VOC exposures in California early childhood education environments

Little information exists about exposures to volatile organic compounds (VOCs) in early childhood education (ECE) environments. We measured 38 VOCs in single‐day air samples collected in 2010‐2011 from 34 ECE facilities serving California children and evaluated potential health risks. We also examined unknown peaks in the GC/MS chromatographs for indoor samples and identified 119 of these compounds using mass spectral libraries. VOCs found in cleaning and personal care products had the highest indoor concentrations (d‐limonene and decamethylcyclopentasiloxane [D5] medians: 33.1 and 51.4 μg/m³, respectively). If reflective of long‐term averages, child exposures to benzene, chloroform, ethylbenzene, and naphthalene exceeded age‐adjusted “safe harbor levels” based on California's Proposition 65 guidelines (10^?5 lifetime cancer risk) in 71%, 38%, 56%, and 97% of facilities, respectively. For VOCs without health benchmarks, we used information from toxicological databases and quantitative structure–activity relationship models to assess potential health concerns and identified 12 VOCs that warrant additional evaluation, including a number of terpenes and fragrance compounds. While VOC levels in ECE facilities resemble those in school and home environments, mitigation strategies are warranted to reduce exposures. More research is needed to identify sources and health risks of many VOCs and to support outreach to improve air quality in ECE facilities.     

Indoor air quality and thermal comfort in temporary houses occupied after the Great East Japan Earthquake

Thermal conditions and indoor concentrations of aldehydes, volatile organic compounds (VOCs), and NO₂ were investigated in 19 occupied temporary houses in 15 temporary housing estates constructed in Minamisoma City, Fukushima, Japan. The data were collected in winter, spring, and summer in January to July 2012. Thermal conditions in temporary log houses in the summer were more comfortable than those in pre‐fabricated houses. In the winter, the indoor temperature was uncomfortably low in all of the houses, particularly the temporary log houses. Indoor air concentrations for most aldehydes and VOCs were much lower than the indoor guidelines, except for those of p‐dichlorobenzene, acetaldehyde, and total VOCs. The indoor p‐dichlorobenzene concentrations exceeded the guideline (240 μg/m³) in 18% of the temporary houses, and the 10^?3 cancer risk level (91 μg/m³) was exceeded in winter in 21% due to use of moth repellents by the occupants. Indoor acetaldehyde concentrations exceeded the guideline (48 μg/m³) in about half of the temporary houses, likely originating from the wooden building materials. Indoor NO₂ concentrations in the temporary houses were significantly higher in houses where combustion heating appliances were used (0.17 ± 0.11 ppm) than in those where they were not used (0.0094 ± 0.0065 ppm).     

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.     

Indoor air quality,air exchange rates,and radioactivity in new built temporary houses following the Great East Japan Earthquake in Minamisoma,Fukushima

This study measured air exchange rates, indoor concentrations of aldehydes and volatile organic compounds (VOCs), and radioactivity levels at 19 temporary houses in different temporary housing estate constructed in Minamisoma City following the Great East Japan Earthquake. The 19 surveyed houses represented all of the companies assigned to construct temporary houses in that Minamisoma City. Data were collected shortly after construction and before occupation, from August 2011 to January 2012. Mean air exchange rates in the temporary houses were 0.28/h, with no variation according to housing types and construction date. Mean indoor concentrations of formaldehyde, acetaldehyde, toluene, ethylbenzene, m/p‐xylene, o‐xylene, styrene, p‐dichlorobenzene, tetradecane, and total VOCs (TVOCs) were 29.2, 72.7, 14.6, 6.35, 3.05, 1.81, 7.29, 14.3, 8.32, and 901 μg/m³, respectively. The levels of acetaldehyde and TVOCs exceeded the indoor guideline (48 μg/m³) and interim target (400 μg/m³) in more than half of the 31 rooms tested. In addition to guideline chemicals, terpenes (α‐pinene and d‐limonene) and acetic esters (butyl acetate and ethyl acetate) were often detected in these houses. The indoor radiation levels measured by a Geiger–Müller tube (Mean: 0.22 μSv/h) were lower than those recorded outdoors (Mean: 0.42 μSv/h), although the shielding effect of the houses was less than for other types of buildings.     

