Temporal trends of decabromodiphenyl ether and emerging brominated flame retardants in dust,air and window surfaces of newly built low‐energy preschools

The envelope of low‐energy buildings is generally constructed with significant amounts of plastics, sealants and insulation materials that are known to contain various chemical additives to improve specific functionalities. A commonly used group of additives are flame retardants to prevent the spread of fire. In this study, decabromodiphenyl ether (BDE‐209) and fourteen emerging brominated flame retardants (BFRs) were analyzed in indoor dust, air and on the window surface of newly built low‐energy preschools to study their occurrence and distribution. BDE‐209 and decabromodiphenyl ethane (DBDPE) were frequently detected in the indoor dust (BDE‐209: <4.1‐1200 ng/g, DBDPE: <2.2‐420 ng/g) and on window surfaces (BDE‐209: <1000‐20 000 pg/m², DBDPE: <34‐5900 pg/m²) while the other thirteen BFRs were found in low levels (dust: <0.0020‐5.2 ng/g, window surface: 0.0078‐35 pg/m²). In addition, the detection frequencies of BFRs in the indoor air were low in all preschools. Interestingly, the dust levels of BDE‐209 and DBDPE were found to be lower in the environmentally certified low‐energy preschools, which could be attributed to stricter requirements on the chemical content in building materials and products. However, an increase of some BFR levels in dust was observed which could imply continuous emissions or introduction of new sources.     

Occurrence and human exposure assessment of organophosphate flame retardants in indoor dust from various microenvironments of the Rhine/Main region,Germany

We analyzed organophosphate flame retardants (OPFRs) in 74 indoor dust samples collected from seven microenvironments (building material markets, private cars, daycare centers, private homes, floor/carpet stores, offices, and schools) in the Rhine/Main region of Germany. Ten of 11 target OPFRs were ubiquitously detected, some with more than 97% detection frequency, including tris(1,3‐dichloroisopropyl)phosphate (TCIPP), tris(2‐butoxyethyl)phosphate (TBOEP), triphenyl phosphate (TPHP), and tris(isobutyl) phosphate (TIBP). Total concentrations (∑OPFRs) ranged from 5.9 to 4800 μg/g, with TBOEP and TCIPP being the most abundant congeners. The ∑OPFRs in schools, private cars, offices, and daycare centers were significantly (P<.05) higher than in private homes. The ∑OPFRs for building material markets (19 μg/g) and floor/carpet stores (20 μg/g) showed no significant difference to the other microenvironments, likely because of forced ventilation. The profiles of OPFRs in dust samples from offices and private homes were highly similar, while profiles from the other five microenvironments were substantially different. Comparison of our results with previous studies indicates a significant global variation in OPFR concentrations and their profiles, reflecting distinct fire safety regulations in different countries and/or different sampling strategies. Dust ingestion constitutes the major exposure pathway to OPFRs for toddlers, while air inhalation is the major pathway for adults.     

Assessment of human exposure to indoor organic contaminants via dust ingestion in Pakistan

Ingestion of indoor dust has been acknowledged as an important route of exposure to organic contaminants (OCs). We investigated the presence of polybrominated diphenyl ethers (PBDEs), novel brominated flame retardants (NBFRs), organophosphate flame retardants (OPFRs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) in indoor floor dust from rural homes (N=31) and mosques (N=12) in Gujrat, Pakistan. Low concentrations were observed for most contaminants. OPFRs were the principle contaminants, with tri-(2-butoxyethyl)-phosphate (TBEP) and tri-phenyl-phosphate (TPP) having medians of 66 and 109 ng/g, respectively. PBDEs were only minor constituents in the investigated samples, with BDE 209 (median 40 ng/g) being the most important congener. Levels and profile of ∑PBDEs, ∑NBFRs, ∑HCHs, ∑DDTs, and ∑PCBs revealed no difference (P<0.05) between samples of dust from homes and mosques, indicating similar emission sources. Exposure scenarios using 5th percentile, median, mean, and 95th percentile levels were estimated for both adult and toddlers. Typical high-end, using median levels and high dust ingestion, exposure for adults were 0.02, 0.02, 0.03, <0.01, and 0.65 ng/kg bw/day and for toddlers 0.39, 0.45, 0.69, 0.01, and 15.2 ng/kg bw/day for ∑PBDEs, ∑NBFRs, ∑OCPs, ∑PCBs, and ∑OPFRs, respectively. To the authors' knowledge, this is the first study to document the presence of indoor OCs in Pakistani dust. PRACTICAL IMPLICATIONS: This is the first report on the analysis of various contaminants in indoor dust from Pakistan. Some of these chemicals are currently being used in different consumer products. The study will help to further an understanding of the levels of different organic contaminants (OCs) in Pakistani indoor environments and will enlighten the generally ignored area of environmental pollution in Pakistan. Furthermore, studies based on animal models have shown that some of the analyzed chemicals can cause different types of chronic toxicities. However, our results showed that the levels of estimated exposure via dust ingestion for all chemicals were several orders of magnitude lower than their reference dose (RfD) values or than those reported in studies from Belgium, China, Singapore, and the UK (Ali et al., 2011a; Harrad et al., 2008; Tan et al., 2007a,b; Van den Eede et al., 2011a; Wang et al., 2010).     

