. For this purpose, a small chamber specifically designed for the present study and a Field and Laboratory Emission Cell (FLEC) were used, and four major types of PVC flooring samples including two UV curing paint coated, an uncoated residential, and a wax-coated commercial type were tested. Migration of DEHP was observed for an uncoated residential type and a wax-coated commercial type flooring. After 14days of incubation, the levels of DEHP in the dust sample was determined at room temperature on average (standard deviation) at 384±19 and 481±53μg/g, respectively. In contrast, migration of DINP was not observed. The migration of DEHP was strongly influenced by surface characteristics such as UV curing coating. In the residential flooring coated with UV curing paint, migration of DEHP was not observed at room temperature. But under the heated condition, the release of DEHP was observed in the dust in the FLEC. Migration of DEHP from flooring materials increased when the flooring was heated (50°C). In Korea, heated flooring system, or ‘ondol’, is very common mode of heating in residential setting, therefore the contribution of PVC flooring to the total indoor DEHP exposure among general population is expected to be greater especially during winter season when the floor is heated.

The accurate and rapid determination of the emission parameters of semi-volatile organic compounds (SVOCs) from indoor materials is of great importance for estimating and controlling indoor exposure. By virtue of a simplified mass transfer model we derived, a new method called the early stage C-history method, has been developed to measure the key emission parameters: the gas phase SVOC concentration adjacent to the material surface (y0) and the convective mass transfer coefficient (hm). We validate this model using experimental data found in the literature. When compared with established methods, the new method has the following salient features: (1) rapid (the experimental time is reduced from several months to several days); (2) accurate (R2 in the range of 0.92–0.97). Further analysis shows that both features can be further improved if the test system has a smaller chamber wall/air partition coefficient. The new method is also extended to measure the key parameters of SVOCs from sorption materials. This method should prove useful for screening SVOC emission characteristics and for assessing exposure, as well as for chamber and test design.

Emission rates of bis(2-ethylhexyl)phthalate (DEHP) from poly(vinyl chloride) (PVC) sheets containing DEHP as a plasticizer at various contents (0.16%–32.3%) were measured using the passive gas flux sampling method. The gas sampler was made of Pyrex glass and had a glass fiber filter inside. The sampler was placed on the surface of a PVC sheet for a given sampling period (up to 24 h), then the DEHP captured by the glass fiber filter was determined by gas chromatography-mass spectrometry. The sampling temperature was 50 °C. The surface concentration y0 (the DEHP concentration in the gas immediately adjacent to the surface of the PVC sheet) was determined from the experimental results and a transient DEHP emission model. The surface concentrations that were found agreed with values that have previously been published, most of which were determined in chamber emission experiments that require a longer test period than was used here. The method presented therefore allows the surface concentration y0, which is considered to be one of the most important parameters determining SVOC emissions from solids such as PVC sheets, to be determined quickly and simply. The experimentally determined surface concentrations and the DEHP contents of the PVC sheets that were used correlated well.

The di-(2-ethylhexyl) phthalate (DEHP) concentration in the air immediately adjacent to a polyvinyl chloride (PVC) flooring surface, y0 (μg/m3), has been identified as one of the critical parameters governing the emission process and consequent exposure. At room temperature and below, the relationship between y0 and the vapor pressure of pure DEHP (Psat) is still unclear. Few studies have been conducted to examine the influence of the mass fraction of DEHP in PVC on the relationship. In this study a new closed-chamber solid phase microextraction (SPME) method is developed to characterize ratio of y0 to Psat at 23 °C. This method avoids the artifact from wall-loss of sampling lines and of the thermal desorption system, in contrast to ventilated-chamber methods. Results show that at 23 °C y0 is significantly lower than the vapor pressure of pure DEHP. When the mass fraction of DEHP in PVC flooring increases from 13% to 23%, y0/Psat is increased by 7.2%, similar to what is reported in the literature. The sorption capacity of SPME stainless steel (SS) rods differs by up to 104%, although they are all made of SS. Based on error analysis, strategies are recommended to improve the precision and time efficiency. The method developed here should work for other SVOC-polymer systems.

Two primary schools and one kindergarten were selected in the city of Kozani, Greece in order to investigate the school environment, the indoor air pollutants that children are exposed to and possible health risks at school. In each school three classrooms and one outdoor position were monitored from Monday to Friday, in both non-heating (26/09/2011–14/10/2011) and heating (23/01/2012–10/02/2012) period. Temperature, relative humidity and CO2, were continuously monitored. Formaldehyde, benzene, trichloroethylene, pinene, limonene, NO2 and O3 were measured with diffusive samplers. CO was monitored every day (30 min/day). Radon was measured for four weeks with short term radon detectors. PM2.5 was gravimetrically determined while PM2.5 and PM10 fractions were measured using the optical light scattering technique. Building material emission testing for VOCs was performed using the Field and Laboratory Emission Cell (FLEC). The ventilation rate for each classroom was calculated based on the CO2 measurements. Results indicated that indoor air concentrations of the measured pollutants were within accepted limits with indicative ranges 1.5–9.4 μg/m3 for benzene, 2.3–28.5 μg/m3 for formaldehyde, 4.6–43 μg/m3 for NO2 and 0.1–15.6 μg/m3 for O3. Emissions from building materials seem to have a significant contribution to the indoor air quality. Very low ventilation rates (0.1–3.7 L/s per person) were observed, indicating inadequate ventilation and possible indoor air quality problems requiring intervention measures. The estimated average lifetime cancer risks for benzene, formaldehyde and trichloroethylene were very low.

The influence of the presence of the so-called seed particles on the emission rate of Tris (1-chloroisopropyl) phosphate (TCIPP) from polyisocyanurate (PIR) insulation boards was investigated in this study. Two Field and Laboratory Emission Test cells (FLEC) were placed on the surface of the same PIR board and respectively supplied with clean air (reference FLEC) and air containing laboratory-generated soot particles (test FLEC). The behavior of the area-specific emission rates (SERA) over a time period of 10 days was studied by measuring the total (gas + particles) concentrations of TCIPP at the exhaust of each FLEC. The estimated SERA of TCIPP from the PIR board at the quasi-static equilibrium were found to be 0.82 μg m−2 h−1 in the absence of seed particles, while the addition of soot particles led to SERA of 2.16 μg m−2 h−1. This indicates an increase of the SERA of TCIPP from the PIR board with a factor of 3 in the presence of soot particles. The TCIPP partition coefficient to soot particles at the quasi-static equilibrium was 0.022 ± 0.012 m3 μg−1. In the next step, the influence of real-life particles on TCIPP emission rates was investigated by supplying the test FLEC with air from a professional kitchen where mainly frying and baking activities took place. Similar to the reference FLEC outcomes, SERA was also found to increase in this real-life experiment over a time period of 20 days by a factor 3 in the presence of particles generated during cooking activities. The median value of estimated particle–gas coefficient for this test was 0.062 ± 0.037 m3 μg−1.

A test emission chamber called CLIMPAQ has been coupled to a chromatography analyzer GC to measure volatile organic compounds (VOC) concentration during a sorption experiments (Fast sorption measurements of VOCs on building materials: Part 2 - Comparison between FLEC and CLIMPAQ methods, (Rizk et al., In press) [1]). The equations used to calculate the mass transfer coefficient and the thickness of the boundary layer developed on the surface of a material are presented. In addition, the experimental profiles obtained using the CLIMPAQ chamber is also presented in the presence and the absence of a building material. Finally, the impact of chamber size on the obtained concentration profile using different chambers is shown using 3 types of chambers having different volumes, 1 m3, 30 m3 and a micro chamber of 40 mL.

Better understanding the transport mechanisms of organophosphorus flame-retardants (OPFRs) in the residential environment is important to more accurately estimate their indoor exposure and develop risk management strategies that protect human health. This study describes an improved dual small chamber testing method to characterize the sorption of OPFRs on indoor building materials and consumer products. The OPFRs studied were tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCIPP), and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP). The test materials and products used as sinks include concrete, ceiling tile, vinyl flooring, carpet, latex painted gypsum wallboard, open cell polyurethane foam, mattress pad and liner, polyester clothing, cotton clothing, and uniform shirt. During the tests, the amount of OPFRs absorbed by the materials at different exposure times was determined simultaneously. OPFRs air concentrations at the inlet and inside the test chamber were monitored. The data were used to rank the sorption strength of the OPFRs on different materials. In general, building materials exhibited relatively stronger sorption strength than clothing textiles. The material-air partition and material phase diffusion coefficients were estimated by fitting a sink model to the sorption concentration data for twelve materials with three OPFRs. They are in the range of 2.72 × 105 to 3.99 × 108 (dimensionless) for the material-air partition coefficients and 1.13 × 10−14 to 5.83 × 10−9 (m2/h) for the material phase diffusion coefficients.

Dust is an important sink for indoor air pollutants, such as polychlorinated biphenyls (PCBs) that were used in building materials and products. In this study, two types of dust, house dust and Arizona Test Dust, were tested in a 30-m3 stainless steel chamber with two types of panels. The PCB-containing panels were aluminum sheets coated with a PCB-spiked primer or caulk. The PCB-free panels were coated with the same materials but without PCBs. The dust evenly spread on each panel was collected at different times to determine its PCB content. The data from the PCB panels were used to evaluate the PCB migration from the source to the dust through direct contact, and the data from the PCB-free panels were used to evaluate the sorption of PCBs through the dust/air partition. Settled dust can adsorb PCBs from air. The sorption concentration was dependent on the congener concentration in the air and favored less volatile congeners. When the house dust was in direct contact with the PCB-containing panel, PCBs migrated into the dust at a much faster rate than the PCB transfer rate due to the dust/air partition. The dust/source partition was not significantly affected by the congener's volatility. For a given congener, the ratio between its concentration in the dust and in the source was used to estimate the dust/source partition coefficient. The estimated values ranged from 0.04 to 0.16. These values are indicative of the sink strength of the tested house dust being in the middle or lower-middle range.

Membrane-based total heat exchanger is a device to recover both sensible heat and moisture from exhaust air stream from a building. Heat and mass transfer intensification has been undertaken by using a structure of cross-corrugated triangular ducts. To further intensify moisture transfer, recently developed membranes-one step made asymmetric membranes, are used as the exchanger materials. Conjugate heat and mass transfer under transitional flow regime in this total heat exchanger are investigated. Contrary to the traditional methods of assuming a uniform temperature (concentration) or a uniform heat flux (mass flux) boundary condition, in this study, the real boundary conditions on the exchanger surfaces are obtained by the numerical solution of the coupled equations that govern the transfer of momentum, energy and moisture in the two air streams and in the membrane materials. The naturally formed heat and mass boundary conditions are then used to calculate the local and mean Nusselt and Sherwood numbers along the exchanger ducts, in the heat and mass developing regions. The data are compared with those results under uniform temperature (concentration) and uniform heat flux (mass flux) boundary conditions, for cross-corrugated triangular ducts with typical duct apex angles of 60° and 90°.

This study investigated phthalate emissions from vinyl flooring in a large-scale chamber. Vinyl flooring materials were examined for their phthalates content; one with high contents of diisononyl phthalate (DINP) and di(2-ethylhexyl) phthalate (DEHP) was selected for emissions testing in a small chamber at two different temperatures. Using the same type of vinyl flooring, large-scale chamber experiments were then conducted in three testing phases. In the first phase, the gas-phase concentrations of DINP and DEHP in the large chamber at 36 °C were about three times lower than those in the small chamber under the same temperature, which is consistent with its lower area/volume ratio. In the second phase, when a large air mixing fan inside the chamber was replaced with a small fan, the gas-phase concentrations of DINP and DEHP in the large chamber were reduced slightly, due to the decease of mass transfer coefficient and emission rate. During the last phase, when the temperature of the chamber was reduced to 25 °C, phthalate concentrations dropped instantly and steeply due to the significantly reduced emissions. However, they did not decrease as quickly thereafter because of desorption of phthalates from the internal surfaces of the large chamber. A fundamental mechanistic model was developed to interpret the experimental results in the large chamber based on the emission characteristics obtained in the small chamber measurements. Reasonable agreement was obtained between the model calculation and experimental data. Further model simulations show that temperature and air mixing above the source material have important effects on the fate of phthalates, while the impact of air change rate (ACH) is not significant.