Carbonyl levels in indoor and outdoor air in Mexico City and Xalapa,Mexico

Carbonyl compounds in air were measured at two houses, three museums, and two offices. All sites lacked air-conditioning systems. Although indoor and outdoor air was measured simultaneously at each site, the sites themselves were sampled in different dates. Mean concentrations were higher in indoor air. Outdoor means concentrations of acetone were the highest in all sites, ranging from 12 to 60 microg m(-3). In general, formaldehyde and acetaldehyde had similar mean concentrations, ranging from 4 to 32 and 6 to 28 microg m(-3), respectively. Formaldehyde and acetone mean indoor concentrations were the highest, ranging from 11 to 97 and 17 to 89 microg m(-3), respectively, followed by acetaldehyde with 5 to 47 microg m(-3). Formaldehyde and acetaldehyde had the highest mean concentration in the offices where there were smokers. Propionaldehyde and butyraldehyde concentrations did not show definite differences between indoor and outdoor air. In general, the highest outdoor and indoor hourly concentrations were observed from 10:00 to 15:00 h. Mean indoor/outdoor ratios of carbonyls exceeded 1. Formaldehyde and acetaldehyde risks were higher in smoking environments.     

Contaminant levels,source strengths,and ventilation rates in California retail stores

This field study measured ventilation rates and indoor air quality in 21 visits to retail stores in California. Three types of stores, such as grocery, furniture/hardware stores, and apparel, were sampled. Ventilation rates measured using a tracer gas decay method exceeded the minimum requirement of California's Title 24 Standard in all but one store. Concentrations of volatile organic compounds (VOCs), ozone, and carbon dioxide measured indoors and outdoors were analyzed. Even though there was adequate ventilation according to standard, concentrations of formaldehyde and acetaldehyde exceeded the most stringent chronic health guidelines in many of the sampled stores. The whole‐building emission rates of VOCs were estimated from the measured ventilation rates and the concentrations measured indoor and outdoor. Estimated formaldehyde emission rates suggest that retail stores would need to ventilate at levels far exceeding the current Title 24 requirement to lower indoor concentrations below California's stringent formaldehyde reference level. Given the high costs of providing ventilation, effective source control is an attractive alternative.     

Contribution of ozone to airborne aldehyde formation in Paris homes

Indoor aldehydes may result from ozone-initiated chemistry, mainly documented by experimental studies. As part of an environmental investigation included in the PARIS birth cohort, the aim of this study was to examine ozone contribution to airborne aldehyde formation in Paris homes. Formaldehyde, acetaldehyde and hexaldehyde levels, as well as styrene, nitrogen dioxide and nicotine concentrations, comfort parameters and carbon dioxide levels, were measured twice during the first year of life of the babies. Ambient ozone concentrations were collected from the closest background station of the regional air monitoring network. Traffic-related nitrogen oxide concentrations in front of the dwellings were estimated by an air pollution dispersion model. Home characteristics and families' way of life were described by questionnaires. Stepwise multiple linear regression models were used to link aldehyde levels with ambient ozone concentrations and a few aldehyde precursors involved in oxidation reactions, adjusting for other indoor aldehyde sources, comfort parameters and traffic-related nitrogen oxides. A 4 and 11% increase in formaldehyde and hexaldehyde levels was pointed out when 8-hour ozone concentrations increased by 20 μg/m³. The influence of potential precursors such as indoor styrene level and frequent use of air fresheners, containing unsaturated volatile organic compounds as terpenes, was also found. Thus, our results suggest that ambient ozone can significantly impact indoor air quality, especially with regard to formaldehyde and hexaldehyde levels.     

