The FLEC® has been validated and used in research for many years.
Below is a publication list of journal articles, abstracts, poster or oral presentations where the FLEC or CHEMATEC’s other products have been in focus.
If you have anything that can be added to the list, we encourage you to contact CHEMATEC.
Wei, Wenjuan; Mandin, Corinne; Ramalho, Olivier
In: Chemosphere, vol. 195, pp. 223 - 235, 2018, ISSN: 0045-6535.
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.
Kashyap, Durba; Agarwal, Tripti
In: Science of The Total Environment, vol. 635, pp. 817 - 827, 2018, ISSN: 0048-9697.
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.
Thevenet, F; Debono, O; Rizk, M; Caron, F; Verriele, M; Locoge, N
In: Building and Environment, vol. 137, pp. 138 - 146, 2018, ISSN: 0360-1323.
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.
In: Data in Brief, 2018, ISSN: 2352-3409.
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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.
Mao, Yun-Feng; Li, Zhuo; Mu, Yu-Tong; He, Ya-Ling; Tao, Wen-Quan
In: Building and Environment, vol. 128, pp. 180 - 189, 2018, ISSN: 0360-1323.
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.
Pei, Jingjing; Yin, Yihui; Cao, Jianping; Sun, Yahong; Liu, Junjie; Zhang, Yinping
In: Building and Environment, vol. 125, pp. 339 - 347, 2017, ISSN: 0360-1323.
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.
In: TrAC Trends in Analytical Chemistry, vol. 97, pp. 297 - 308, 2017, ISSN: 0165-9936.
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.
Cui, X; Mohan, B; Islam, M R; Chou, S K; Chua, K J
In: Energy Procedia, vol. 142, pp. 1874 - 1879, 2017, ISSN: 1876-6102, (Proceedings of the 9th International Conference on Applied Energy).
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.
Knudsen, Sofie M; Gunnarsen, Lars; Madsen, Anne Mette
In: Building and Environment, vol. 125, pp. 475 - 483, 2017, ISSN: 0360-1323.
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.
Knudsen, Sofie M; Gunnarsen, Lars; Madsen, Anne Mette
In: Building and Environment, vol. 122, pp. 161 - 170, 2017, ISSN: 0360-1323.
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.
Cui, X; Mohan, B; Islam, M R; Chou, S K; Chua, K J
In: Energy Procedia, vol. 143, pp. 283 - 288, 2017, ISSN: 1876-6102, (Leveraging Energy Technologies and Policy Options for Low Carbon Cities).
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.
Bardage, S L
6 - Performance of buildings Incollection
In: Jones, Dennis; Brischke, Christian (Ed.): Performance of Bio-based Building Materials, pp. 335 - 383, Woodhead Publishing, 2017, ISBN: 978-0-08-100982-6.
The chapter deals with different aspects on the use and performance of bio-based building materials in constructions and buildings.
Rizk, Malak; Verriele, Marie; Mendez, Maxence; Blond, Nadège; Dusanter, Sébastien; Schoemaecker, Coralie; Blondeau, Patrice; Calvé, Stéphane Le; Locoge, Nadine
In: Building and Environment, vol. 99, pp. 239 - 251, 2016, ISSN: 0360-1323.
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.
Mao, Yun-Feng; Li, Zhuo; He, Ya-Ling; Tao, Wen-Quan
CFD analysis of SVOC mass transfer in different chambers Journal Article
In: International Journal of Heat and Mass Transfer, vol. 99, pp. 613 - 621, 2016, ISSN: 0017-9310.
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.
Wu, Yaoxing; Cox, Steven S; Xu, Ying; Liang, Yirui; Won, Doyun; Liu, Xiaoyu; Clausen, Per A; Rosell, Lars; Benning, Jennifer L; Zhang, Yinping; Little, John C
In: Building and Environment, vol. 95, pp. 126 - 132, 2016, ISSN: 0360-1323.
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.
Harb, P; Sivachandiran, L; Gaudion, V; Thevenet, F; Locoge, N
In: Chemical Engineering Journal, vol. 306, pp. 568 - 578, 2016, ISSN: 1385-8947.
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.
Lyng, Nadja Lynge; Gunnarsen, Lars; Andersen, Helle Vibeke; Kofoed-Sørensen, Vivi; Clausen, Per Axel
In: Building and Environment, vol. 101, pp. 77 - 84, 2016, ISSN: 0360-1323.
