Concentrations and determinants of outdoor, indoor and personal nitrogen dioxide in pregnant women from two Spanish birth cohorts

Determinants of outdoor, indoor and personal concentrations of nitrogen dioxide (NO₂) were assessed in a subset of pregnant women of the Spanish INMA (Environment and Childhood) Study. Home indoor and outdoor NO₂ concentrations were measured during 48 h with passive samplers for 50 and 58 women from the INMA cohorts of Valencia and Sabadell, respectively. Women from Sabadell also carried personal NO₂ samplers during the same period. Data on time–activity patterns, socio-economic characteristics, and environmental exposures were obtained through questionnaires. Multiple linear regression models were developed to predict NO₂ levels.In Valencia, median outdoor NO₂ levels (42 µg/m³) were higher than median indoor levels (36 µg/m³). In Sabadell, personal NO₂ showed the highest median levels (40 µg/m³), followed by indoor (32 µg/m³) and outdoor (29 µg/m³) levels. Personal exposure to NO₂ correlated best with the indoor NO₂ levels. Temporal and traffic-related variables were significant predictors for outdoor NO₂ levels. Thirty-two percent of the indoor NO₂ variability in the two cohorts was explained by outdoor NO₂ levels and the use of the gas appliances. The model for personal exposure accounted for 59% of the variance in NO₂ levels in Sabadell with four predictor variables (outdoor and indoor NO₂ levels, time spent in outdoor environments and time exposed to a gas cooker). No significant association was found between personal or indoor NO₂ levels and exposure to environmental tobacco smoke (ETS) at home.Personal NO₂ levels were found to be strongly influenced by indoor NO₂ concentrations. The study supports the use of time–activity patterns along with indoor measurements to predict personal exposure to traffic-related air pollution.     

Development of a personal exposure monitor for two sizes of inhalable particulates

Measurement of personal exposure to ambient level particulate concentrations is often extremely difficult because of a lack of personal exposure monitors capable of collecting measurable quantities within a meaningful sampling period. A new personal exposure monitor for two fractions of inhalable particulates (i.e., the 3–15 μm aerodynamic diameter and the < 3 μm or respirable fraction) has been developed and characterized. This monitor is capable of collecting a sample of each fraction that is quantifiable with ambient concentrations of inhalable/respirable particulates as low as 25 μg/m³ in a 24-h sampling period. Wind tunnel tests have been made on the particulate personal exposure monitor to determine sampling efficiency as a function of relative wind speed and orientation with respect to the sampler.     

Seasonal variation in outdoor,indoor, and personal air pollution exposures of women using wood stoves in the Tibetan Plateau: Baseline assessment for an energy intervention study

Cooking and heating with coal and biomass is the main source of household air pollution in China and a leading contributor to disease burden. As part of a baseline assessment for a household energy intervention program, we enrolled 205 adult women cooking with biomass fuels in Sichuan, China and measured their 48-h personal exposure to fine particulate matter (PM_2.5) and carbon monoxide (CO) in winter and summer. We also measured the indoor 48-h PM_2.5 concentrations in their homes and conducted outdoor PM_2.5 measurements during 101 (74) days in summer (winter). Indoor concentrations of CO and nitrogen oxides (NO, NO₂) were measured over 48-h in a subset of ~ 80 homes. Women's geometric mean 48-h exposure to PM_2.5 was 80 μg/m³ (95% CI: 74, 87) in summer and twice as high in winter (169 μg/m³ (95% CI: 150, 190), with similar seasonal trends for indoor PM_2.5 concentrations (winter: 252 μg/m³; 95% CI: 215, 295; summer: 101 μg/m³; 95% CI: 91, 112). We found a moderately strong relationship between indoor PM_2.5 and CO (r = 0.60, 95% CI: 0.46, 0.72), and a weak correlation between personal PM_2.5 and CO (r = 0.41, 95% CI: − 0.02, 0.71). NO₂/NO ratios were higher in summer (range: 0.01 to 0.68) than in winter (range: 0 to 0.11), suggesting outdoor formation of NO₂ via reaction of NO with ozone is a more important source of NO₂ than biomass combustion indoors. The predictors of women's personal exposure to PM_2.5 differed by season. In winter, our results show that primary heating with a low-polluting fuel (i.e., electric stove or wood-charcoal) and more frequent kitchen ventilation could reduce personal PM_2.5 exposures. In summer, primary use of a gaseous fuel or electricity for cooking and reducing exposure to outdoor PM_2.5 would likely have the greatest impacts on personal PM_2.5 exposure.     