Ultrafine,fine, and black carbon particle concentrations in California child‐care facilities

Although many U.S. children spend time in child care, little information exists on exposures to airborne particulate matter (PM) in this environment, even though PM may be associated with asthma and other respiratory illness, which is a key concern for young children. To address this data gap, we measured ultrafine particles (UFP), PM_2.5, PM₁₀, and black carbon in 40 California child‐care facilities and examined associations with potential determinants. We also tested a low‐cost optical particle measuring device (Dylos monitor). Median (interquartile range) concentrations for indoor UFP, gravimetric PM_2.5, real‐time PM_2.5, gravimetric PM₁₀, and black carbon over the course of a child‐care day were 14 000 (11 000‐29 000) particles/cm³, 15 (9.6‐21) μg/m³, 15 (11‐23) μg/m³, 48 (33‐73) μg/m³, and 0.43 (0.25‐0.65) ng/m³, respectively. Indoor black carbon concentrations were inversely associated with air exchange rate (Spearman's rho = ?.36) and positively associated with the sum of all Gaussian‐adjusted traffic volume within a one‐kilometer radius (Spearman's rho = .45) (P‐values <.05). Finally, the Dylos may be a valid low‐cost alternative to monitor PM levels indoors in future studies. Overall, results indicate the need for additional studies examining particle levels, potential health risks, and mitigation strategies in child‐care facilities.     

Indoor air quality in hairdressing salons in Taipei

To improve indoor air quality and to protect public health, Taiwan has enacted the “Indoor Air Quality Act (IAQ Act)” in 2012. For the general public, the indoor air quality in hair salons is important because it is a popular location that people will often visit for hair treatments. However, only a few exposure assessments regarding air pollutants have previously been performed in hair salons. To assess the air quality of hairdressing environments in Taipei, ten hairdressing salons were included for a walk‐through survey in this study. In addition, the airborne concentrations of formaldehyde, volatile organic compounds (VOCs), CO₂, and phthalate esters were also determined in 5 salons. Charcoal, XAD‐2, and OVS‐Tenax tubes were used for the air sampling, while the samples were analyzed with gas chromatography/mass spectrometer. It was found that the products used in hair salons contained various chemicals. In fact, from the walk‐through survey, a total of 387 different ingredients were found on 129 hair product labels. The hair salons were not well ventilated, with CO₂ levels of 600 to 3576 ppm. The formaldehyde concentrations determined in this study ranged from 12.40 to 1.04 × 10³ μg m^?3, and the maximum level was above the permissible exposure limit (PEL) of US Occupational Safety and Health Administration (US OSHA). Additionally, 83% of the samples were with levels higher than the standard regulated by Taiwan's IAQ Act. The concentrations of VOCs and phthalate esters were below the occupational exposure limits (OELs), but higher than what was found in general residential environments. The hair products were considered as the major source of air pollutants because significantly higher concentrations were found around the working areas. The number of perming treatments, the number of workers, and the frequency of using formaldehyde releasing products, were found to be associated with the levels of formaldehyde. This study indicates that efforts are needed to improve the indoor air quality in hairdressing salons in Taipei.     

Performance of ultraviolet photocatalytic oxidation for indoor air cleaning applications