Test chamber investigation of the volatilization from source materials of brominated flame retardants and their subsequent deposition to indoor dust

Numerous studies have reported elevated concentrations of brominated flame retardants (BFRs) in dust from indoor micro‐environments. Limited information is available, however, on the pathways via which BFRs in source materials transfer to indoor dust. The most likely hypothesized pathways are (a) volatilization from the source with subsequent partitioning to dust, (b) abrasion of the treated product, transferring microscopic fibers or particles to the dust (c) direct uptake to dust via contact between source and dust. This study reports the development and application of an in‐house test chamber for investigating BFR volatilization from source materials and subsequent partitioning to dust. The performance of the chamber was evaluated against that of a commercially available chamber, and inherent issues with such chambers were investigated, such as loss due to sorption of BFRs to chamber surfaces (so‐called sink effects). The partitioning of polybrominated diphenyl ethers to dust, post‐volatilization from an artificial source was demonstrated, while analysis in the test chamber of a fabric curtain treated with the hexabromocyclododecane formulation, resulted in dust concentrations exceeding substantially those detected in the dust pre‐experiment. These results provide the first experimental evidence of BFR volatilization followed by deposition to dust.     

Exposure to organophosphate and polybrominated diphenyl ether flame retardants via indoor dust and childhood asthma

Although the ubiquitous detection of polybrominated diphenyl ether (PBDE) and organophosphate flame retardants (PFRs) in indoor dust has raised health concerns, only very few epidemiological studies have assessed their impact on human health. Inhalation of dust is one of the exposure routes of FRs, especially in children and can be hazardous for the respiratory health. Moreover, PFRs are structurally similar to organophosphate pesticides, which have been associated with allergic asthma. Thus, we investigated whether the concentrations of PFRs and PBDEs in indoor dust are associated with the development of childhood asthma. We selected 110 children who developed asthma at 4 or at 8 years old and 110 matched controls from a large prospective birth cohort (BAMSE – Barn, Allergy, Milieu Stockholm Epidemiology). We analyzed the concentrations of 7 PFRs and 21 PBDEs in dust collected around 2 months after birth from the mother's mattress. The abundance rank in dust was as follows: TBOEP?TPHP>mmp‐TMPP>EHDPHP~TDCIPP>TCEP~TCIPP~BDE‐209?BDE‐99>BDE‐47>BDE‐153>BDE‐183>BDE‐100. There was no positive association between the FRs in mattress dust and the development of childhood asthma. In contrast, dust collected from mattresses of the mothers of children who would develop asthma contained significant lower levels of TPHP and mmp‐TMPP. This study provides data on a wide range of PFRs and PBDEs in dust samples and development of asthma in children.     