This study investigated the influences of surface sorption and air flow rate on the emission of phthalates from building materials. Controlled tests were conducted in specially designed stainless steel and wood chambers, and the steady-state concentration in the stainless steel chamber was about 2–3 times higher than that in the wood chamber for di(2-ethylhexyl) phthalate (DEHP) and diisononyl phthalate (DINP). The emission rate of phthalates increased in the wood chamber due to the diffusion mass flow through the chamber wall (i.e., surface absorption). The adsorption isotherm of phthalates on the stainless steel surface and the absorption parameters (i.e., diffusion and partition coefficients) of phthalates on the wood surface were determined experimentally, and the values were comparable to those in the literature. The equilibration time scale for phthalates absorbed to the sink reservoir in actual indoor environments was estimated and can be substantial (approximately 80 years), indicating that surface absorption may continuously drive phthalates from their indoor sources to various sinks and thus significantly increase the emission rate of phthalates. The gas-phase concentration of DEHP was measured in two stainless steel chambers operated at flow rates of 300 mL/min and 3000 mL/min, respectively, which were both adjusted to 1000 mL/min after steady state was reached. The gas-phase concentration of DEHP in the chamber was very sensitive to the chamber air flow rate, and higher air flow rates resulted in lower concentration levels. However, the increased emission rate compensated for the dilution in the gas phase and made the DEHP concentration not drop substantially with an increase in the air flow rate. Independently measured or calculated parameters were used to validate a semi-volatile organic compounds (SVOCs) emission model that included absorptive surfaces and for a range of air flow rates, with excellent agreement between the model predictions and the observed chamber concentrations of phthalates.

Passive samplers have recently been proposed as simple and inexpensive tools to measure emissions of Volatile Organic Compounds (VOCs) from building and furnishing materials. These samplers can be used to pinpoint strong emitters of targeted pollutants, including hydrocarbons and oxygenated VOCs, which is of great interest to design efficient strategies aimed at improving indoor air quality. A passive sampler consists of a small cell that is exposed on a flat surface to trap material emissions. Three Passive Flux Samplers (PFS) have been developed at Mines Douai, an engineering school from Northern France, to carry out source apportionment studies of formaldehyde, acetaldehyde, and aromatic hydrocarbons, including benzene, toluene, xylenes, and higher molecular weight compounds. Over a 6-h exposure duration, these PFS exhibit linear responses and detection limits of a few μg m−2 h−1 that are low enough for monitoring material emissions and to perform extensive source apportionment studies. A few other samplers, designed using different geometries, have also been proposed in the literature. This publication summarizes findings on the development and the use of passive samplers with the objective to highlight the potential of these new tools for indoor air quality studies.

This paper presents a preliminary work to evaluate the steady state diffusion of volatile organic compounds (VOCs) in unsaturated building materials based on a newly-proposed fractal diffusion model. This model studies the contributions of water and gas to the diffusion transportation in unsaturated building materials, involves geometry parameters of unsaturated building materials, fractal dimensions, minimal and maximal pore diameters. In this model, the derivation of some parameters is assisted by newly-established three phases fractal carpet consisting of middle and peripheral parts that represent gas and water occupied regions in the unsaturated building materials. The influences of some structural parameters (removed number, recursion number and size) of fractal carpet on diffusion performance have been discussed. Additionally, the effective diffusion coefficients of various kinds of volatile organic compounds (formaldehyde, methanol, 1,3,5-trimethylbenzene, Ethylbenzene, xylene isomers, benzene and toluene) are also compared based on this fractal model. Formaldehyde exhibits the largest value of effective diffusion coefficient among selected VOCs.

A new method has been developed to measure sorption parameters on indoor surfaces on the field, based on the coupling of a Field and Laboratory Emission Cell (FLEC) and a Proton Transfer Reaction - Mass Spectrometer (PTR-MS). In this work, the method used for field applications is compared to the conventional method (used for laboratory scale experiment only) based on a 50-liter glass chamber (CLIMPAQ) coupled to an on-line GC analyser. The sorption of ethyl benzene on an unpainted gypsum board (exposed to a BTEX mixture) is presented. The CLIMPAQ experiment takes 13 times (160 hours) more than a FLEC experiment (12 hours). In addition, the FLEC walls do not present any sorption effect on internal walls while the CLIMPAQ shows important sink effect that can reach 45 ± 2% of the total amount of injected concentration. The sorption parameters ka and kd were derived from the experimental concentration profiles using Tichenor’s model and taking into account the walls sink effect for the CLIMPAQ. While the analysis of the FLEC data is very responsive to sorption parameters variation, the CLIMPAQ one leads to a large range of solutions for the same experimental profile. Therefore, the FLEC method is useful to measure ccurately and within few hours sorption parameters in real indoor environments.

Semi-volatile organic compounds (SVOCs), harmful contaminants to human health, have a strong sorption tendency to the airborne particles, which affects the SVOCs transport process in the air and increases the total SVOC concentration. In this paper, a mathematical model for describing the transport mechanism of SVOCs in the air and interactions with airborne particle was proposed. After validated by Benning et al. (2013)'s experimental results, the numerical results by the proposed model show that the particle-phase concentration of DEHP at the chamber outlet reduces rapidly when the air flow rate is higher than 400 mL/min, the particles will go on sorbing/desorbing DEHP in the sampling trains downstream the chamber, smaller particles lead to a higher concentration of particle-phase DEHP in the chamber, and a larger chamber leads to a higher steady-state concentration but a slower process that the DEHP concentration reaches steady-state. Besides, there is a certain range for air flow rate in different chambers, e.g. 100–1000 mL/min in this study, to ensure the sorption of DEHP onto particles reaching the gas-/particle-phase equilibrium and reduce the errors induced by the deposition of particles.

Ozone reacts with C–C double bonds in common indoor VOCs and SVOCs contained in indoor dust and may be catalytically degraded on dust surfaces. The reaction between floor dust and ozone was investigated in the FLEC emission cell at different ozone concentrations and relative humidities (0%, 25%, and 50% RH). One gram of dust was spread on a clean stainless steel plate which was placed in the FLEC. Steady state reaction rate (kDust) at 2.2ppm ozone was determined for four different floor dust samples collected in Danish homes and offices. This high concentration was necessary in order to measure and determine the consumption in the outlet air from the FLEC. Measurements were corrected for FLEC wall effects by subtraction of the steady state reaction rate between ozone and a FLEC on a stainless steel plate without dust (kFLEC). The composition of organic compounds in the dust was analyzed by pressurized liquid extraction and thermal desorption GC–MS before and after ozone exposure. kFLEC was independent of the ozone concentration and the reaction was treated as first order. The same was indicated for kDust since it remained unchanged at 2.2 and 1.6ppm ozone for one dust sample. However, the measured kDust in the FLEC should be considered an average rate constant due to the FLEC geometry. kDust was in the range 0.039–0.14s-1 pr. g dust at 50% RH. kDust was 3 times higher at 25% RH than at 50% RH and 6 times higher than at 0% RH. The inhomogeneity of the dust was assessed by experiments in triplicate with a new portion of dust each time. The relative standard deviation of kDust at 50% RH was 6–20%. The major identified compounds before and after ozone exposure included aldehydes, saturated and unsaturated linear alkanoic acids, benzoic acid and their methyl esters, dimethyl esters, phthalates and traces of α-pinene and limonene. Substantial increase of C7–C9 aldehydes was observed after ozone exposure.

The description of emission processes of volatile and semi-volatile organic compounds (VOCs and SVOCs) from building products requires a detailed understanding of the material and the air flow conditions at the surface boundary. The mass flux between the surface of the material and air depends on the mass transfer coefficient (hm) through the boundary layer, the gas phase concentration of the target compound immediately adjacent to the material (y0), and the gas-phase concentration in bulk air (y(t)). In the present study emission experiments were performed in two chambers of quite different sizes (0.25m3 and 55m3), and, in the larger chamber, at two different temperatures (23°C and 30°C). The emitting material was latex wall paint that had been doped with two plasticizers, diethylphthalate (DEP) and di-n-butylphthalate (DnBP). The phthalate content in the paint was varied in the small chamber experiment to evaluate the impact of the initial concentration in the bulk material (C0) on the emission rate. Boundary layer theory was applied to calculate hm for the specific phthalates from the Sherwood number (Sh) and the diffusion coefficient (Dair). Then y0 was determined based on the bulk gas-phase concentration at steady state (y¯). For both, DEP and DnBP, the y0 obtained was lower than the respective saturation vapor pressure (Ps). Furthermore, for both phthalates in latex paint, the material/air partition coefficient (C0/y0) was close in value to the octanol/air partition coefficient (KOA). This study provides a basis for designing phthalate emitting reference materials that mimic the emission behavior of common building materials.

Analysis of literature data published in the last few years leads to the conclusion that in the process of assessment of emission flux of organic compounds emitted from different types of equipment and finishing materials, new types of devices, among which small-scale passive emission chambers for the performance of in-situ research are designed and applied on a larger scale. These devices can be successfully used for the assessment of emission flux of organic compounds in any location of an apartment, with no interference with its normal exploitation. In the following article the possibility of application of a designed and constructed small-scale passive emission chamber for the evaluation of emission flux of organic compounds (mainly monoterpenes) emitted from the surface of wood-based material made of laminated chipboard has been presented. The emission chamber made from polished stainless steel of the inner volume of 3.65dm3 allows for the examination/assessment of emission flux from the surface of 452cm2. A diffusive passive sampler was installed inside of the small-scale chamber, which enables collecting samples of the analytes emitted from the examined surface of indoor material. The working time of the passive emission chamber equaled 300min. The results of preliminary studies show that, the constructed device can be successfully used for screening studies, related with the determination of emission flux of monoterpenes from any type of wood-based flat surface located indoors.

The widespread use of flame retardants (FRs) in indoor products has led to their ubiquitous distribution within indoor microenvironments with many studies reporting concentrations in indoor air and dust. Little information is available however on emission of these compounds to air, particularly the measurement of specific emission rates (SERs), or the migration pathways leading to dust contamination. Such knowledge gaps hamper efforts to develop understanding of human exposure. This review summarizes published data on SERs of the following FRs released from treated products: polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), tetrabromobisphenol-A (TBBPA), novel brominated flame retardants (NBFRs) and organophosphate flame retardants (PFRs), including a brief discussion of the methods used to derive these SERs. Also reviewed are published studies that utilize emission chambers for investigations/measurements of mass transfer of FRs to dust, discussing the chamber configurations and methods used for these experiments. A brief review of studies investigating correlations between concentrations detected in indoor air/dust and possible sources in the microenvironment is included along with efforts to model contamination of indoor environments. Critical analysis of the literature reveals that the major limitations with utilizing chambers to derive SERs for FRs arise due to the physicochemical properties of FRs. In particular, increased partitioning to chamber surfaces, airborne particles and dust, causes loss through “sink” effects and results in long times to reach steady state conditions inside the chamber. The limitations of chamber experiments are discussed as well as their potential for filling gaps in knowledge in this area.

While indoor air quality issues have received increasing attention the past decades, detailed investigations of primary sources of indoor pollution are still difficult to carry out. There is a lack of analytical tools and measurement procedures to identify sources of pollutants and to characterize their emissions. Formaldehyde is a ubiquitous pollutant in indoor environments, which is known to lead to adverse health effects. This study describes a measurement procedure to apportion formaldehyde emissions from building and furnishing materials and presents a source apportionment study performed in French public schools. More than 29 sources of formaldehyde were characterized in each investigated classroom, with higher emissions from building materials compared to furnishing materials. Formaldehyde emission rates measured using passive flux samplers (PFS) range from 1.2 to 252 μg/m2/h, highlighting several strong emitters made of wood products and foam. Interestingly, the ceiling was identified as the main source of formaldehyde in most classrooms. Measured emissions and air exchange rates were constrained in a mass balance model to evaluate the impact of formaldehyde reduction strategies. These results indicate that formaldehyde concentrations can be reduced by 87–98% by removing or replacing the main source of emission by a less emissive material and by increasing the air exchange rate to 1 h−1. In addition, an intercomparison of total emissions calculated from (1) PFS measurements and from (2) measured formaldehyde concentrations and air exchange rates indicate that an unidentified sink of formaldehyde may exist in indoor environments.

Indoor handling of large amounts of plant materials occurs in different occupational settings including greenhouses and causes exposure to bioaerosols. The bioaerosol components fungi, β-glucan, bacteria and endotoxin are involved in different airway symptoms and health effects can be dose-dependent. Therefore, there is a persistent need to reduce exposure. The aims of this study were to identify tasks causing exposure and to evaluate preventive measures aimed at reducing exposure of greenhouse workers to bioaerosols, and to study factors affecting the exposure. We have focused on different exposure scenarios; one with high short-term exposure found during clearing of old cucumber plants; the other with long-term, mid-level exposure found during tomato picking, leaf nipping, stringing up tomato plants, and packaging of cucumbers. Clearing of non-dried cucumber plants compared with clearing of dried cucumber plants significantly reduced the exposure to dust, endotoxin, bacteria, fungal spores and β-glucan. More endotoxin and fungi are emitted and more of the emitted particles were of respirable size if the leaves were dried. Along the cucumber packaging line, exposure levels were highly specific to each personal subtask. The subtask ‘unloading of cucumbers’ was the source of exposure making task ventilation or shielding of the process a possibility. Elimination of leaf debris on the floor reduced the exposure to fungi significantly. However, leaf debris on the floor did not contribute significantly to the exposure to dust, endotoxin and bacteria. Furthermore, to eliminate leaf debris, it had to be cleared away and this was associated with a higher exposure to dust and endotoxin. The age of the plants affected the exposure level to bioaerosols with higher exposures from old plants. In conclusion, different tasks and subtasks cause very different exposure levels. It is possible to reduce exposure by identifying subtasks causing the exposure and by modifying work processes, e.g., not drying out of plants.