Ultraviolet photocatalytic oxidation (UVPCO) systems for removal of volatile organic compounds (VOCs) from air are being considered for use in office buildings. Here, we report an experimental evaluation of a UVPCO device with tungsten oxide modified titanium dioxide (TiO2) as the photocatalyst. The device was challenged with complex VOC mixtures. One mixture contained 27 VOCs characteristic of office buildings and another comprised 10 VOCs emitted by cleaning products, in both cases at realistic concentrations (low ppb range). VOC conversion efficiencies varied widely, usually exceeded 20%, and were as high as approximately 80% at about 0.03 s residence time. Conversion efficiency generally diminished with increased airflow rate, and followed the order: alcohols and glycol ethers > aldehydes, ketones, and terpene hydrocarbons > aromatic and alkane hydrocarbons > halogenated aliphatic hydrocarbons. Conversion efficiencies correlated with the Henry's law constant more closely than with other physicochemical parameters. An empirical model based on the Henry's law constant and the gas-phase reaction rate with hydroxyl radical provided reasonable estimates of pseudo-first order photocatalytic reaction rates. Formaldehyde, acetaldehyde, acetone, formic acid and acetic acid were produced by the device due to incomplete mineralization of common VOCs. Formaldehyde outlet/inlet concentration ratios were in the range 1.9-7.2. PRACTICAL IMPLICATIONS: Implementation of air cleaning technologies for both VOCs and particles in office buildings may improve indoor air quality, or enable indoor air quality levels to be maintained with reduced outdoor air supply and concomitant energy savings. One promising air cleaning technology is ultraviolet photocatalytic oxidation (UVPCO) air cleaning. For the prototype device evaluated here with realistic mixtures of VOCs, conversion efficiencies typically exceeded the minimum required to counteract predicted VOC concentration increases from a 50% reduction in ventilation. However, the device resulted in the net generation of formaldehyde and acetaldehyde from the partial oxidation of ubiquitous VOCs. Further development of the technology is needed to eliminate these hazardous air pollutants before such a UVPCO device can be deployed in buildings.     

An in‐situ thermally regenerated air purifier for indoor formaldehyde removal

Formaldehyde is a common indoor pollutant that is an irritant and has been classified as carcinogen to humans. Adsorption technology is safe and stable and removes formaldehyde efficiently, but its short life span and low adsorption capacity limit its indoor application. To overcome these limitations, we propose an in‐situ thermally regenerated air purifier (TRAP) which self‐regenerates as needed. This purifier has four working modes: cleaning mode, regeneration mode, exhaust mode, and outdoor air in‐take mode, all of which are operated by valve switching. We developed a real‐scale TRAP prototype with activated carbon as adsorbent. The experimental testing showed that the regeneration ratios for formaldehyde of TRAP were greater than 90% during 5 cycles of adsorption‐regeneration and that through the 5 cycles, there was no damage to the adsorption material as confirmed by scanning electron microscope (SEM) and Brunauer‐Emmett‐Teller (BET) tests. The total energy consumption by the prototype for purifying 1000 m³ indoor air was 0.26 kWh. This in‐situ thermal‐regeneration method can recover the purifier's adsorption ability through at least five cycles.     

A comparative study of human exposures to household air pollution from commonly used cookstoves in Sri Lanka

Solid fuel burning cookstoves are a major source of household air pollution (HAP) and a significant environmental health risk in Sri Lanka. We report results of the first field study in Sri Lanka to include direct measurements of both real‐time indoor concentrations and personal exposures of fine particulate matter (PM_2.5) in households using the two most common stove types in Sri Lanka. A purposive sample of 53 households was selected in the rural community of Kopiwatta in central Sri Lanka, roughly balanced for stove type (traditional or improved ‘Anagi’) and ventilation (chimney present or absent). At each household, 48‐h continuous real‐time measurements of indoor kitchen PM_2.5 and personal (primary cook) PM_2.5 concentrations were measured using the RTI MicroPEM^? personal exposure monitor. Questionnaires were used to collect data related to household demographics, characteristics, and self‐reported health symptoms. All primary cooks were female and of an average age of 47 years, with 66% having completed primary education. Median income was slightly over half the national median monthly income. Use of Anagi stoves was positively associated with a higher education level of the primary cook (P = 0.026), although not associated with household income (P = 0.18). The MicroPEM monitors were well‐received by participants, and this study's valid data capture rate exceeded 97%. Participant wearing compliance during waking hours was on average 87.2% on Day 1 and 83.3% on Day 2. Periods of non‐compliance occurred solely during non‐cooking times. The measured median 48‐h average indoor PM_2.5 concentration for households with Anagi stoves was 64 μg/m³ if a chimney was present and 181 μg/m³ if not. For households using traditional stoves, these values were 70 μg/m³ if a chimney was present and 371 μg/m³ if not. Overall, measured indoor PM_2.5 concentrations ranged from a minimum of 33 μg/m³ to a maximum of 940 μg/m³, while personal exposure concentrations ranged from 34 to 522 μg/m³. Linear mixed effects modeling of the dependence of indoor concentrations on stove type and presence or absence of chimney showed a significant chimney effect (65% reduction; P < 0.001) and an almost significant stove effect (24% reduction; P = 0.054). Primary cooks in households without chimneys were exposed to substantially higher levels of HAP than those in households with chimneys, while exposures in households with traditional stoves were moderately higher than those with improved Anagi stoves. As expected, simultaneously measuring both indoor concentrations and personal exposure levels indicate significant exposure misclassification bias will likely result from the use of a stationary monitor as a proxy for personal exposure. While personal exposure monitoring is more complex and expensive than deploying simple stationary devices, the value an active personal PM monitor like the MicroPEM adds to an exposure study should be considered in future study designs.     