Phosphorus flame retardants in indoor dust and their relation to asthma and allergies of inhabitants

Organophosphate esters are used as additives in flame retardants and plasticizers, and they are ubiquitous in the indoor environment. Phosphorus flame retardants (PFRs) are present in residential dust, but few epidemiological studies have assessed their impact on human health. We measured the levels of 11 PFRs in indoor floor dust and multi‐surface dust in 182 single‐family dwellings in Japan. We evaluated their correlations with asthma and allergies of the inhabitants. Tris(2‐butoxyethyl) phosphate was detected in all samples (median value: 580 μg/g in floor dust, 111 μg/g in multi‐surface dust). Tris(2‐chloro‐iso‐propyl) phosphate (TCIPP) was detected at 8.69 μg/g in floor dust and 25.8 μg/g in multi‐surface dust. After adjustment for potential confounders, significant associations were found between the prevalence of atopic dermatitis and the presence of TCIPP and tris(1,3‐dichloro‐2‐propyl) phosphate in floor dust [per log₁₀‐unit, odds ratio (OR): 2.43 and 1.84, respectively]. Tributyl phosphate was significantly associated with the prevalence of asthma (OR: 2.85 in floor dust, 5.34 in multi‐surface dust) and allergic rhinitis (OR: 2.55 in multi‐surface dust). PFR levels in Japan were high compared with values reported previously for Europe, Asia‐Pacific, and the USA. Higher levels of PFRs in house dust were related to the inhabitants' health status.     

Determining source strength of semivolatile organic compounds using measured concentrations in indoor dust

Consumer products and building materials emit a number of semivolatile organic compounds (SVOCs) in the indoor environment. Because indoor SVOCs accumulate in dust, we explore the use of dust to determine source strength and report here on analysis of dust samples collected in 30 US homes for six phthalates, four personal care product ingredients, and five flame retardants. We then use a fugacity‐based indoor mass balance model to estimate the whole‐house emission rates of SVOCs that would account for the measured dust concentrations. Di‐2‐ethylhexyl phthalate (DEHP) and di‐iso‐nonyl phthalate (DiNP) were the most abundant compounds in these dust samples. On the other hand, the estimated emission rate of diethyl phthalate is the largest among phthalates, although its dust concentration is over two orders of magnitude smaller than DEHP and DiNP. The magnitude of the estimated emission rate that corresponds to the measured dust concentration is found to be inversely correlated with the vapor pressure of the compound, indicating that dust concentrations alone cannot be used to determine which compounds have the greatest emission rates. The combined dust‐assay modeling approach shows promise for estimating indoor emission rates for SVOCs.     

Flame retardants in the indoor environment -- Part II: release of VOCs (triethylphosphate and halogenated degradation products) from polyurethane

Organophosphate esters, halogenated and non-halogenated, are frequently used for fire protection of building materials. With regard to toxicological profiles it is desired to avoid human exposure in the indoor environment. Moreover, some hazardous volatile organic compounds detected in indoor air are directly linked to the utilization of flame retardants. In this study, different polyurethane (PUR) products for building and indoor use treated with organophosphate flame retardants were tested in 1 m(3) emission test chambers. Emissions of flame retardants and degradation products were measured under living conditions. A PUR hard foam sample showed area-specific emission rates >100 microg/m(2) h for the compound triethylphosphate. During the tests several chlorinated degradation products of organophophorous flame retardants could be identified in the chamber air.     

Formaldehyde and acetaldehyde exposure mitigation in US residences: in‐home measurements of ventilation control and source control

Measurements were taken in new US residences to assess the extent to which ventilation and source control can mitigate formaldehyde exposure. Increasing ventilation consistently lowered indoor formaldehyde concentrations. However, at a reference air exchange rate of 0.35 h^?1, increasing ventilation was up to 60% less effective than would be predicted if the emission rate were constant. This is consistent with formaldehyde emission rates decreasing as air concentrations increase, as observed in chamber studies. In contrast, measurements suggest acetaldehyde emission was independent of ventilation rate. To evaluate the effectiveness of source control, formaldehyde concentrations were measured in Leadership in Energy and Environmental Design (LEED)‐certified/Indoor airPLUS homes constructed with materials certified to have low emission rates of volatile organic compounds (VOC). At a reference air exchange rate of 0.35 h^?1, and adjusting for home age, temperature and relative humidity, formaldehyde concentrations in homes built with low‐VOC materials were 42% lower on average than in reference new homes with conventional building materials. Without adjustment, concentrations were 27% lower in the low‐VOC homes. The mean and standard deviation of formaldehyde concentration was 33 μg/m³ and 22 μg/m³ for low‐VOC homes and 45 μg/m³ and 30 μg/m³ for conventional.     