This paper reports on first results from a recently finished project dealing with indoor air quality in timber constructed houses. The FLEC method was applied measuring single building products with respect to their emission of VOCs (i.e. volatile organic compounds) on a small scale. Furthermore, total emissions are investigated in full scale model rooms (30 m3) equipped with variable panel product types and coverings. It has been shown that the total VOC (TVOC) value, consisting of a heterogeneous mixture of single substances (from 25 up to 68 within the test setup), decreases significantly with duration time. Within one year, ranking of the TVOC emission level for 26 individual building products including wood based panels, plasterboards, flexible insulations, adhesives, vapour barriers and sealing sheets changed. Approximately 30% of the single substances formed 80% of the TVOC fraction. This actually highlights the complexity of indoor air emissions from building products. Full scale box trials allowed a direct comparison of OSB and OSB that was covered by gypsum plasterboard. Whereas the TVOC level immediately after construction is higher for uncovered OSB, values of both construction setups decline rapidly. After 14 days and onto 19 weeks, TVOC values were comparable for uncovered and covered OSB within the test. Hence, plasterboards have only a small effect on TVOC levels, but are not capable of reducing VOC emissions from building products.

The emission characteristic parameters of volatile organic compounds (VOCs) from paints are the initial concentration, the diffusion coefficient and the paint/air partition coefficient. It is necessary to determine these parameters for fully understanding the emission behaviors as well as for source control. Based on detailed mass transfer analysis of VOC emissions from paints, a novel method is developed to measure these parameters, which owns the following merits: (1) the diffusion coefficient and partition coefficient can be simultaneously determined; (2) it takes less than 12 h for the cases studied and indicates high measurement accuracy (R2 in the range of 0.921–0.939). Ventilated chamber experiments are performed to obtain the two parameters of methylcyclohexane and toluene emissions from one kind of solvent-based paint. The effectiveness of the method is verified by the good agreement between model predictions based on the determined characteristic parameters and experiments. The present approach is then applied to analyze the experimental data in the literature, and good results are also obtained, which further demonstrates that the approach is convincing and reliable. Our new approach should prove useful for rapid prediction and characterization of VOC emissions from paints as well as from other wet materials.

Cross-flow structured hollow fiber membrane bundles where the fibers are arranged either in inline or in staggered arrays are investigated for their bundle side convective mass transfer and pressure drop characteristics. A high speed hot wire anemometry is used to validate the turbulent flow behavior in the bundle at low Reynolds numbers. A mathematical model for the turbulent fluid flow and convective mass transfer across the bundle under uniform mass boundary conditions is set up, which is then validated by an air humidification test. With the validated model, the Sherwood numbers and friction factors across the bundle are obtained for different fiber arrangements, pitch to diameter ratios, and Reynolds numbers. Correlations are then proposed to estimate the friction factors and Sherwood numbers across the bundles with various parameters. It is found that compared to the previous researches and the available correlations, the present results are more appropriate for the cross flow hollow fiber membrane bundles that are usually operated under low Reynolds numbers from 100 to 500, but have turbulent flow behaviors.

Air pollution surveys of formaldehyde (HCHO) were conducted in 2324 rooms decorated within one year in 2007–2009 in Hangzhou, China. The mean HCHO concentration (CHCHO) was 0.107 ± 0.095 mg/m3, and 38.9% of samples exceeded the Chinese National Standard GB 50325-2010. Over the past 3 years, the CHCHO decreased with time (p < 0.05). Relationships of potential factors to indoor CHCHO were also evaluated. CHCHO was related to temperature (T), relative humidity (RH), time duration of the windows and doors being closed before sampling (DC), time duration from the end of decoration to sampling (DR) and source characteristics (d). A model to relate indoor CHCHO to these five factors (T, RH, DC, DR, d) was established based on 298 samples (R2 = 0.87). Various factors contributed to CHCHO in the following order: T, 43.7%; d, 31.0%; DC, 10.2%; DR, 8.0%; RH, 7.0%; specifically, meteorological conditions (i.e., RH plus T) accounted for 50.7%. The coefficient of T and RH, RTH, was proposed to describe their combined influence on HCHO emission, which also had a linear relationship (R2 = 0.9387) with HCHO release in a simulation chamber test. In addition, experiments confirm that it is a synergistic action as T and RH accelerate the release of HCHO, and that is a significant factor influencing indoor HCHO pollution. These achievements could lead to reference values of measures for the efficient reduction of indoor HCHO pollution.

Formaldehyde is a commonly observed indoor air contaminant with proved health effects. For the control of indoor formaldehyde, quick methods applicable in actual buildings are needed to identify the emission sources and estimate overall emission rates. The concentration decay and increase patterns with windows open or closed must also be studied to devise control strategy guidelines for natural ventilation in buildings. In this paper, a quick and easy-to-use method was introduced to identify the emission sources and estimate the overall emission rate resulting from all the emission sources. The method was applied to an apartment unit with multiple formaldehyde sources and showed promising applicability. The formaldehyde concentration decay patterns with different window opening degrees were measured and compared with the concentration increase patterns with closed windows. The results confirmed that natural ventilation through window opening can quickly remove indoor contaminants, and that the time scale of formaldehyde concentration increase is much bigger than that of decay patterns. The results imply that in control of indoor contaminant, natural intermittent ventilation by opening and closing windows is applicable.

Semi-volatile organic compounds (SVOCs) have been attracting more and more attentions to many researchers in these years. Because SVOCs have a strong tendency for adsorption to suspended particles, we take the effect of suspended particles into account to study the transport mechanism of SVOCs in the air. We establish a mathematical model to describe the transport mechanism of SVOCs, and study the transport processes of both gas- and particle-phase di-2-ethylhexyl phthalate (DEHP) in Field and Laboratory Emission Cells (FLECs). The predictions by the proposed model not only fit well with the experimental data of previous studies, but also show that the gas-phase DEHP concentration increases rapidly in the first few seconds and increases slowly during the following 200 days due to different transport mechanisms in the two periods. Meanwhile, when the particle radiuses are of the order of micron and the air changes per hour (ACH) is large enough, the characteristic time for DEHP getting gas/particle equilibrium is much longer than the residence time of a particle in the flow field, and thus there is no significant influence of suspended particles on the total concentration of DEHP in the air. Oppositely, the influence of particles on DEHP emission will be enhanced for a cycling air flow system with a small ACH, where increasing ACH will reduce the concentrations of particle-phase SVOCs. Besides, if the particle radiuses are of the order of nanometer, decreasing the particle radiuses will shorter the characteristic time for DEHP getting gas/particle equilibrium, and finally increase the particle-phase concentration of DEHP.

This study evaluates FLEC sampling for collecting volatile forensic attribution signatures and residues from building materials. Tests on metal, Teflon and vinyl flooring demonstrate the method's potential for non-destructive field sampling after chemical incidents.

Formaldehyde and TVOC emission factors from paints and coating materials were evaluated. The study applies the Field and Laboratory Emission Cell (FLEC) method used in Europe as an alternative to a 20 L small-chamber method.

The goal of this study is to extend sampling by the field and laboratory emission cell (FLEC) dynamic headspace technique to applications that target nonvolatile residues. On-matrix derivatization of residues to render analytes stable and more volatile is explored to achieve this goal. Results show that on-matrix derivatizations of nerve agent hydrolysis products (monoalkyl methylphosphonic acids and methylphosphonic acid [MPA]) with diazomethane were successful on glass and painted wallboard (at the 10-μg level). It also was successful on the more difficult concrete (at the 500-μg level) and carpet (at the 20-μg level), substrates that cannot be successfully sampled using swipe techniques. Analysis of additional chemical warfare (CW)-associated residues can be approached by on-matrix derivatization with trifluoroacetic anhydride (TFAA). For example, amines (used as stabilizers or present as decomposition products of the nerve agent VX) or thiodiglycol (hydrolysis product of sulfur mustard) could be sampled as their TFAA derivatives from glass, painted wallboard, and concrete (at the 40-μg level), as well as carpet (at the 80-μg level) surfaces. Although the amine and thiodiglycol are semi-volatile and could be sampled directly, derivatization improves the recovery and chromatographic behavior of these analytes.

Abstract: Among the many chemicals found indoors, semivolatile organic compounds (SVOCs) constitute an important class. While certain SVOCs are associated with adverse health effects, exposure is strongly influenced by the types of materials and products in which these SVOCs occur. This chapter begins with a brief summary of phthalates and flame retardants, two important types of SVOCs. Chamber experiments used to characterize the emissions process are then reviewed. A simple emission model that can be used to predict the steady-state indoor gas-phase SVOC concentration is described. Knowing the long-term concentration in the indoor air, the potential exposure via inhalation of air and airborne particles, ingestion of dust, and dermal absorption can be calculated using general relationships.

Adults spend most of their time in enclosed spaces (e.g., apartment, office and public buildings). According to research conducted by scientists, air quality indoors is much worse than the ambient air quality outdoors. Hazardous chemicals found in air indoors can adversely affect the functioning of the human body and cause many respiratory and circulatory diseases. Harmful chemical compounds (mainly volatile organic compounds and semi-volatile organic compounds) in the indoor environment are present because they are emitted from building and construction materials, and indoor equipment. One way of determining the levels of emissions of harmful chemicals is to use emission test chambers (ETCs), which can optimize analytical parameters (e.g., temperature, humidity, loading factor of the test chamber and the air-exchange rate). This article reviews the literature on the analytical methodologies that are used for different types of ETC for estimating emissions of chemicals from building and construction materials and components of indoor equipment.

Wooden building products indoors are known to be able to affect the perceived air quality depending on their emission strength. The indoor application of modern ecological lacquer systems (eco-lacquers or ‘green’ lacquers) may be a much stronger source than the substrates itself. Especially with regard to the formation of ultrafine particles by gas-to-particle conversion in the presence of ozone or other reactive species the impact of the applied building products on the indoor air quality has to be addressed. The present study reports a two concentration step ozonation of OSB panels, painted beech boards, and a number of solid ‘exotic’ wood types in a 1m³ emission test chamber. The emission of volatile organic compounds (VOC) was recorded as well as the formation of ultrafine particles in the range 7–300nm. The products are characterized on the basis of their ozone deposition velocity; the obtained values of 0.008–0.381cms−1 are comparable with previously published data. Within the samples of the present study one eco-lacquer was the strongest source of VOC (total VOC∼60mgm−3) while the wooden building products (OSB) were of intermediate emission strength. The lowest emission was found for the solid (exotic) wood samples. The VOC release of the samples corresponded roughly to the particle formation potential. However, the strongest UFP formation was measured for one solid wood sample (‘Garapa’) which showed a strong surface reaction in the presence of ozone and formed a large number of particles <40nm. Overall, the experiments demonstrated the necessity of real-life samples for the estimation of UFP indoor air pollution from the ozone chemistry of terpenes.

Abstract: Volatile organic compounds (VOCs) are an important class of indoor air pollutants; with indoor concentrations generally higher than outdoors. Formaldehyde is a priority VOC because of its frequent occurrence in indoor air and the serious health outcomes resulting from exposure. Taking formaldehyde as a representative VOC, this chapter reviews the knowledge necessary to develop solutions to indoor VOC pollution. The toxicology of formaldehyde is briefly reviewed. Then the current understanding of VOC emission behavior is discussed, including experimental techniques for measuring emissions, modeling approaches for predicting emissions, and the impacts of environmental factors on emissions. With a comprehensive understanding spanning emission characteristics and toxicology, it is possible to develop effective strategies to maintain indoor VOC concentrations below a safe threshold.