Household air pollution and personal exposure risk of polycyclic aromatic hydrocarbons among rural residents in Shanxi,China

Polycyclic aromatic hydrocarbons (PAHs) are a group of pollutants of widespread concerns. Gaseous and size‐segregated particulate‐phase PAHs were collected in indoor and outdoor air in rural households. Personal exposure was measured and compared to the ingestion exposure. The average concentrations of 28 parent PAHs and benzo(a)pyrene (BaP) were 9000 ± 8390 and 131 ± 236 ng/m³ for kitchen, 2590 ± 2270 and 43 ± 95 ng/m³ for living room, and 2800 ± 3890 and 1.6 ± 0.7 ng/m³ for outdoor air, respectively. The mass percent of high molecular weight (HMW) compounds with 5–6 rings contributed 1.3% to total 28 parent PAHs. Relatively higher fractions of HMW PAHs were found in indoor air compared to outdoor air. Majorities of particle‐bound PAHs were found in the finest PM_0.25, and the highest levels of fine PM_0.25‐bound PAHs were in the kitchen using peat and wood as energy sources. The 24‐h personal PAH exposure concentration was 2100 ± 1300 ng/m³. Considering energies, exposures to those using wood were the highest. The PAH inhalation exposure comprised up to about 30% in total PAH exposure through food ingestion and inhalation, and the population attributable fraction (PAF) for lung cancer in the region was 0.85%. The risks for inhaled and ingested intakes of PAHs were 1.0 × 10^?5 and 1.1 × 10^?5, respectively.     

Particle‐associated polycyclic aromatic hydrocarbons in a representative urban location (indoor‐outdoor) from South Europe: Assessment of potential sources and cancer risk to humans

PM₁₀‐bound polycyclic aromatic hydrocarbons (PAHs) levels were monitored at urban locations (outdoor/indoor) within the city of Madrid between May 2017 and April 2018. Fourteen PAH congeners were measured, potential emission sources were identified as were potential carcinogenic risks. The ΣPAHs averaged 0.577 and 0.186 ng/m³ in outdoor and indoor air, with a high linear correlation per individual mean PAH and month. The largest contributors to the ΣPAHs were the high‐molecular‐weight PAHs. Principal component analysis‐multiple linear regression results showed that emissions from diesel and vehicular processes explained 27% and 23% of the total variance of outdoor and indoor air, while combustion processes accounted for 30% and 25% in ambient and indoor air, respectively. During the cold season, biomass burning plus coal and wood combustion were additional sources of outdoor emissions. The heavy‐, medium‐ and light‐molecular‐weight PAH originating from outdoor sources accounted for 72%, 80%, and ~60% of the indoor levels of the three respective PAH groups. Average BaP concentration was 0.029 and 0.016 ng/m³ in outdoor and indoor air, respectively. Estimated BaPeq concentration averaged 0.072, 0.035, and 0.027 ng/m³ for outdoor, indoor, and indoor‐generated individual PAH concentrations, respectively. The estimated carcinogenic risk falls within the range of acceptable risk targeted by the US‐EPA.     