Chlorinated ethyl and isopropyl phosphoric acid triesters in the indoor environment--an inter-laboratory exposure study

The chlorinated organo-phosphate triesters, tris(2-chloroethyl)-phosphate (TCEP) and tris(monochloroisopropyl)-phosphate (TCPP), are employed in consumer articles for indoor usage, e.g. flame retardants and plasticizers in foam material as well as in paints, varnishes and wallpapers. As a result of this widespread usage, employing domestic dust as a matrix, both chemicals have been detected in the indoor environment. TCEP was present in 85% of a total of 983 samples, whereas TCPP was found in 60-90% of 436 cases (with levels ranging from 0.1 to 375 mg/kg). Since TCEP and TCPP residues in domestic dust are assumed to be condensates arising from primary sources, spot check analysis of various indoor materials was performed. The results show that soft foams, paints and wallpapers contained mainly TCEP, whereas in insulation and sealant foams high levels of TCPP were found. Moreover, TCEP can also be detected in indoor air in concentrations up to 6,000 ng/m3. On the basis of this data, we estimated the levels of indoor exposure via oral and inhalative ingestion.     

Indoor organophosphate and polybrominated flame retardants in Tokyo

In Japan, organophosphate and polybrominated flame retardants are used in building materials and electric appliances to protect them from fire hazards. In this study, to identify the emission sources of these flame retardants to indoor air, the migration rates (flux) of organophosphate and polybrominated flame retardants from building materials and electrical appliances to solid extraction disks that were placed in contact with the interior surfaces were measured. In addition to the migration test, indoor air and outdoor air concentrations of these flame retardants were investigated. With regard to building materials in a newly built house, triethylphosphate (TEP) and tributylphosphate (TBP) were detected in the wall and ceiling coverings, and tris(2-butoxyethyl)phosphate (TBEP) was detected in the wooden flooring cleaned with a floor polish agent. With regard to electrical appliances, triphenylphosphate (TPHP) was predominantly detected in computer monitors and tris(2-chloroethyl) phosphate (TCEP) in television (TV) sets, with the highest median levels. Among the polybrominated compounds, only 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) was detected from a few old TV sets manufactured before 1995. In an indoor and outdoor air survey, nine organophosphates and nine polybrominated flame retardants were detected from indoor air. In outdoor air, only four organophosphate flame retardants were detected. The maximum level of indoor organophosphate compounds was 1260 ng/m(3) with tris(2-chloro-1-methylethyl) phosphate (TCPP), and that of polybrominated compounds was 29.5 ng/m(3) with hexabromocyclododecane (HBCD). Tetrabromobisphenol A (TBBPA) was not detected in this study, although it has the largest demand among flame retardants in Japan. The results of the migration test and the indoor air survey revealed that in indoor air, organophosphate compounds were more predominant than polybrominated compounds in Tokyo. PRACTICAL IMPLICATIONS: Polybrominated biphenyls (PBB) and polybrominated diphenyl ethers (PBDE) are commonly used as flame retardants in plastics. The use of these two compounds in electric appliances will be banned in 2007 by the EU Directives on waste electrical and electronic equipment (WEEE) and on the restriction of the use of certain hazardous substances (RoHS) in electrical and electronic equipment. In Japan, the use of PBB was banned and that of PBDE diminished in the early 1990s by the self-imposed controls of the Japanese Flame Retardants Conference (Akutu and Hori, 2004). In Japan, the predominantly used organic flame retardants were tetrabromobisphenol A and organophosphate compounds. Tetrabromobisphenol A has been reported to disrupt endocrine systems (Kitamura et al., 2005), and some organophosphate flame retardants were recently reported to have neurochemical hazardous effects. Furthermore, organophosphate compounds were suspected to cause endocrine-disrupting effects (Fang et al., 2003; Ohyama et al., 2005) or attention deficit hyperactivity disorder (ADHD) (Winrow et al., 2003). In this study, organophosphate and polybrominated flame retardants were surveyed in indoor environments in Tokyo.     