In this study, formaldehyde emission (FE) and content (FC) from different types of wood-based panels mainly; particleboard (PB), medium and high density fiberboard (MDF and HDF) and plywood (PLW) and flooring materials [HDF laminate, solid wood, solid bamboo and polyvinyl chloride (PVC)] were measured using different test methods namely; European small-scale chamber (EN 717-1), gas analysis (EN 717-2), the American small-scale chamber (ASTM D 6007-02), and the perforator (EN 120) methods. FE was affected with high significance by board type and thickness of PB (P < 0.0001), but there was no significant effect from the moisture content (MC %) of PB (P = 0.94) and PLW (P = 0.195). The corrected FC values measured EN 120 were declined when the MC % decreased. Furthermore, the liberation of formaldehyde was enhanced by the process of painting when 200 g/m2 oil-based paint was applied for MDF and HDF. There was a strong positive correlation among the four test methods (R2 values ranged between 0.88 and 0.94) concerning the formaldehyde values from PB-16 mm, and approximately the same indication of formaldehyde values, as well as similar behavior, were seen for each method. Moreover, the results indicate surprisingly that there was a good correlation between EN 120 and ASTM D 6007-02, with R2 values of 0.93. The measurements of FE from flooring panels were ranged between 0.003 and 0.125 mg/m3 and the PVC flooring with UV-curable layer only had emissions ranged between 0.003 and 0.008 mg/m3 as measured by EN 717-1. Values of the emittable formaldehyde concentrations from most of the products investigated in the present study were below the limits that are mandatory in the Czech Republic.

The present study investigated the indoor concentrations of selected volatile organic compounds (VOCs) and formaldehyde and their indoor emission characteristics in newly-built apartments at the pre-occupancy stage. In total, 107 apartments were surveyed for indoor and outdoor VOC concentrations in two metropolitan cities and one rural area in Korea. A mass balanced model was used to estimate surface area-specific emission rates of individual VOCs and formaldehyde. Seven (benzene, ethyl benzene, toluene, m,p-xylene, o-xylene, n-hexane, and n-heptane) of 40 target compounds were detectable in all indoor air samples, whereas the first five were detected in all outdoor air samples. Formaldehyde was also predominant in the indoor air samples, with a high detection frequency of 96%. The indoor concentrations were significantly higher than the outdoor concentrations for aromatics, alcohols, terpenes, and ketones. However, six halogenated VOCs exhibited similar concentrations for indoor and outdoor air samples, suggesting that they are not major components emitted from building materials. It was also suggested that a certain portion of the apartments surveyed were constructed by not following the Korean Ministry of Environment guidelines for formaldehyde emissions. Toluene exhibited the highest emission rate with a median value of 138μgm−2h−1. The target compounds with median emission rates greater than 20μgm−2h−1 were toluene, 1-propanol, formaldehyde, and 2-butanone. The wood panels/vinyl floor coverings were the largest indoor pollutant source, followed by floorings, wall coverings, adhesives, and paints. The wood panels/vinyl floor coverings contributed nearly three times more to indoor VOC concentrations than paints.

Experimental and numerical combined studies were carried out to investigate the effects of membrane properties and operating condition on water vapor (moisture) permeation through membranes. Experiments were conducted with water vapor transferring from a highly to a less humid air across membrane due to the water vapor concentration difference between the two sides of membrane, and numerical simulations were performed to simulate such process. The transmembrane moisture transfer was characterized using the moisture transfer resistance through membrane as well as the total moisture resistance, which include the membrane resistance and the boundary layer resistance on the two sides of membrane. The uniqueness of this research was a systematic examination of the effects of various membrane parameters and operating condition on the moisture permeation through membranes by combining the experiments and simulations. Tests were done on two membranes including the PVDF and PES membranes. The moisture diffusivities in these membranes were determined by comparing the experimental and numerical total moisture resistances. The results show that the moisture diffusivities in the PVDF and PES membranes are in the order of 10−6kgm−1s−1, with the PVDF yielding a larger diffusivity than the PES membrane. The moisture diffusivity in membrane, the maximum water uptake of membrane, and the sorption constant of membrane all have significant effects on the membrane resistance, with a high diffusivity, a large water uptake, and a proper sorption constant leading to a small membrane resistance, while the effects of the air entering humidity and airflow rate on the membrane resistance are dependent on the sorption constant. These results may help for the selection of the membrane materials.

The ongoing health debate about polymer plasticizers based on the esters of phthalic acid, especially di(2-ethylhexyl) phthalate (DEHP), has caused a trend towards using phthalates of lower volatility such as diisononyl phthalate (DINP) and towards other acid esters, such as adipates, terephthalates, citrates, etc. Probably the most important of these so-called “alternative” plasticizers is diisononyl cyclohexane-1,2-dicarboxylate (DINCH). In the indoor environment, the continuously growing market share of this compound since its launch in 2002 is inter alia apparent from the increasing concentration of DINCH in settled house dust. From the epidemiological point of view there is considerable interest in identifying how semi-volatile organic compounds (SVOCs) distribute in the indoor environment, especially in air, airborne particles and sedimented house dust. This, however, requires reliable experimental concentration data for the different media and good measurements or estimates of their physical and chemical properties. This paper reports on air concentrations for DINP, DINCH, diisobutyl phthalate (DIBP), diisobutyl adipate (DIBA), diisobutyl succinate (DIBS) and diisobutyl glutarate (DIBG) from emission studies in the Field and Laboratory Emission Cell (FLEC). For DINP and DINCH it took about 50days to reach the steady-state value: for four months no decay in the concentration could be observed. Moreover, vapor pressures p0 and octanol–air partitioning coefficients KOA were obtained for 37 phthalate and non-phthalate plasticizers from two different algorithms: EPI Suite and SPARC. It is shown that calculated gas/particle partition coefficients Kp and fractions can widely differ due to the uncertainty in the predicted p0 and KOA values. For most of the investigated compounds reliable experimental vapor pressures are not available. Rough estimates can be obtained from the measured emission rate of the pure compound in a microchamber as is shown for di-n-butyl phthalate (DnBP), di(2-ethylhexyl) adipate(DEHA), tri(octyl) trimellitate (TOTM) and DEHP.

Bioaerosols include viruses, bacteria, fungi, pollen, and their fragments as well as animal allergens. Bioaerosol exposure is common in indoor and outdoor environments and may cause infections, allergies, irritation, and toxic effects. The size of biological particles varies widely, from nanoscale (virions and microbial fragments) to approximately 100μm (pollen grains). The same physical principles that are applied to nonbiological particles can be applied to bioaerosol sampling in terms of sampling efficiency of a given particle size range. When sampling bioaerosols for exposure assessment purposes, one has to consider what biological property would be the most relevant measure for the health effect in question. Cultivation and microscopic counting are traditional analytical methods, but recently several new methods are emerging that are based on chemical, biological, or immunochemical analysis of bioaerosol components. Data interpretation is based on comparisons of results in target and reference areas or populations. When comparing data with previously published values, only results that are obtained using the same methodology should be directly compared.

A new approach for estimating chemical emissions from wet products has been developed. The concept of such approach is that emission rates can be estimated from the amount of target chemicals in the product as a function of evaporation time. Samples were placed under a laboratory fume hood under controlled conditions (surface air velocity and temperature). Weight losses of the product were monitored and residuals at different time intervals were chemically analyzed. Emission factors of the target chemicals were then calculated based on the weight losses and residual levels of the chemicals. To demonstrate the applicability of this approach, two wet products with very different physical characteristics, one liquid and one paste-like viscous fluid, were chosen. Emissions of two principle chemicals in the products, decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) were measured. The influences of initial sample weight, surface air velocity, and temperature were investigated. The calculated emission profiles were compared with those obtained from the chamber method. The described approach could be used as an alternative screening method for emission tests of wet products, especially for compounds with low vapour pressure when sink effect poses serious challenge in traditional chamber-based emission tests.

Formaldehyde was measured with a desiccator, a 20L chamber and the FLEC method. The formaldehyde emission rate from laminate was the highest at 32°C using the desiccator, which then decreased with time. The formaldehyde emission using the 20L small chamber and FLEC showed a similar tendency. There was a strong correlation between the formaldehyde and total volatile organic compounds (TVOCs) with both types of floorings using the two different methods. The formaldehyde emission rate and TVOC results were higher when tested using the FLEC method than with the 20L small chamber method. The emission rate was affected by the joint edge length in laminate flooring. Toluene, ethylbenzene and xylene were the main VOCs emitted from laminate flooring, and there were more unidentified VOCs emitted than identified VOCs. The samples heated with a floor heating system emitted more formaldehyde than those heated using an air circulation system due to the temperature difference between the bottom panel and flooring. The TVOC emission level of the samples was higher when an air circulation system was used than when a floor heating system was used due to the high ventilation rate.

Various experiments, such as the thermal extract (TE) method, field and emission cell (FLEC) method and 20L small chamber, were performed to examine the total volatile organic compound (TVOC) emissions from bio-composites. The TVOC of neat poly(lactic acid) (PLA) was ranged from 0.26mg/m2h to 4.11mg/m2h with increasing temperature. For both PLA bio-composites with pineapple flour and destarched cassava flour, the temperature increased from 0.30mg/m2h to 3.72mg/m2h and from 0.19mg/m2h to 8.74mg/m2h, respectively. The TVOC emission factors of all samples increased gradually with increasing temperature. Above 70°C, both PLA-P and PLA-C composites had higher TVOC emission factors than neat PLA due to the rapid emission of natural volatile organic compounds (VOCs), such as furfural (2-furancarboxyaldehyde). PLA composites containing 30wt% flour had high 1,4-dioxane reduction ability, >50%. The TVOC of poly(butylene succinate) (PBS) was emitted rapidly from 50°C to 90°C due to succinic acid from the pyrolysis of PBS. The TVOC emission factors of PLA bio-composite and PBS bio-composites were reduced using the bake-out method (temperature at 70°C and baking time 5h). The initial TVOC emission factors of the PLA and PBS bio-composites with pineapple flour and destarched cassava flour were reduced by the baking treatment using FLEC. The TVOC factors from PLA and PBS decreased until 5 days and were commonly maintained a relatively constant value after 5 days using 20L small chamber. The decrease in TVOC emission showed a similar trend to that of the TE and FLEC method. This method confirmed the beneficial effect of the baking treatment effect for polypropylene and linear density polyethylene (LDPE).

Indoor environments are dynamic reactors where consumer products (such as cleaning agents, deodorants, and air fresheners) emit volatile organic compounds (VOCs) that can subsequently interact with indoor oxidants such as ozone (O3), hydroxyl radicals, and nitrate radicals. Typically, consumer products consist of mixtures of VOCs and semi-VOCs which can react in the gas-phase or on surfaces with these oxidants to generate a variety of oxygenated products. In this study, the reaction of a pine-oil cleaner (POC) with O3 (100ppb) on a urethane-coated vinyl flooring tile was investigated at 5% and 50% relative humidity. These results were compared to previous α-terpineol+O3 reactions on glass and vinyl surfaces. Additionally, other terpene and terpene alcohol mixtures were formulated to understand the emission profiles as seen in the POC data. Results showed that the α-terpineol+O3 reaction products were the prominent species that were also observed in the POC/O3 surface experiments. Furthermore, α-terpineol+O3 reactions generate the largest fraction of oxygenated products even in equal mixtures of other terpene alcohols. This finding suggests that the judicial choice of terpene alcohols for inclusion in product formulations may be useful in reducing oxidation product emissions.

Membrane-based total heat exchangers (or energy recovery ventilators) are the key equipments to fresh air ventilation, which is helpful for the control of respiratory diseases like Swine flu and SARs. Cross flow has been the predominant flow arrangement for these equipments. However performances are limited with this arrangement. A counter flow arrangement is the best. In this research, a quasi-counter flow parallel-plates total heat exchanger is constructed and investigated. A detailed mathematical modeling is conducted and the model is experimentally verified. The temperature and humidity values on membrane surfaces, and in the fluids are solved as a conjugate problem. The fluid flow, heat and mass transport equations in the entry regions are solved directly. The mean Nusselt and Sherwood numbers, and the sensible and latent effectiveness of the exchanger are calculated. It is found that the effectiveness of the current arrangement lie between those for cross flow and those for counter flow arrangements. The results also found that the flow can be divided distinctly into three zones: two cross-like zones and a pure-counter flow zone. The less the cross-like zones are, the larger the pure-counter flow zone is, and the greater the effectiveness is. The study also provides a solution of modeling mass transfer with FLUENT software from heat mass analogy.

Formaldehyde and TVOC are emitted from wood-based panels that are made using wood particles, wood fiber, wood chips and formaldehyde-based resins. This study examined the formaldehyde and TVOC emission behavior of medium density fiberboard (MDF) overlaid with three types of uncoated lignocellulosic surface materials (oak decorative veneer, low pressure melamine impregnated paper and high pressure melamine impregnated paper) and four types of coated surface materials (coated paper, two types of finishing foils, and PVC) using the Field and Laboratory Emission Cell (FLEC) method and a 20L small chamber method. The uncoated lignocellulosic surface materials exhibited lower formaldehyde and TVOC emission levels. The coated surface materials did not show reduced TVOC emissions but the formaldehyde emission was reduced in the 20L small chamber test. In the FLEC test, both the uncoated lignocellulosic surface materials and coated surface materials showed lower TVOC and formaldehyde emissions from MDF.