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.     

Results of the California Healthy Homes Indoor Air Quality Study of 2011–2013: impact of natural gas appliances on air pollutant concentrations

This study was conducted to assess the current impact of natural gas appliances on air quality in California homes. Data were collected via telephone interviews and measurements inside and outside of 352 homes. Passive samplers measured time‐resolved CO and time‐integrated NO_X, NO₂, formaldehyde, and acetaldehyde over ~6‐day periods in November 2011 – April 2012 and October 2012 – March 2013. The fraction of indoor NO_X and NO₂ attributable to indoor sources was estimated. NO_X, NO₂, and highest 1‐h CO were higher in homes that cooked with gas and increased with amount of gas cooking. NO_X and NO₂ were higher in homes with cooktop pilot burners, relative to gas cooking without pilots. Homes with a pilot burner on a floor or wall furnace had higher kitchen and bedroom NO_X and NO₂ compared to homes without a furnace pilot. When scaled to account for varying home size and mixing volume, indoor‐attributed bedroom and kitchen NO_X and kitchen NO₂ were not higher in homes with wall or floor furnace pilot burners, although bedroom NO₂ was higher. In homes that cooked 4 h or more with gas, self‐reported use of kitchen exhaust was associated with lower NO_X, NO₂, and highest 1‐h CO. Gas appliances were not associated with higher concentrations of formaldehyde or acetaldehyde.     

Organic air pollutants inside and outside residences in Shimizu, Japan: levels, sources and risks

Concentrations of 38 organic air pollutants including aromatic hydrocarbons (AHCs), carbonyl compounds (CCs), volatile organic halogenated compounds (VOHCs), and organophosphorus compounds (OPCs) were measured in indoor and outdoor air in an industrial city, Shimizu, Shizuoka Prefecture, Japan. Levels of pollutants tended to be higher indoors than outdoors in both summer and winter except for benzene, carbon tetrachloride, trichloroethylene, tetrachloroethylene, and dichlorvos (DDVP). This trend was especially pronounced for CCs such as formaldehyde and acetaldehyde. For the organic air pollutants, the concentrations of AHCs and VOHCs substantially increased in winter, but not those of CCs and OPCs; the trends were similar for both indoors and outdoors. We investigated possible indoor sources of pollutants statistically. Multiple regression analysis of corresponding indoor and outdoor concentrations and the responses to our questionnaire showed that indoor concentrations of certain AHCs were significantly affected by their outdoor concentrations and cigarette smoking. For formaldehyde, indoor concentrations were significantly affected by house age and the presence of carpet or pets. For p-dichlorobenzene (pDCB), the concentrations in bedroom trended to be higher than those in other indoors and outdoors, suggested that mothballs for clothes present in bedrooms are the principal indoor source of pDCB. We compared indoor and outdoor pollutant concentrations to acceptable risk limits for 11 organic air pollutants. In indoors without smoking samples, the geometric mean concentrations of benzene, formaldehyde, acetaldehyde, carbon tetrachloride, pDCB, and DDVP exceeded the equivalent concentration representing the upper bound of one-in-one-hundred-thousand (1x10(-5)) excess risk over a lifetime of exposure.     

Seasonal and diurnal variations of carbonyl compounds in the urban atmosphere of Guangzhou, China