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.
Rizk, M; Verriele, M; Dusanter, S; Schoemaecker, C; calve, Le S; Locoge, N
In: Building and Environment, vol. 99, pp. 200 - 209, 2016, ISSN: 0360-1323.
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.
Jeon, Seunghwan; Kim, Ki-Tae; Choi, Kyungho
In: Science of The Total Environment, vol. 547, pp. 441 - 446, 2016, ISSN: 0048-9697.
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.
Xiong, Jianyin; Cao, Jianping; Zhang, Yinping
In: Building and Environment, vol. 95, pp. 314 - 321, 2016, ISSN: 0360-1323.
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.
Noguchi, Miyuki; Yamasaki, Akihiro
In: Building and Environment, vol. 100, pp. 197 - 202, 2016, ISSN: 0360-1323.
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.
Liu, Cong; Zhang, Yinping
In: Building and Environment, vol. 95, pp. 283 - 290, 2016, ISSN: 0360-1323.
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.
Kalimeri, Krystallia K; Saraga, Dikaia E; Lazaridis, Vasileios D; Legkas, Nikolaos A; Missia, Dafni A; Tolis, Evangelos I; Bartzis, John G
In: Atmospheric Pollution Research, vol. 7, no. 6, pp. 1128 - 1142, 2016, ISSN: 1309-1042.
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.
Rizk, M; Verriele, M; Dusanter, S; Schoemaecker, C; Calve, Le S; Locoge, N
In: Data in Brief, vol. 6, pp. 953 - 958, 2016, ISSN: 2352-3409.
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A Proton Transfer Reaction-Mass Spectrometer (PTR-MS) has been coupled to the outlet of a Field and Laboratory Emission Cell (FLEC), to measure volatile organic compounds (VOC) concentration during a sorption experiments (Rizk et al., this issue) . The limits of detection of the PTR-MS for three VOCs are presented for different time resolution (2, 10 and 20s). The mass transfer coefficient was calculated in the FLEC cavity for the different flow rates. The concentration profile obtained from a sorption experiment performed on a gypsum board and a vinyl flooring are also presented in comparison with the profile obtained for a Pyrex glass used as a material that do not present any sorption behavior (no sink). Finally, the correlation between the concentration of VOCs adsorbed on the surface of the gypsum board at equilibrium (Cse) and the concentration of VOCs Ce measured in the gas phase at equilibrium is presented for benzene, C8 aromatics and toluene.
Liu, Xiaoyu; Allen, Matthew R; Roache, Nancy F
In: Atmospheric Environment, vol. 140, pp. 333 - 341, 2016, ISSN: 1352-2310.
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.
Liu, Xiaoyu; Guo, Zhishi; Krebs, Kenneth A; Greenwell, Dale J; Roache, Nancy F; Stinson, Rayford A; Nardin, Joshua A; Pope, Robert H
In: Chemosphere, vol. 149, pp. 62 - 69, 2016, ISSN: 0045-6535.
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.
Li, Zhen-Xing; Zhong, Ting-Shu; Niu, Jian-Lei; Xiao, Fu; Zhang, Li-Zhi
In: International Journal of Heat and Mass Transfer, vol. 84, pp. 390 - 400, 2015, ISSN: 0017-9310.
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°.
Liang, Yirui; Caillot, Olivier; Zhang, Jianshun; Zhu, Jiping; Xu, Ying
In: Building and Environment, vol. 89, pp. 141 - 149, 2015, ISSN: 0360-1323.
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.
Liang, Yirui; Xu, Ying
In: Atmospheric Environment, vol. 103, pp. 147 - 155, 2015, ISSN: 1352-2310.
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.
Poulhet, Guillaume; Dusanter, Sébastien; Crunaire, Sabine; Locoge, Nadine; Kaluzny, Pascal; Coddeville, Patrice
In: Building and Environment, vol. 93, pp. 106 - 114, 2015, ISSN: 0360-1323, (Special Issue: Indoor pollutants, chemistry and health- Selected papers presented at Indoor Air 2014 conference in Hong Kong).
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.
Tang, S W; Chen, E; Li, Z J; Shao, H Y
In: Building and Environment, vol. 84, pp. 221 - 227, 2015, ISSN: 0360-1323.
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.