The present study has been conducted in the frame of BUMA (Prioritization of Building Materials Emissions as indoor pollution sources), a European funded project, aiming at assessing the exposure to emitted compounds in indoor air. Field campaigns in five (5) European cities (Milan, Copenhagen, Dublin, Athens and Nicosia) were carried out. These campaigns covered weekly winter and summer concentration measurements in two (2) public buildings and two (2) private houses in each city. BTEX, terpenes, and carbonyls were measured using passive sampling in two sites inside the building and one outside. VOC emission measurements on selected building material have also been performed using Field and Laboratory Emission Cell (FLEC). The results on indoor concentrations for compounds such as formaldehyde (1.2–62.6μgm−3), acetaldehyde (0.7–41.6μgm−3), toluene (0.9–163.5μgm−3), xylenes (0.2–177.5μgm−3) and acetone (2.8–308.8μgm−3) have shown diversity and relatively significant indoor sources depending on the building type, age etc. Indoor concentrations of these substances are varied depending on the building age and type. The percentage of approximately 40% of the indoor air quality levels originated from building materials.

This paper assesses the reproducibility of testing formaldehyde and TVOC emission behavior from wood flooring composites bonded by urea–formaldehyde resin at various manufacturing steps for surface finishing materials. The surface adhesion step of laminate flooring for this research was divided into two steps; HDF only and HDF with LPMs. In the case of engineered flooring, the manufacturing steps were divided into three steps; plywood only, fancy veneer bonded on plywood and UV coated on fancy veneer with plywood. Formaldehyde and VOCs emission decreased at the process of final surface finishing materials; LPMs were applied on the surface of HDF for laminate flooring. Although emissions increased when fancy veneer was bonded onto plywood in the case of engineered flooring, emission was dramatically reduced up to similar level with plywood only when final surface finishing; UV-curable coating was applied on fancy veneer. This study suggests that formaldehyde and VOCs emission from floorings can be controlled at manufacturing steps for surface finishing.

The emission of di-(2-ethylhexyl)phthalate (DEHP) from one type of vinyl flooring with ∼15% (w/w) DEHP as plasticizer was measured at 22 °C in five FLECs + one blank FLEC (Field and Laboratory Emission Cell). Initially, the flow through all FLECs was 450 ml min−1. After 689 days the flows were changed to 1000 ml min−1, 1600 ml min−1, 2300 ml min−1, and 3000 ml min−1, respectively, in four FLECs, and kept at 450 ml min−1 in one FLEC. Air samples were collected from the effluent air at regular intervals. After 1190 days the experiments were terminated and the interior surfaces of all six FLECs were rinsed with methanol to estimate the internal surface concentrations of DEHP. The DEHP air concentration and specific emission rate (SER) at steady state was estimated for the five different flow rates. The steady-state concentrations decreased slightly with increasing air flow with only the two highest flow rates resulting in significantly lower concentrations. In contrast, the SERs increased significantly. Despite large variation, the internal surface concentrations appeared to decrease slightly with increasing FLEC flow. Computational fluid dynamic (CFD) simulations suggest that the interior gas and surface concentrations were roughly uniform for the low flow case (450 ml min−1), under which, the partitioning between the FLEC internal surface and chamber air was examined. Although paired t-tests showed no difference between CFD and experimental results for DEHP air concentrations and SERs at steady-state conditions, CFD indicated that the experimental DEHP surface concentrations in the FLECs were underestimated. In conclusion, the experiments showed that the emission of DEHP from vinyl flooring is subject to “external” control and that the SER is strongly and positively dependent on the air exchange rate. However, the increased SER almost compensates for the decrease in gas-phase concentration caused by the increased air exchange.

Formaldehyde and volatile organic compounds (VOCs) from the adhesive, flooring, and flooring with adhesive were measured using a desiccator, a 20-L chamber and a field and laboratory emission cell (FLEC). Flooring with an adhesive is similar to that used in construction was applied to a floor heating system and an air circulation system, and the surface temperature of the flooring was set to 20 °C, 26 °C and 32 °C. The rate of formaldehyde emission from the flooring was the highest at 32 °C using a desiccator and decreased with time. The formaldehyde and aldehyde emissions from the samples using a 20-L chamber and FLEC showed a similar tendency. The VOCs emission trends with the 20-L chamber and FLEC were similar. The rate of formaldehyde and TVOC emission determined using FLEC was higher than that determined using the 20-L chamber method. The flooring emitted primarily benzene, toluene, ethylbenzene, styrene, xylene, as well as some unknown VOCs. There was a strong correlation between formaldehyde and TVOC emission for the 20-L chamber and FLEC. Samples using a floor heating system showed higher formaldehyde emission than those using an air circulation system. The level of TVOC emission was higher from the samples using an air circulation system than those using the floor heating system.

This paper reviews different methods for the analysis of formaldehyde and volatile organic compounds (VOCs) from wood-based panel materials for furniture and building interiors and highlights research on reduction of emission from wood-based panels that can adversely affect indoor air quality. In Korea, standard test methods have been developed to determine formaldehyde and VOC emissions from building products, and the Ministry of Environment regulates the use of building materials with pollutant emissions. Desiccator and perforator methods are being used for formaldehyde and the chamber and field and laboratory emission cell (FLEC) methods for VOC and formaldehyde emissions. The VOC analyzer is a suitable pre-test method for application as a total VOC (TVOC) emission test and bake-out is a useful method to reduce TVOC and formaldehyde emissions from furniture materials in indoor environments.

The migration of di(2-ethylhexyl)phthalate (DEHP) from poly(vinyl chloride) (PVC) to a surrounding gas phase at temperatures below 120 °C kinetically is controlled by evaporation. The effects on the DEHP loss rate of nitrogen flow rate, relative humidity and degradation of the plasticizer at 100 °C was assessed. The sample mass decreased linearly with time for both pristine DEHP and plasticized PVC at comparable rates, suggesting that a thin film of DEHP was present on the jacketing insulation during desorption. The latter hypothesis was supported by infrared spectroscopy and by the fact that DEHP is an amphiphilic molecule that will tend to aggregate at the surface with the hydrophobic 2-ethylhexyl units at the air interface. The effect on the migration rate of moisture present in the gas phase was negligible. The DEHP loss rate increased in a retarding non-linear fashion with increasing gas flow rate. In one of the experiments, DEHP was accidently degraded as revealed by discoloration, the presence of low molar mass degradation products (liquid chromatography) containing additional carbonyl groups (infrared spectroscopy) and an increase in the evaporation rate at temperatures between 100 and 130 °C.

Volatile organic compounds (VOCs) emitted from building and furnishing materials are frequently observed in high concentrations in indoor air. Nondestructive analytical methods that determine the main parameters influencing concentration of the chemical substances are necessary to screen for sources of VOC emissions. Toward this goal, we have developed a new flux sampler, referred to herein as an emission cell for simultaneous multi-sampling (ECSMS), that is used for screening indoor emission sources of VOCs and for determining the emission rates of these sources. Because the ECSMS is based on passive sampling, it can be easily used on-site at a low cost. Among VOCs, low-molecular-weight carbonyl compounds including formaldehyde are frequently detected at high concentrations in indoor environments. In this study, we determined the reliability of the ECSMS for the collection of formaldehyde and other carbonyl compounds emitted from wood-based composites of medium density fiberboards and particleboards. We then used emission rates determined by the ECSMS to predict airborne concentrations of formaldehyde emitted from a bookshelf in a large chamber, and these data were compared to formaldehyde concentrations that were acquired simultaneously by means of an active sampling method. The values obtained from the two methods were quite similar, suggesting that ECSMS measurement is an effective method for screening primary sources influencing indoor concentrations of formaldehyde.

An experimental set-up was designed and constructed to investigate the moisture permeation through a membrane. The test section consists mainly of an airflow channel, a membrane, and a water tank, with the membrane being sandwiched between the channel and water tank. An air gap exists between the membrane and the water in the water tank to avoid any possible wetting of the membrane by the water. Moisture transfers from the water to the airstream in the channel through the air gap and membrane. The moisture transfer process was described using a serial resistance model, which involves the convective moisture resistance in the channel, the moisture resistance through membrane, and the moisture resistance caused by the air gap. Special methods were developed to determine the convective and air gap resistances, with the membrane resistance obtained by subtracting such two resistances from the total resistance. Tests were conducted on three membranes including the PVDF (poly vinylidene fluoride), PES (poly ether sulfone) and cellulose membranes for airflow rates from 3.0 to 5.0l/min, yielding Reynolds numbers from 117 to 195. The results showed that the moisture diffusivities in these membranes were in the order of 10−7 to 10−6kg/ms, with the PVDF yielding the maximum diffusivity and the PES giving the minimum diffusivity.

VOC emissions from model papers aged in closed tubes were quantified with a Field and Laboratory Emission Cell (FLEC) placed directly on the paper surface. The study applies FLEC to paper conservation and heritage-material analysis.

Chemical reactions on the surface of building materials can lead to secondary emissions from these materials that influence indoor air quality. Many studies have been made on the physical processes that influence material emissions. However, there are only a few studies on secondary emissions resulting from exposure of building material surfaces to ozone or ultraviolet (UV) irradiation. Therefore, this study was aimed at elaborating on the emission of chemicals resulting from chemical reactions initiated by the exposure of the surface of flooring materials to ozone or UV irradiation. The laboratory tests were conducted to estimate gas-phase emissions from the flooring materials when they were exposed to ozone or various kinds of light irradiation (infrared, sunlight, UV-A and UV-B lamps). The infrared and sunlight lamps significantly increased the temperature of the test specimens and, in turn, increased the emission rate for various organic compounds. The flooring materials used in this study had been treated with UV-cured surface coatings during their manufacturing. As a result, when exposed to UV irradiation, chemical transformations occurred resulting in the emission of a number of secondary products, including formaldehyde, acetaldehyde, cyclohexanone and benzaldehyde. Ozone reacted with chemicals present in the flooring materials to increase the emission rates of formaldehyde and acetaldehyde. Hence, the exposure of ozone and UV irradiation increased the secondary emissions of formaldehyde, even though the low formaldehyde emission type of flooring material was employed.

The surface-phase reaction products of dihydromyrcenol (2,6-dimethyl-7-octen-2-ol) with ozone (O3), air, or nitrogen (N2) on silanized glass, glass and vinyl flooring tile were investigated using the recently published FACS (FLEC (Field and Laboratory Emission Cell) Automation and Control System). The FACS was used to deliver ozone (100 ppb), air, or N2 to the surface at a specified flow rate (300 mL min−1) and relative humidity (50%) after application of a 2.0% dihydromyrcenol solution in methanol. Oxidation products were detected using the derivatization agents: O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) and N,O-bis(trimethysilyl)trifluoroacetamide (BSTFA). The positively identified reaction products were glycolaldehyde, 2,6-dimethyl-5-heptenal, and glyoxal. The proposed oxidation products based on previously published VOC/O3 reaction mechanisms were: 2,6-dimethyl-4-heptenal, 6-methyl-7-octen-2-one and the surface-specific reaction products: 6-methyl-6-hepten-2-one, 6-methyl-5-hepten-2-one, and 6-hydroxy-6-methylheptan-2-one. Though similar products were observed in gas-phase dihydromyrcenol/O3 reactions, the ratio, based on peak area, of the reaction products was different suggesting stabilization of larger molecular weight species by the surface. Emission profiles of these oxidation products over 72 h are also reported.

In indoor environments with high levels of air pollution, it is desirable to remove major sources of emissions to improve air quality. In order to identify the emission sources that contribute most to the concentrations of indoor air pollutants, we used passive flux samplers (PFSs) to measure emission rates of carbonyl compounds and volatile organic compounds (VOCs) from many of the building materials and furnishings present in a room in a reinforced concrete building in Tokyo, Japan. The emission flux of formaldehyde from a desk was high (125μg/m2/h), whereas fluxes from a door and flooring were low (21.5 and 16.5μg/m2/h, respectively). The emission fluxes of toluene from the ceiling and the carpet were high (80.0 and 72.3μg/m2/h, respectively), whereas that from the flooring was low (9.09μg/m2/h). The indoor and outdoor concentrations of formaldehyde were 61.5 and 8.64μg/m3, respectively, and those of toluene were 43.2 and 17.5μg/m3, respectively. The air exchange rate of the room as measured by the perfluorocarbon tracer (PFT) method was 1.84/h. Taking into consideration the area of the emission sources, the carpet, ceiling, and walls were identified as the principal emission sources, contributing 24%, 20%, and 22% of the formaldehyde, respectively, and 22%, 27%, and 14% of the toluene, respectively, assuming that the emission rate from every major emission sources could be measured. In contrast, the door, the flooring, and the desk contributed little to the indoor levels of formaldehyde (1.0%, 0.54%, and 4.1%, respectively) and toluene (2.2%, 0.31%, and 0.85%, respectively).