A comparative study of walking‐induced dust resuspension using a consistent test mechanism

Human walking influences indoor air quality mainly by resuspending dust particles settled on the floor. This study characterized walking‐induced particle resuspension as a function of flooring type, relative humidity (RH), surface dust loading, and particle size using a consistent resuspension mechanism. Five types of flooring, including hardwood, vinyl, high‐density cut pile carpet, low‐density cut pile carpet, and high‐density loop carpet, were tested with two levels of RH (40% and 70%) and surface dust loading (2 and 8 g/m²), respectively. Resuspension fraction r_a (fraction of surface dust resuspended per step) for house dust was found to be varied from 10^?7 to 10^?4 (particle size: 0.4–10 µm). Results showed that for particles at 0.4–3.0 µm, the difference in resuspension fraction between carpets and hard floorings was not significant. For particles at 3.0–10.0 µm, carpets exhibited higher resuspension fractions compared with hard floorings. Increased RH level enhanced resuspension on high‐density cut pile carpet, whereas the opposite effect was observed on hard floorings. Higher surface dust loading was associated with lower resuspension fractions on carpets, while on hard floorings the effect of surface dust loading varied with different RH levels.     

From air to clothing: characterizing the accumulation of semi‐volatile organic compounds to fabrics in indoor environments

Uptake kinetics of semi‐volatile organic compounds (SVOCs) present indoors, namely phthalates and halogenated flame retardants (HFRs), were characterized for cellulose‐based cotton and rayon fabrics. Cotton and rayon showed similar accumulation of gas‐ and particle‐phase SVOCs, when normalized to planar surface area. Accumulation was 3–10 times greater by rayon than cotton, when normalized to Brunauer–Emmett–Teller (BET) specific surface area which suggests that cotton could have a longer linear uptake phase than rayon. Linear uptake rates of eight consistently detected HFRs over 56 days of 0.35–0.92 m³/day.dm² planar surface area and mass transfer coefficients of 1.5–3.8 m/h were statistically similar for cotton and rayon and similar to those for uptake to passive air sampling media. These results suggest air‐side controlled uptake and that, on average, 2 m² of clothing typically worn by a person would sequester the equivalent of the chemical content in 100 m³ of air per day. Distribution coefficients between fabric and air (K′) ranged from 6.5 to 7.7 (log K′) and were within the range of partition coefficients measured for selected phthalates as reported in the literature. The distribution coefficients were similar for low molecular weight HFRs, and up to two orders of magnitude lower than the equilibrium partition coefficients estimated using the COSMO‐RS model. Based on the COSMO‐RS model, time to reach 95% of equilibrium for PBDEs between fabric and gas‐phase compounds ranged from 0.1 to >10 years for low to high molecular weight HFRs.     

Secondary organic aerosol formation initiated by α‐terpineol ozonolysis in indoor air

Secondary organic aerosol (SOA) owing to reactive organic gas (ROG) ozonolysis can be an important indoor particle source. However, SOA formation owing to ozonolysis of α‐terpineol, which is emitted by consumer product usage and reacts strongly with ozone, has not been systematically quantified. Therefore, we conducted 21 experiments to investigate the SOA formation initiated by α‐terpineol ozonolysis for high (0.84 h^?1), moderate (0.61 h^?1), and low (0.36 h^?1) air exchange rates (AER), which is the frequency with which indoor is replaced by outdoor air. α‐Terpineol concentrations of 6.39 to 226 ppb were combined with high ozone (~25 ppm) to ensure rapid and complete ozonolysis. No reactants were replenished, so SOA peaked quickly and then decreased due to AER and surface losses, and peak SOA ranged from 2.03 to 281 μg/m³ at unit density. SOA mass formation was parameterized with the aerosol mass fraction (AMF), a.k.a. the SOA yield, and AMFs ranged from 0.056 to 0.24. The AMFs strongly and positively correlated with reacted α‐terpineol, whereas they weakly and negatively correlated with higher AERs. One‐product, two‐product, and volatility basis set (VBS) models were fit to the AMF data. Predictive modeling demonstrated that α‐terpineol ozonolysis could meaningfully form SOA in indoor air.     