Chen, Qun; Hu, Kang
In: Atmospheric Environment, vol. 96, pp. 61 - 69, 2014, ISSN: 1352-2310.
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.
Vibenholt, Anni; Clausen, Per Axel; Wolkoff, Peder
In: Chemosphere, vol. 107, pp. 230 - 239, 2014, ISSN: 0045-6535.
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.
Schripp, Tobias; Salthammer, Tunga; Fauck, Christian; Bekö, Gabriel; Weschler, Charles J
In: Science of The Total Environment, vol. 494-495, pp. 299 - 305, 2014, ISSN: 0048-9697.
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.
Marć, Mariusz; Namieśnik, Jacek; Zabiegała, Bożena
In: Science of The Total Environment, vol. 481, pp. 35 - 46, 2014, ISSN: 0048-9697.
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.
Rauert, Cassandra; Lazarov, Borislav; Harrad, Stuart; Covaci, Adrian; Stranger, Marianne
In: Atmospheric Environment, vol. 82, pp. 44 - 55, 2014, ISSN: 1352-2310.
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.
Poulhet, G; Dusanter, S; Crunaire, S; Locoge, N; Gaudion, V; Merlen, C; Kaluzny, P; Coddeville, P
In: Building and Environment, vol. 71, pp. 111 - 120, 2014, ISSN: 0360-1323.
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.
Madsen, Anne Mette; Tendal, Kira; Frederiksen, Margit W
In: Science of The Total Environment, vol. 468-469, pp. 1112 - 1121, 2014, ISSN: 0048-9697.
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.
Xiong, Jianyin; Wang, Lixin; Bai, Yuhua; Zhang, Yinping
In: Building and Environment, vol. 66, pp. 65 - 71, 2013, ISSN: 0360-1323.
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.
Zhang, Li-Zhi; Li, Zhen-Xing
In: Journal of Membrane Science, vol. 434, pp. 65 - 73, 2013, ISSN: 0376-7388.
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.
Guo, Min; Pei, Xiaoqiang; Mo, Feifei; Liu, Jianlei; Shen, Xueyou
In: Journal of Environmental Sciences, vol. 25, no. 5, pp. 908 - 915, 2013, ISSN: 1001-0742.
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.
Liang, Weihui; Yang, Xudong
In: Building and Environment, vol. 69, pp. 114 - 120, 2013, ISSN: 0360-1323.
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.
Zhang, Li-Zhi (Ed.)
In: Zhang, Li-Zhi (Ed.): Conjugate Heat and Mass Transfer in Heat Mass Exchanger Ducts, pp. 371 - 376, Academic Press, Boston, 2013, ISBN: 978-0-12-407782-9.
Hu, Kang; Chen, Qun; Hao, Jun-Hong
In: Atmospheric Environment, vol. 79, pp. 695 - 704, 2013, ISSN: 1352-2310.
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.
Harvey, Scott D; Wahl, Jon H
In: Journal of Chromatography A, vol. 1256, pp. 58 - 66, 2012, ISSN: 0021-9673.
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.
Liu, Z; Little, J C
In: Pacheco-Torgal, F; Jalali, S; Fucic, A (Ed.): Toxicity of Building Materials, pp. 122 - 137, Woodhead Publishing, 2012, ISBN: 978-0-85709-122-2.
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.
Marć, Mariusz; Zabiegała, Bożena; Namieśnik, Jacek
In: TrAC Trends in Analytical Chemistry, vol. 32, pp. 76 - 86, 2012, ISSN: 0165-9936.
Tags: Air quality, Building material, Direct thermal desorption, emission rate, Emission test chamber, Field and laboratory emission cell, Indoor air, Passive flux sampler, Sampling device, Volatile organic compound| | |
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.
Schripp, Tobias; Langer, Sarka; Salthammer, Tunga
In: Atmospheric Environment, vol. 54, pp. 365 - 372, 2012, ISSN: 1352-2310.
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.
Liu, Z; Little, J C
In: Pacheco-Torgal, F; Jalali, S; Fucic, A (Ed.): Toxicity of Building Materials, pp. 76 - 121, Woodhead Publishing, 2012, ISBN: 978-0-85709-122-2.
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.
Salem, Mohamed Z M; Böhm, Martin; Srba, Jaromír; Beránková, Jitka
In: Building and Environment, vol. 49, pp. 86 - 96, 2012, ISSN: 0360-1323.
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.