The objective of this research was to develop environment-friendly adhesives for face fancy veneer bonding of engineered flooring using the natural tannin form bark in the wood. The natural wattle tannin adhesive were used to replace UF resin in the formaldehyde-based resin system in order to reduce formaldehyde and volatile organic compound (VOC) emissions from the adhesives used between plywoods and fancy veneers. PVAc was added to the natural tannin adhesive to increase viscosity of tannin adhesive for surface bonding. For tannin/PVAc hybrid adhesives, 5%, 10%, 20% and 30% of PVAc to the natural tannin adhesives were added. tannin/PVAc hybrid adhesives showed better bonding than the commercial natural tannin adhesive with a higher level of wood penetration. The initial adhesion strength was sufficient to be maintained within the optimum initial tack range. The standard formaldehyde emission test (desiccator method), field and laboratory emission cell (FLEC) and VOC analyzer were used to determine the formaldehyde and VOC emissions from engineered flooring bonded with commercial the natural tannin adhesive and tannin/PVAc hybrid adhesives. By desiccator method and FLEC, the formaldehyde emission level of each adhesive showed the similar tendency. All adhesives satisfied the E1 grade (below 1.5mg/L) and E0 grade (below 0.5mg/L) with UV coating. VOC emission results by FLEC and VOC analyzer were different with the formaldehyde emission results. TVOC emission was slightly increased as adding PVAc.

Acetic and formic acid vapors emitted from woodwork in historical organs are very important corrosive agents for lead pipes. These acids are slowly released from the wood both during playing and when the pipes are silent. To inhibit this emission process, the wood surface can be modified, by creating a protective layer with alkaline features. However, a coating of wood is not recommended since this could modify the appearance and create a layer not perfectly compatible with the substrate. For this reason, we propose to use some innovative nanotechnology that has been successfully applied for the deacidification of wood samples coming from the Vasa shipwreck. Application of calcium (or magnesium) hydroxide nanoparticles, with sizes ranging from 30–150nm, allowed a homogeneous distribution of particles through the surface layer of wood simply by soaking (or spraying) it in a alcoholic (or mixed with less polar solvents) dispersion of nanoparticles. Nanoparticles do not modify the wood appearance and distribute randomly within the first layers of wood. The small size of particles accounts for the high reactivity with CO2 from the air, to give the alkaline reserve of carbonates that provide high efficacy in the neutralization of gaseous acids. The emission of volatile organic compounds (VOC) from the treated wood was determined by using an emission test cell, Field and Laboratory Emission Cell (FLEC). The results show that the emissions of acetic acid vapor from nanoparticles treated wood was very low (<70μg/m2h) during the first 13 month. In contrast, untreated wood emitted high concentrations of acetic acid vapor (200–400μg/m2h).

The FLEC^®-SPME sampler, described in a previous paper, consists of an emission cell coupled with solid phase microextraction (SPME) for passive sampling of VOCs emitted from building materials. It represents an interesting alternative to standard dynamic sampling protocol as it is easier to implement. If standard dynamic sampling determines emission rates, passive FLEC^®-SPME aims to the determination of the concentration in air at the material surface. That could be assumed provided that material/air equilibrium is reached. Thus, VOCs emission kinetics were studied for 3 different materials (pine wood panel, carpet and PVC floor) to determine equilibrium times. Then, the relevance of the method has been assessed using new materials through a 3-day emission test. Qualitative results were compared to those obtained from the standard method to check the ability of FLEC^®-SPME to detect the most toxic compounds, named “VOCs of interest” and listed in the French regulation. Minor differences were observed, so this methodology seems promising, especially for field studies aiming in the identification of VOCs sources in buildings. Moreover, the concentration at the material surface combined to emission modeling could be used to predict indoor VOCs concentrations helping in indoor air quality diagnostic.

2-Ethyl hexanol from hydrolysed di-octyl-phthalate (DOP) may cause a secondary emission from building products such as PVC carpets and/or glues causing indoor air pollution. In the present study, a micro-scale headspace vial (MHV) method, earlier developed by us, was refined to study the degradation of DOP and di-isononyl phthalate (DINP) in humid and alkaline environments. By HS-SPME it was possible to extract the degradation products at low temperature, 35°C, which limits the risks of unwanted degradation during sampling. Three different types of HS-SPME fibres were evaluated. The carbowax-divinyl benzene (CW/DVB) fibre had the highest extraction capacity of 2-ethyl-1-hexanol and 5-nonanol. Although significantly shorter extraction times could be used with the 7μm and 30μm poly-dimethylsiloxane (PDMS) fibres, the CW/DVB fibre was found to be the most suitable for these alcohols. Furthermore, it was found that pH of the alkaline environment strongly influences the formation of degradation products from DOP and DINP.

Formaldehyde and TVOC emissions from bio-composites with decorative veneer were measured using the Field and Laboratory Emission Cell (FLEC) method. The article directly applies FLEC to emission testing of wood-based bio-composites.

Emission rates of volatile organic compounds (VOCs) and ammonia measured from six PVC materials and four adhesives in the laboratory were compared to the emission rates measured on site from complete structures. Significantly higher specific emission rates (SERs) were generally measured from the complete structures than from individual materials. There were large differences between different PVC materials in their permeability for VOCs originating from the underlying structure. Glycol ethers and esters from adhesives used in the installation contributed to the emissions from the PVC covered structure. Emissions of 2-ethylhexanol and TXIB (2,2,4-trimethyl-1,3-pentanediol diisobutyrate) were common. High ammonia SERs were measured from single adhesives but their contribution to the emissions from the complete structure did not appear as obvious as for VOCs. The results indicate that three factors affected the VOC emissions from the PVC flooring on a structure: 1) the permeability of the PVC product for VOCs, 2) the VOC emission from the adhesive used, and 3) the VOC emission from the backside of the PVC product.

The study compares formaldehyde and TVOC emissions from engineered flooring bonded with MF/PVAc resin blends. FLEC is one of the principal test methods and is compared with a 20-litre chamber, a VOC analyser and the desiccator method.

Three-dimensional computational fluid dynamics is used to examine airflow and VOC emission fields inside a Field and Laboratory Emission Cell. The study evaluates FLEC performance for materials governed by internal, external and mixed diffusion.

A FLEC automation and control system was developed to deliver ozone to surfaces while continuously controlling ozone, humidity and airflow. The system was demonstrated by studying ozone reactions with alpha-terpineol on vinyl.

Asthma in children appears to be associated with both phthalate esters and dampness in buildings. An important question is whether the concentrations of phthalate esters correlate with dampness (expressed as relative humidity—RH) in indoor air. The objective was to study the influence of RH on the specific emission rate (SER) of di-(2-ethylhexyl)phthalate (DEHP) from one type of vinyl flooring in the well characterized Field and Laboratory Emission Cell (FLEC). The vinyl flooring with ca. 17% (w/w) DEHP as plasticizer was tested in 6 FLECs at 22°C. The RH in the 6 FLECs was 10%, 30%, 50% (in triplicate) and 70%. The RH was changed after 248d in 2 of the 50%-FLECs to 10% and 70%, and to 50% in the 10%-and 70%-FLECs. The data show that the SER of DEHP from vinyl flooring in FLECs during a 1yr period is independent of the RH. A new physically based emission model for semivolatile organic compounds was found to be consistent with the experimental data and independent of the RH. The model helps to explain the RH results, because it appears that RH does not significantly influence any of the identified controlling mechanisms.

Based on the most recently published mass transfer model of volatile organic compound (VOC) emissions from dry building materials, it is found that the dimensionless emission rate and total emission quantity are functions of just four dimensionless parameters, the ratio of mass transfer Biot number to partition coefficient (Bim/K), the mass transfer Fourier number (Fom), the dimensionless air exchange rate (Nδ2/Dm) and the ratio of building material volume to chamber or room volume (Aδ/V). Through numerical analysis and data fitting, a group of dimensionless correlations for estimating the emission rate from dry building materials is obtained. The predictions of the correlations are validated against the predictions made by the mass transfer model. Using the correlations, the VOC emission rate from dry building materials can be conveniently calculated without having to solve the complicated mass transfer equations. Thus it is very simple to estimate VOC emissions for a given condition. The predictions of the correlations agree well with experimental data in the literature except in the initial few hours. Furthermore, based on the correlations, a relationship between the emission rates of a material in two different situations is deduced. With this relationship, the results for a given building material in a test chamber can be scaled to those under real conditions, if the dimensionless parameters are within the appropriate region for the correlations. The relationship also explicitly explains the impacts of air velocity, load ratio, and air exchange rate on the VOC emission rate, which determines the feasibility of assuming that the VOC emission rates in real conditions are the same as those in the test chambers.

The effects of natural compounds on reducing formaldehyde emission from plywood were investigated. Urea, catechin and vanillin were examined as the natural formaldehyde reducers. The microemission cell, with an internal volume of 35ml, the maximum exposed test surface area of 177cm2 and an air purge flow rate of 50mlmin−1, was used to measure specific emission rate (SER). In the case of no reducer treatment, formaldehyde emission from plywood was fast and SERs were 4.4mgm−2h−1 at 30°C and 15mgm−2h−1 at 60°C. When this plywood was treated with the natural compounds, the SERs of formaldehyde were decreased at all temperatures. In the case of urea treatment, the SERs of formaldehyde decreased to 0.30mgm−2h−1 at 30°C and 0.65mgm−2h−1 at 60°C. When the urea treatment was applied to the inside of kitchen cabinet (made from plywood; 270cm wide, 60cm deep, 250cm high), the concentration of formaldehyde was reduced substantially from 1600 to 130μgm−3. The reducing effect of formaldehyde continued during the observation period (6 months), with a mean concentration of 100μgm−3. Reducers in the plywood would react with released formaldehyde. Application of natural compounds such as urea, catechin and vanillin could provide a simple and effective approach for suppressing formaldehyde emission from plywood.

A 3-year research project was established in 1999 to create numerical reference data for material emissions during the time of construction and during the first year. Seven buildings, representing the present construction practice in Finland, were investigated. Material emissions were measured by using the field and laboratory cell (FLEC) during the time of construction, in the newly finished, and in the 6- and 12-month-old buildings. The emission rates for volatile organic compounds (VOCs), formaldehyde, and ammonia were determined. The highest total VOCs (TVOC) emissions were measured in the newly finished buildings from the ceiling structure and from some of the PVC floor coverings. These emissions were up to 1300–2000μgm−2h−1. Individual VOCs with emission rates above 50μgm−2h−1 included 2-(2-butoxyethoxy) ethanol and its acetate, C4–C16-substituted alkylbenzenes, and xylenes. The mean TVOC emission decreased at least to the Finnish M1-class level (200μgm−2h−1) from all surfaces and in all the buildings in 6–12 months. The ammonia and formaldehyde emissions from the ceiling structure were 20–60μgm−2h−1 in the newly finished buildings and the M1-levels (30/50μgm−2h−1) were exceeded in some cases. These emissions even increased in some buildings during the follow-up period indicating the difference between emissions measured in the laboratory and on site from real structures. Reference values based on the means and 95th percentile are presented to be utilised in both quality control and while investigating indoor air quality problems which are suspected to be caused by a defect structure.

A new passive flux sampler (PFS) was developed to measure emission rates of formaldehyde and to determine emission sources in indoor environments. The sampler consisted of a glass Petri dish containing a 2,4-dinitrophenyl hydrazine (DNPH)-impregnated sheet. At the start of sampling, the PFS was placed with the open face of the dish on each of the indoor materials under investigation, such as flooring, walls, doors, closets, desks, beds, etc. Formaldehyde emitted from a source material diffused through the inside of the PFS and was adsorbed onto the DNPH sheet. The formaldehyde emission rates could be determined from the quantities adsorbed. The lower determination limits were 9.2 and 2.3μgm−2h−1 for 2- and 8-h sampling periods. The recovery rate and the precision of the PFS were 82.9% and 8.26%, respectively. The emission rates measured by PFS were in good agreement with the emission rates measured by the chamber method (R2=0.963). This shows that it is possible to take measurements of the formaldehyde emission rates from sources in a room and to compare them. In addition, the sampler can be used to elucidate the emission characteristics of a source by carrying out emission measurements with different air-layer thicknesses inside the PFS and at different temperatures. The dependency of the emission rate on the thickness of the air layer inside the PFS indicated whether the internal mass transfer inside the source material or the diffusion in the gas-phase boundary layer controlled the formaldehyde emission rate from a material. In addition, as a pilot study, the formaldehyde emission rates were measured, and the largest emission source of formaldehyde could be identified from among several suspected materials in a model house by using the PFS.