Chemical exposures from upholstered furniture with various flame retardant technologies

Upholstered furniture is often manufactured with polyurethane foam (PUF) containing flame retardants (FRs) to prevent the risk of a fire and/or to meet flammability regulations, however, exposure to certain FRs and other chemicals have been linked to adverse health effects. This study developed a new methodology for evaluating volatile organic compound (VOC) and FR exposures to users of upholstered furniture by simulating use of a chair in a controlled exposure chamber and assessing the health significance of measured chemical exposure. Chairs with different fire-resistant technologies were evaluated for VOC and FR exposures via inhalation, ingestion, and dermal contact exposure routes. Data show that VOC exposure levels are lower than threshold levels defined by the US and global indoor air criteria. Brominated FRs were not detected from the studied chairs. The organophosphate FRs added to PUF were released into the surrounding air (0.4 ng/m³) and as dust (16 ng/m²). Exposure modeling showed that adults are exposed to FRs released from upholstered furniture mostly by dermal contact and children are exposed via dermal and ingestion exposure. Children are most susceptible to FR exposure/dose (2 times higher average daily dose than adults) due to their frequent hand to mouth contact.     

A general mechanistic model for predicting the fate and transport of phthalates in indoor environments

A mechanistic model that considers particle dynamics and their effects on surface emissions and sorptions was developed to predict the fate and transport of phthalates in indoor environments. A controlled case study was conducted in a test house to evaluate the model. The model‐predicted evolving concentrations of benzyl butyl phthalate in indoor air and settled dust and on interior surfaces are in good agreement with measurements. Sensitivity analysis was performed to quantify the effects of parameter uncertainties on model predictions. The model was then applied to a typical residential environment to investigate the fate of di‐2‐ethylhexyl phthalate (DEHP) and the factors that affect its transport. The predicted steady‐state DEHP concentrations were 0.14 μg/m³ in indoor air and ranged from 80 to 46 000 μg/g in settled dust on various surfaces, which are generally consistent with the measurements of previous studies in homes in different countries. An increase in the mass concentration of indoor particles may significantly enhance DEHP emission and its concentrations in air and on surfaces, whereas increasing ventilation has only a limited effect in reducing DEHP in indoor air. The influence of cleaning activities on reducing DEHP concentration in indoor air and on interior surfaces was quantified, and the results showed that DEHP exposure can be reduced by frequent and effective cleaning activities and the removal of existing sources, though it may take a relatively long period of time for the levels to drop significantly. Finally, the model was adjusted to identify the relative contributions of gaseous sorption and particulate‐bound deposition to the overall uptake of semi‐volatile organic compounds (SVOCs) by indoor surfaces as functions of time and the octanol‐air partition coefficient (K_oa) of the chemical. Overall, the model clarifies the mechanisms that govern the emission of phthalates and the subsequent interactions among air, suspended particles, settled dust, and interior surfaces. This model can be easily extended to incorporate additional indoor source materials/products, sorption surfaces, particle sources, and room spaces. It can also be modified to predict the fate and transport of other SVOCs, such as phthalate‐alternative plasticizers, flame retardants, and biocides, and serves to improve our understanding of human exposure to SVOCs in indoor environments.     

Plastics additives in the indoor environment--flame retardants and plasticizers

Phthalic acid esters and phosphororganic compounds (POC) are generally known as semivolatile organic compounds (SVOCs) and are frequently utilized as plasticizers and flame retardants in commercial products. In the indoor environment, both compound groups are released from a number of sources under normal living conditions and accumulate in air and dust. Therefore, inhalation of air and ingestion of house dust have to be considered as important pathways for the assessment of exposure in living habitats. Especially in the case of very young children, the oral and dermal uptake from house dust might be of relevance for risk assessment. A critical evaluation of indoor exposure to phthalates and POC requires the determination of the target compounds in indoor air and house dust as well as emission studies. The latter are usually carried out under controlled conditions in emission test chambers or cells. Furthermore, chamber testing enables the determination of condensable compounds by fogging sampling. In the case of automobiles, specific scenarios have been developed to study material emissions on a test stand or to evaluate the exposure of users while the vehicle is driving. In this review, results from several studies are summarized and compared for seven phthalic esters and eight POC. The available data for room air and dust differ widely depending on investigated compound and compartment. Room air studies mostly include only a limited number of measurements, which makes a statistical evaluation difficult. The situation is much better for house dust measurements. However, the composition of house dust is very inhomogeneous and the result is strongly dependent on the particle size distribution used for analysis. Results of emission studies are presented for building products, electronic equipment, and automobiles. Daily rates for inhalation and dust ingestion of phthalic esters and POC were calculated from 95-percentiles or maximum values. A comparison of the data with results from human biomonitoring studies reveals that only a small portion of intake takes place via the air and dust paths.     