Seasonal and diurnal variations of carbonyl compounds were investigated at two sampling sites (Liwan and Wushan) in the ambient air of Guangzhou, China. Air samples were collected during 2005 from January to November, and carbonyl compounds were analyzed with HPLC. The results show that carbonyls exhibit distinct seasonal variation. The total concentrations of 21 carbonyls detected ranged from 2.64 to 103.6 μg m⁻³ at Liwan and from 5.46 to 89.9 μg m⁻³ at Wushan, respectively. The average total concentrations of carbonyls at both Liwan and Wushan decreased in order of summer>spring>autumn>winter. Formaldehyde, acetaldehyde, and acetone were the most abundant carbonyl compounds, which accounted for more than 60% of the total concentrations of carbonyls. The mean concentration ratios of summer/winter were all > 1.0 for the total concentrations and the individual carbonyl compound. The diurnal variation of carbonyls was not distinct in this study. The average concentration ratios of formaldehyde/acetaldehyde (C₁/C₂) varied from 0.71 to 1.32 and 0.65 to 1.14 at Liwan and Wushan, respectively, and the average concentration ratios of acetaldehyde/propionaldehyde (C₂/C₃) varied from 5.42 to 7.70 and 5.02 to 13.9 in Liwan and Wushan, respectively. Regarding photochemical reactivity of carbonyls and the ozone production, acetaldehyde, butyraldehyde, formaldehyde, and valeraldehyde account for 75-90% to the total propene-equivalent concentrations, while formaldehyde, acetaldehyde, valeraldehyde, butyraldehyde, and propionaldehyde contribute 89-96% to the total ozone formation potentials (ranging from 105 to 274 μg m^-3). The ozone formation potentials in summer were higher by 1-2 times than those in the other seasons.     

Formaldehyde levels in FEMA‐supplied travel trailers,park models,and mobile homes in Louisiana and Mississippi

In 2006, area physicians reported increases in upper respiratory symptoms in patients living in U.S. Federal Emergency Management Agency (FEMA)‐supplied trailers following Hurricanes Katrina and Rita. One potential etiology to explain their symptoms included formaldehyde; however, formaldehyde levels in these occupied trailers were unknown. The objectives of our study were to identify formaldehyde levels in occupied trailers and to determine factors or characteristics of occupied trailers that could affect formaldehyde levels. A disproportionate random sample of 519 FEMA‐supplied trailers was identified in Louisiana and Mississippi in November 2007. We collected and tested an air sample from each trailer for formaldehyde levels and administered a survey. Formaldehyde levels among all trailers in this study ranged from 3 parts per billion (ppb) to 590 ppb, with a geometric mean (GM) of 77 ppb [95% confidence interval (CI): 70–85; range: 3–590 ppb]. There were statistically significant differences in formaldehyde levels between trailer types (P < 0.01). The GM formaldehyde level was 81 ppb (95% CI: 72–92) among travel trailers (N = 360), 57 ppb (95% CI: 49–65) among mobile homes (N = 57), and 44 ppb (95% CI: 38–53) among park models (N = 44). Among travel trailers, formaldehyde levels varied significantly by brand. While formaldehyde levels varied by trailer type, all types tested had some levels ≥100 ppb.     

Cooking‐related PM2.5 and acrolein measured in grocery stores and comparison with other retail types

We measured particulate matter (PM), acrolein, and other indoor air contaminants in eight visits to grocery stores in California. Retail stores of other types (hardware, furniture, and apparel) were also sampled on additional visits. Based on tracer gas decay data, most stores had adequate ventilation according to minimum ventilation rate standards. Grocery stores had significantly higher concentrations of acrolein, fine and ultrafine PM, compared to other retail stores, likely attributable to cooking. Indoor concentrations of PM_2.5 and acrolein exceeded health guidelines in all tested grocery stores. Acrolein emission rates to indoors in grocery stores had a mean estimate about 30 times higher than in other retail store types. About 80% of the indoor PM_2.5 measured in grocery stores was emitted indoors, compared to only 20% for the other retail store types. Calculations suggest a substantial increase in outdoor air ventilation rate by a factor of three from current level is needed to reduce indoor acrolein concentrations. Alternatively, acrolein emission to indoors needs to be reduced 70% by better capturing of cooking exhaust. To maintain indoor PM_2.5 below the California annual ambient standard of 12 μg/m³, grocery stores need to use air filters with an efficiency rating higher than the MERV 8 air filters commonly used today.