VOC emissions from building finishing materials are evaluated with several approaches. The paper explicitly compares formaldehyde and TVOC results from a small chamber with measurements made using the Field and Laboratory Emission Cell (FLEC).

This research focuses studies of water permeation potential through a polymer membrane with the help of a standard field and laboratory emission cell. Special efforts are devoted to finding a correlation governing the relations between the number of transfer units (NTU) and the moisture exchange effectiveness. As a first step, moisture diffusivity in the hydrophilic polymer membrane is experimentally measured. In combination with mathematical modeling, the moisture concentration distributions in the cell, the water uptake gradients in the membrane, as well as the local vapor emission rate on membrane surface, are investigated. The results are that the emission rates show a non-uniform character and a polynomial equation governing the moisture exchange effectiveness and the dimensionless number of transfer units, could be used to inversely estimate the diffusivity of water vapor in hydrophilic membranes. The form and the value of constants in the equation are obtained.

The diffusion and partition coefficients of eight volatile organic compounds (VOCs) in cement slabs were experimentally determined using a field and laboratory emission cell (FLEC) system based on the method developed in a previous study on the water vapor diffusion. A cement slab planted with a mixture of eight VOCs was placed in an one-FLEC system to undergo the mass diffusion in the slab and the emission to air flowing through the FLEC. The concentration of each VOC in the air flowing out of the FLEC was measured according to the EPA Method TO-17 using sorbent tube-automatic thermal desorption (ATD) and the gas chromatography-mass spectrum detector (GC-MSD) system. The diffusion and partition coefficients were then obtained by solving the inverse problem of the one-dimensional unsteady mass diffusion equations in the cement slab. And, the partition coefficient was also obtained from the total mass transfer estimated from the VOC concentration measurements and air flowrate, which was equivalent to the headspace concentration-weighting method.

Moisture diffusivity in hydrophilic membranes is measured traditionally by stepwise drying experiments or steady state permeation tests. Problems with these methods are that the convective moisture resistance in membrane boundary layers is seldom taken into account, and the distributed nature of moisture emissions on membrane surface and air concentration above it often give distorted results. In this study, a new method designed to overcome these imperfections is proposed in predicting the diffusivity of moisture in hydrophilic membranes. The key equipment is a filed and laboratory emission cell. The whole technique comprises two steps: in the first step, the cell surface convective mass transfer coefficient is obtained; and in the second step, moisture diffusivity in membrane is measured. The technique also involves a two-dimensional modeling of moisture transport in membranes.

Drying is a complex process to model. Certain assumptions, such as an isothermal process, a uniform temperature process and a heat transfer limiting process, where no mass transfer resistance is considered and so on. Lewis number (Le) is defined as the ratio of the thermal diffusivity to the mass diffusivity. It indicates if the heat and mass transfer processes are whether mass transfer limiting (Le≫1), heat transfer limiting (Le≪1), or are much coupled processes (Le∼1). The Lewis number for drying is calculated using the properties that may not be realistic, e.g. that by neglecting the effect of the water sorption capability of the material being dried. Sometimes, quite different conclusions on whether or not drying is limited by heat transfer can result. Here, two new approaches to Lewis number estimation are presented for hygroscopic materials. Sample calculations are made for milk particle drying as an illustration of the principles outlined.

Paints are widely used in residential and commercial buildings. The surface areas covered by this kind of coatings are usually very large. The volatile organic compounds (VOCs) emissions from such kind of materials will affect indoor air quality decisively. A relatively simple but physically-based model was developed to simulate VOCs emissions from paints. The model parameters have distinct physical meanings and thus the model is easy to scale up. The field and laboratory emission cell (FLEC) was used to investigate the VOCs emissions from commercially available water-based emulsion paint. Totally 23 individual VOCs were detected and quantified, the most abundant VOC was 1-ethyl-3-methylbenzene. Test data were used to obtain model parameters and to validate the proposed model. Good agreements between experimental data and model predictions were evidenced. Paints applied on two different substrates aluminium and particle board were simulated. Results indicated that real substrates like particle board would act like a ‘sponge’, which lowers the peak concentration but prolongs the presence of VOCs from the applied paint.

Water vapor diffusion and partition coefficients in cement slabs were determined by solving the inverse problem of one-dimensional unsteady mass diffusion based on measurements of the concentration of water vapor in a field and laboratory emission cell (FLEC) system. A solution for multi-process mass diffusion was obtained to analyze the influence of the non-uniform initial water vapor concentration distribution on the determination of diffusion and partition coefficients. The main factors affecting the accuracy of the diffusion and partition coefficients were discussed. Good agreement between the measured data and the predictions of the inverse problems showed that the mass diffusion in the cement slabs could be described accurately by the one-dimensional model.

Building envelopes are usually comprised of several layers with different materials, which can significantly affect volatile organic compounds (VOCs) concentrations in indoor environments. These layers may act as source and sink alternatively depending on the different sorption and diffusion potentials. The model proposed here is a single zone one and it considers the different emission properties of building components, namely, the different sorption and diffusion characteristics of the side walls, the floor and the ceiling. In addition, each component comprises of several layers, which represents different construction materials. Two VOCs, ethyl acetate and n-octane, representing polar and nonpolar compounds respectively, are modeled to study the emission profiles in a room with several building materials. The effects of various construction materials, and the different convective mass transfer coefficients between room air and different building components, on the emission characteristics are investigated.

VOC emission rates from paint were compared in a 1 m³ chamber, a Field and Laboratory Emission Cell (FLEC), and CLIMPAQ under matched area-specific ventilation rates and climatic conditions.

The field and laboratory emission cell (FLEC) is becoming a standard method of characterizing pollutant emissions from building materials. It is significant to use the emission profiles from FLEC to scale the emissions of building materials in real buildings. The dynamics of mass transfer in such an FLEC are the key to perform this task. In this study, the mass transfer mechanisms of the total volatile organic compounds from a wet painting in an FLEC are experimentally and numerically investigated. A three-dimensional mass transfer model, which takes into account the convective mass transfer between the material and the air, the diffusion in the paint film and in the substrate, is developed. The emissions from a water-based emulsion paint are quantified to assess the model. The concentration fields in the film and substrate are calculated to demonstrate the processes of internal volatile organic compounds diffusion.

Solvent-based interior coating materials have long been recognized as a major source of volatile organic compounds (VOCs) in the indoor environment. In the emission process, substrate acts as a secondary source. The sink effects are studied with a detailed mass transfer model considering convective mass transfer in air streams, the VOCs diffusions in painting film, and the sorption and diffusions of VOCs in substrate. The model is proposed and validated by the emission profiles of a water-based emulsion paint in a standard field and laboratory emission cell. The focus is on the role the substrate plays in the emission process. The effects of the substrate parameters, such as the substrate diffusivity and sorption characteristics, on the emission profiles are investigated. This is helpful in exposure control through both selecting healthy materials and proper ventilations.

The field and laboratory emission cell (FLEC) is becoming a standard method of characterizing pollutant emissions from building materials. Based on this method, the material and the inner surface of the FLEC cap form a cone-shaped cavity. The airflow is distributed radially inward over the test surface through a slit in a circular-shaped channel at the perimeter of the chamber. After mass transfer, the air is exhausted through an outlet in the center. Usually, emission rate profiles are obtained using such cells. However, the local convective mass transfer coefficients are now needed. In this study, laminar fluid flow and mass transfer in a standard FLEC are investigated. The velocity field and moisture profiles are obtained by solving Navier–Stokes equations numerically. The whole geometry, including the air inlet and outlet, channel, air slit, and emission space, are included in the numerical modeling domain. The mean convective mass transfer coefficients are calculated and compared with the experimental data. In the test, distilled water is used in the FLEC lower chamber to substitute the emission surface. Mass transfer data are obtained by calculating humidity differences between the inlet and outlet of a gas stream flowing through the FLEC. The study concentrates on assessing the variations of velocity and humidity profiles, as well as convective mass transfer coefficients, in the cell.

Fungal growth in buildings starts at a water activity (aw) near 0.8, but significant quantities of mycotoxins are not produced unless aw reaches 0.95. Stachybotrys generates particularly high quantities of many chemically distinct metabolites in water-damaged buildings. These metabolites are carried by spores, and can be detected in air samples at high spore concentrations. Very little attention has been paid to major metabolites of Stachybotrys called spirocyclic drimanes, and the precise structures of the most abundant of these compounds are unknown. Species of Aspergillus and Penicillium prevalent in the indoor environment produce relatively low concentrations of mycotoxins, with the exception of sterigmatocystins that can represent up to 1% of the biomass of A. versicolor at aw’s close to 1. The worst-case scenario for homeowners is produced by consecutive episodes of water damage that promote fungal growth and mycotoxin synthesis, followed by drier conditions that facilitate the liberation of spores and hyphal fragments.

UV-curable systems for manufacturing of furniture and parquet form a major and growing field in radiation curing. Numerous types and combinations of photoinitiators have been developed for crosslinking of acrylated systems and unsaturated polyesters. The properties of the photoinitiators being used in these materials must fulfill requirements like low toxicity, low odor and high reactivity. However, volatile reaction products being produced during the photochemical process contribute to the pollution of indoor air by emission from the surface and may cause strong odor and adverse health effects. Therefore, the release of photoinitiators, fragmentation products and monomers from UV-cured coatings was studied as a function of time under realistic living conditions in emission test chambers and cells. Main components detected in the chamber air were benzaldehyde, cyclohexanone, benzophenone and acrylate monomers. The area-specific emission rates SERA were found to be strongly dependent on the climatic conditions.

Publisher Summary Field and laboratory emission chamber (FLEC) is becoming a standard method to characterize pollutant emissions from building materials. This chapter examines the surface convective mass transfer coefficients in a standard FLEC. A cell employed for examination is composed of two parts—cap and lower cavity. The deepness of the lower cavity is 10mm. When testing, the material is placed on the bottom surface of the lower cavity and becomes an integral part of the emission cell. To investigate the mean and local mass transfer coefficients at different FLEC radius, five glass discs with thickness of 10mm and diameters ranging from 130 to 148mm, are prepared. In each test, a disc is placed onto the bottom surface and distilled water is filled in the space between the cell wall and the disc. The chapter finally presents experimentally obtained mean Sherwood numbers with different radius glass discs.

Ozone removal by 16 aged building products was studied with the Field and Laboratory Emission Cell. The work reports repeatable ozone-removal profiles and deposition velocities for materials including gypsum board, wood, concrete, linoleum and carpet.

Consumer products are important sources of human exposure to certain chemicals. Recent regulatory requirements for assessing human exposure to three glycol ethers, namely 2-methoxyethanol (ME), 2-ethoxyethanol (EE) and 2-butoxyethanol (BE), have prompted the investigation of these chemicals in consumer products and their emission characteristics. Thirteen products were selected for investigation based on their potential of containing the chemicals. Headspace results indicated that ME and EE were not present in any of the 13 selected products, while BE was detected in the headspace samples of seven products, of which five were household cleaning agents. Other related compounds such as 2-hexyloxyethanol (HE) and 2-(2-butoxyethoxy)ethanol (BEE) were also detected in the headspace samples of some products. BE emissions from five cleaning related products were measured using a field and laboratory emission cell (FLEC) with its subunit to provide emission data for inhalation exposure assessment purposes. These products had initial emission factors ranging from 145 to 938 mg m−2 h−1 under the experimental conditions. It was found that the emission factor of BE was inversely proportional to the dilution factor of the products. A good relationship was established between the emission factor of BE and its concentrations in water-based products. Based on product use scenarios developed by US EPA and an assumed “standard room,” average daily inhalation exposure levels of a resident as a result of performing cleaning tasks were estimated to be 0.075 and 0.186 mg (kg b.w.)−1 day−1 for two all-purpose spray cleaners, and 0.004 and 0.006 mg (kg b.w.)−1 day−1 for two-spray glass cleaners, respectively.