Formaldehyde and acetaldehyde exposure and risk characterization in California early childhood education environments

Little information is available about air quality in early childhood education (ECE) facilities. We collected single‐day air samples in 2010–2011 from 40 ECE facilities serving children ≤6 years old in California and applied new methods to evaluate cancer risk in young children. Formaldehyde and acetaldehyde were detected in 100% of samples. The median (max) indoor formaldehyde and acetaldehyde levels (μg/m³) were 17.8 (48.8) and 7.5 (23.3), respectively, and were comparable to other California schools and homes. Formaldehyde and acetaldehyde concentrations were inversely associated with air exchange rates (Pearson r = ?0.54 and ?0.63, respectively; P < 0.001). The buildings and furnishings were generally >5 years old, suggesting other indoor sources. Formaldehyde levels exceeded California 8‐h and chronic Reference Exposure Levels (both 9 μg/m³) for non‐cancer effects in 87.5% of facilities. Acetaldehyde levels exceeded the U.S. EPA Reference Concentration in 30% of facilities. If reflective of long‐term averages, estimated exposures would exceed age‐adjusted ‘safe harbor levels’ based on California's Proposition 65 guidelines (10^?5 lifetime cancer risk). Additional research is needed to identify sources of formaldehyde and acetaldehyde and strategies to reduce indoor air levels. The impact of recent California and proposed U.S. EPA regulations to reduce formaldehyde levels in future construction should be assessed.     

Radon and Natural Ventilation in Newer Danish Single-Family Houses

Abstract To investigate the effect of ventilation on indoor radon (²²²Rn), simultaneous measurements of radon concentrations and air change rates were made in 117 Danish naturally ventilated slab-on-grade houses built during the period 1984–1989. Radon measurements (based on CR-39 alpha-track detectors) and air change rate measurements (based on the perfluorocarbon tracer technique; PFT) were in the ranges 12–620 Bq m^?3 and 0.16?0.96 h^?1, respectively. Estimates of radon entry rates on the basis of such time-averaged results are presented and the associated uncertainty is discussed. It was found that differences in radon concentrations from one house to another are primarily caused by differences in radon entry rates whereas differences in air change rates are much less important (accounting for only 80,0% of the house-to-house variation). In spite of the large house-to-house variability of radon entry rates it was demonstrated, however, that natural ventilation does have a significant effect on the indoor radon concentration. Most importantly, it was found that the group of houses with an air change rate above the required level of 0.5 h^?1 on average had an indoor radon concentration that was only 50% (0.5±0.1) of that of the group of houses with air change rates below 0.5 h^?1. The reducing effect of increased natural ventilation on the indoor radon concentration was found to be due mainly to dilution of indoor air. No effect could be seen regarding reduced radon entry rates.     

Quantification of the impact of cooking processes on indoor concentrations of volatile organic species and primary and secondary organic aerosols

Cooking is recognized as an important source of particulate pollution in indoor and outdoor environments. We conducted more than 100 individual experiments to characterize the particulate and non‐methane organic gas emissions from various cooking processes, their reaction rates, and their secondary organic aerosol yields. We used this emission data to develop a box model, for simulating the cooking emission concentrations in a typical European home and the indoor gas‐phase reactions leading to secondary organic aerosol production. Our results suggest that about half of the indoor primary organic aerosol emission rates can be explained by cooking. Emission rates of larger and unsaturated aldehydes likely are dominated by cooking while the emission rates of terpenes are negligible. We found that cooking dominates the particulate and gas‐phase air pollution in non‐smoking European households exceeding 1000 μg m^?3. While frying processes are the main driver of aldehyde emissions, terpenes are mostly emitted due to the use of condiments. The secondary aerosol production is negligible with around 2 μg m^?3. Our results further show that ambient cooking organic aerosol concentrations can only be explained by super‐polluters like restaurants. The model offers a comprehensive framework for identifying the main parameters controlling indoor gas‐ and particle‐phase concentrations.