The concentrations of the aromatic hydrocarbons benzene, toluene, ethylbenzene and the isomeric xylenes (BTEX) have been determined in the indoor air of 115 private non-smoker homes (∼380 individual rooms) situated in areas with an extreme traffic situation, i.e. in city streets (street canyons) with high traffic density and in rural areas with hardly any traffic at all. The influence of the traffic on the indoor concentration was apparent in the high traffic area. In order to identify other factors influencing the BTEX concentrations, the data and additional questionnaires were analyzed by univariate and multivariate analysis. The analysis was supplemented by some case studies. It is shown that meteorology (the seasons), the type of room (e.g. living room versus bedroom), the ventilation and, in particular, garages in the house strongly influence the indoor concentration of BTEX. Thus, the indoor BTEX level is significantly higher in winter than in summer. Moreover, garages with a connecting door to the living quarters lead to high indoor concentrations of aromatic hydrocarbons in these rooms. In addition, the storage of solvents and hobby materials, and also the presence of smoking guests increase the BTEX level. If rooms are directly heated by coal or wood, the BTEX level is higher compared to the use of gas heating. Surprisingly, no correlation was found between the building materials used and the BTEX level. Case studies were carried out for two homes with an integrated garage (and a connecting door to the living rooms) and for seven homes where redecoration work was carried out during sampling. In both instances, a pronounced increase was observed in the BTEX concentration.

The FLEC method for determining formaldehyde emissions from wood-based building materials is compared with a traditional chamber method. The study reports good correlation and an average recovery of 98 percent for known formaldehyde sources.

Indoor air pollution caused by volatile organic compounds (VOCs) may affect the health and well-being of inhabitants. Uptake and release of these compounds by and from indoor materials alter their concentrations in indoor air: uptake will lower peak concentrations, whereas subsequent (slow) release at lower concentration levels will prolong the presence of VOCs in indoor air. An experimental set-up has been implemented where indoor materials are placed as a “membrane” separating two air compartments. Both compartments – consisting of Field and Laboratory Emission Cells FLECs – are constantly flushed with air, one air stream containing a mixture of 20 VOCs, and concentrations in both compartments are measured after 1 h. Ten materials usually covering extensive surfaces indoors were consecutively exposed to the vapour mixture at concentration levels typically found in indoor environments. Under the chosen experimental conditions, five of these materials exhibited a permeability high enough that VOCs could be detected on the other side. Mass transport of VOCs into and through indoor materials has therefore been confirmed by experiment. The set-up allows for a quick screening of indoor materials with respect to their sorption capacity and permeability.

An extensive literature review of research on the impact of indoor air conditions; temperature, relative humidity and surface air velocity on materials emission rates is presented. This paper also presents the results of an experimental work to study the impact of room air temperature and relative humidity on materials emission rates. The results indicate that both the temperature and relative humidity have a significant effect on the emissions from paint and varnish. In the case of varnish, the results were consistent with earlier results. However, the paint results show inconsistent emission behaviour. Further, for both materials, the individual compounds did not necessarily follow the same trend established for the TVOC.

Cleaning is a large enterprise involving a large fraction of the workforce worldwide. A broad spectrum of cleaning agents has been developed to facilitate dust and dirt removal, for disinfection and surface maintenance. The cleaning agents are used in large quantities throughout the world. Although a complex pattern of exposure to cleaning agents and resulting health problems, such as allergies and asthma, are reported among cleaners, only a few surveys of this type of product have been performed. This paper gives a broad introduction to cleaning agents and the impact of cleaning on cleaners, occupants of indoor environments, and the quality of cleaning. Cleaning agents are usually grouped into different product categories according to their technical functions and the purpose of their use (e.g. disinfectants and surface care products). The paper also indicates the adverse health and comfort effects associated with the use of these agents in connection with the cleaning process. The paper identifies disinfectants as the most hazardous group of cleaning agents. Cleaning agents contain evaporative and non-evaporative substances. The major toxicologically significant constituents of the former are volatile organic compounds (VOCs), defined as substances with boiling points in the range of 0°C to about 400°C. Although laboratory emission testing has shown many VOCs with quite different time-concentration profiles, few field studies have been carried out measuring the exposure of cleaners. However, both field studies and emission testing indicate that the use of cleaning agents results in a temporal increase in the overall VOC level. This increase may occur during the cleaning process and thus it can enhance the probability of increased short-term exposure of the cleaners. However, the increased levels can also be present after the cleaning and result in an overall increased VOC level that can possibly affect the indoor air quality (IAQ) perceived by occupants. The variety and duration of the emissions depend inter alia on the use of fragrances and high boiling VOCs. Some building materials appear to increase their VOC emission through wet cleaning and thus may affect the IAQ. Particles and dirt contain a great variety of both volatile and non-volatile substances, including allergens. While the volatile fraction can consist of more than 200 different VOCs including formaldehyde, the non-volatile fraction can contain considerable amounts (>0.5%) of fatty acid salts and tensides (e.g. linear alkyl benzene sulphonates). The level of these substances can be high immediately after the cleaning process, but few studies have been conducted concerning this problem. The substances partly originate from the use of cleaning agents. Both types are suspected to be airway irritants. Cleaning activities generate dust, mostly by resuspension, but other occupant activities may also resuspend dust over longer periods of time. Personal sampling of VOCs and airborne dust gives higher results than stationary sampling. International bodies have proposed air sampling strategies. A variety of field sampling techniques for VOC and surface particle sampling is listed.

Building and furnishing materials and consumers products are important sources of formaldehyde and other volatile organic compounds (VOCs) in the indoor environment. The emission from materials is usually continuous and may last for many years in a building. The available evidence indicates that VOCs can cause adverse health effects to the building occupants and may contribute to symptoms of ‘Sick Building Syndrome’. Control of VOC emission should increasingly become an important consideration for the design and manufacture of polymeric materials used in buildings. The EC Construction Products Directive ‘Essential Requirements’ set a framework for limiting the use of materials that could pose a health risk to building occupants. Furthermore, the on-going development of voluntary labelling schemes and data bases of material emissions that could be used by building designers, should further strengthen the demand for ‘low VOC emitting’ products. This paper reviews available information about the emission of VOCs from polymeric building materials, the level of emissions in the indoor environment and the requirements for testing of the materials.

The emissions of two volatile organic compounds (VOCs) of concern from five building products (BPs) were measured in the field and laboratory emission cell (FLEC) up to 250d. The BPs (VOCs selected on the basis of abundance and low human odor thresholds) were: nylon carpet with latex backing (2-ethylhexanol, 4-phenylcyclohexene), PVC flooring (2-ethylhexanol, phenol), floor varnish on pretreated beechwood parquet (butyl acetate, N-methylpyrrolidone), sealant (hexane, dimethyloctanols), and waterborne wall paint on gypsum board (1,2-propandiol, Texanol). Ten different climate conditions were tested: four different air velocities from ca. 1cms-1 to ca. 9cms-1, three different temperatures (23, 35, and 60°C), two different relative humidities (0% and 50% RH), and pure nitrogen instead of clean air supply. Additionally, two sample specimen and two different batches were compared for repeatability and homogeneity. The VOCs were sampled on Tenax TA and determined by thermal desorption and gas chromatography (FID). Quantification was carried out by individual calibration of each VOC of concern. Concentration/time profiles of the selected VOCs (i.e. their concentration decay curves over time) in a standard room were used for comparison. Primary source emissions were not affected by the air velocity after a few days to any great extent. Both the temperature and relative humidity affected the emission rates, but depended strongly on the type of BP and type of VOC. Secondary (oxidative) source emissions were only observed for the PVC and for dimethyloctanols from the sealant. The time to reach a given concentration (emission rate) appears to be a good approach for future interlaboratory comparisons of BP’s VOC emissions.

Abstract The Field and Laboratory Emission Cell (FLEC) has been designed for VOC emission testing of material surfaces. Knowledge about the air flow field in the cell compartment is highly desired, as the air velocity at the sample surface may considerably influence the emission behaviour. A simple mathematical approach of flow theory predicted an unevenly distributed air flow into the FLEC. This could be confirmed by air velocity measurements using a self-constructed hot-wire anemometer. With a total flow of 250 ml min−1, air velocities measured at the surface ranged from ⩽ 0.1 to 0.9 cm s−1. A surface area of very low air velocities was detected in the FLEC centre with a radius of ≈20 mm. A VOC emission test using a simulated punctual source yielded different emission rates at different locations in the cell compartment.

Analyses of indoor air samples of semivolatile organic compounds (SVOCs) from five offices in two office buildings, a school classroom, and a room in a day-care center were generally strongly influenced by artifact formation. In the laboratory, the major artifacts could be produced by sampling mixtures of O3, NO2, and limonene in air on the sorbent, Tenax TA. Several SVOCs from O3 degradation of Tenax TA were detected, but only few were identified. The NO2 degradation of Tenax TA analyzed by thermal desorption and gas chromatography (TD-GC) almost exclusively formed 2,6-diphenyl-p-benzoquinone (DPQ) and 2,6-diphenyl-p-hydroquinone (DPHQ). The NO2/Tenax TA reaction could be calibrated, thus the NO2 concentration could be determined simultaneously with a SVOC measurement. However, the results indicated that DPQ may be reduced to DPHQ during TD-GC analysis by oxidation of other compounds adsorbed to Tenax TA. Sampling an air mixture of O3 in excess of limonene on Tenax TA followed by TD-GC analysis exclusively produced DPHQ. O3 alone produced neither DPQ nor DPHQ. It was found that reactive species (possibly Criegee biradicals and/or other organic radicals) from the O3/limonene :reaction were responsible for the production of DPHQ from Tenax TA. The results indicated that Tenax TA can be used as a trapping agent for some radicals by analysis of the DPQ/DPHQ formation. The present data were not sufficient to obtain evidence for degradation of Tenax TA by other radicals than NO and NO2 in indoor SVOC samples. However, the DPQ/DPHQ ratio indicated that DPHQ has been formed from DPQ by oxidation of other adsorbed compounds in some of the samples.

Reactions among indoor pollutants can produce products that, otherwise, might not be present in an indoor environment. To be relevant in an indoor setting, a chemical reaction must occur within a time interval shorter than or comparable to the residence time for a packet of indoor air. At typical air exchange rates, the reactions that meet this criterion include those of ozone with nitric oxide, nitrogen dioxide, and selected unsaturated hydrocarbons; thermal decomposition of peroxyacyl nitrates; numerous free radical reactions; and selected heterogeneous processes. Stable products include aldehydes, ketones, carboxylic acids and various organic nitrates. These reactions also generate free radicals, starting with the nitrate radical, Criegree biradicals, and peroxyacyl radicals, and leading to the hydroxyl, alkyl, alkylperoxy, hydroperoxy, and alkoxy radicals. Such radicals can react with other indoor species yielding additional aldehydes, ketones, carboxylic acids, dinitrates and peroxyacyl nitrates. Some of the potential products are known or suspected to be irritating (e.g. methacrolein, nonanoic acid, 1,2-propanediol dinitrate, peroxybenzoyl nitrate, and radical anions of the type [Cl… NO2]−) However, some of these same products are difficult to detect using the sampling and analysis techniques currently applied to indoor air.

A foundational journal article describing the Field and Laboratory Emission Cell (FLEC) for measuring VOC emissions from indoor building materials.

The paper evaluates how relative humidity affects FLEC measurements of VOC emissions from latex paint on gypsum board and compares the results with small test chambers.

A peer-reviewed ASTM chapter comparing the performance of the Field and Laboratory Emission Cell (FLEC) with conventional emissions-testing chambers.

A labeling system for building materials' primary emission of volatile organic compounds (VOCs) according to their impact on comfort and health has been developed and introduced in Denmark. The system unifies chemical emission testing over time (months), modeling (including a standard room and mathematical modeling of the emission profile, when necessary), and health evaluation. As a first step, the Danish system focuses on comfort, i.e. odor annoyance and mucous membrane irritation, because of their preponderance in the sick building syndrome reporting and the absence of other relevant data on indoor air related health effects. Two design criteria have been set: the labeling system shall be easily comprehensible and at the same time operational and dynamic. The principle is to determine the time value, t(Cm), required to reach the relevant indoor air value, Cm (presently, based on odor and mucous membrane irritation thresholds), in a standard room. Odor thresholds are used because they generally are at least one order of magnitude lower than mucous membrane irritation thresholds. t(Cm) is a measure of the period of time during which a new building material may cause indoor air quality problems, unless special precautions are made. The system may also be used for singular VOCs of which a specific health endpoint has been reported. The Danish labeling system is illustrated with the emission testing and comfort evaluation of two sealants using the Field and Laboratory Emission Cell (FLEC)

The paper evaluates FLEC performance, compares emission results with a small climate chamber and demonstrates field application in an office with malodorous, moisture-damaged linoleum.

A conference paper evaluating the usefulness of FLEC for measuring emissions from engineered wood products.

The original Healthy Buildings contribution introducing the Field and Laboratory Emission Cell (FLEC).