Oxidative potential and chemical composition of PM2.5 in office buildings across Europe – The OFFICAIR study

In the frame of the OFFICAIR project, indoor and outdoor PM_2.5 samples were collected in office buildings across Europe in two sampling campaigns (summer and winter). The ability of the particles to deplete physiologically relevant antioxidants (ascorbic acid (AA), reduced glutathione (GSH)) in a synthetic respiratory tract lining fluid, i.e., oxidative potential (OP), was assessed. Furthermore, the link between particulate OP and the concentration of the PM constituents was investigated.The mean indoor PM_2.5 mass concentration values were substantially lower than the related outdoor values with a mean indoor/outdoor PM_2.5 mass concentration ratio of 0.62 and 0.61 for the summer and winter campaigns respectively. The OP of PM_2.5 varied markedly across Europe with the highest outdoor OP^AA m⁻³ and OP^GSH m⁻³ (% antioxidant depletion/m³ air) values obtained for Hungary, while PM_2.5 collected in Finland exhibited the lowest values. Seasonal variation could be observed for both indoor and outdoor OP^AA m⁻³ and OP^GSH m⁻³ with higher mean values during winter. The indoor/outdoor OP^AA m⁻³ and OP^GSH m⁻³ ratios were less than one with 4 and 17 exceptions out of the 40 cases respectively. These results indicate that indoor air is generally less oxidatively challenging than outdoors. Correlation analysis revealed that trace elements play an important role in determining OP, in particular, the Cu content. Indoor air chemistry might affect OP since weaker correlations were obtained for indoor PM_2.5. Our findings also suggest that office workers may be exposed to health relevant PM constituents to a different extent within the same building.     

Measurement and health risk assessment of PM2.5, flame retardants,carbonyls and black carbon in indoor and outdoor air in kindergartens in Hong Kong

Indoor air pollution is closely related to children's health. Polybrominated diphenyl ethers (PBDEs) and dechlorane plus (DP) transmitted through indoor PM_2.5 and dust, along with carbonyl compounds and black carbon (BC) aerosol were analysed in five Hong Kong kindergartens. The results showed that 60% of the median PM_2.5 levels (1.3 × 10¹ to 2.9 × 10¹ μg/m³ for indoor; 9.5 to 8.8 × 10¹ μg/m³ for outdoor) in the five kindergartens were higher than the guidelines set by the World Health Organization (2.5 × 10¹ μg/m³). Indoor PM_2.5 mass concentrations were correlated with outdoor PM_2.5 in four of the kindergartens. The PBDEs (0.10–0.64 ng/m³ in PM_2.5; 0.30–2.0 × 10² ng/g in dust) and DP (0.05–0.10 ng/m³ in PM_2.5; 1.3–8.7 ng/g in dust) were detected in 100% of the PM_2.5 and dust samples. Fire retardant levels in the air were not correlated with the levels of dust in this study. The median BC concentrations varied by > 7-fold from 8.8 × 10² ng/m^− 3 to 6.7 × 10³ ng/m^− 3 and cooking events might have caused BC concentrations to rise both indoors and outdoors. The total concentrations of 16 carbonyls ranged from 4.7 × 10¹ μg/m³ to 9.3 × 10¹ μg/m³ indoors and from 1.9 × 10¹ μg/m³ to 4.3 × 10¹ μg/m³ outdoors, whilst formaldehyde was the most abundant air carbonyl. Indoor carbonyl concentrations were correlated with outdoor carbonyls in three kindergartens. The health risk assessment showed that hazard indexes (HIs) HIs of non-cancer risks from PBDEs and DPs were all lower than 0.08, whilst non-cancer HIs of carbonyl compounds ranged from 0.77 to 1.85 indoors and from 0.50 to 0.97 outdoors. The human intake of PBDEs and DP through inhalation of PM_2.5 accounted for 78% to 92% of the total intake. The cancer hazard quotients (HQs) of formaldehyde ranged from 4.5E − 05 to 2.1E − 04 indoors and from 1.9E − 05 to 6.2E − 05 outdoors. In general, the indoor air pollution in the five Hong Kong kindergartens might present adverse effects to children, although different schools showed distinct pollution levels, so indoor air quality might be improved through artificial measures. The data will be useful to developing a feasible management protocol for indoor environments.     

Spatiotemporal analysis and human exposure assessment on polycyclic aromatic hydrocarbons in indoor air,settled house dust,and diet: A review

This review summarizes the published literature on the presence of polycyclic aromatic hydrocarbons (PAH) in indoor air, settled house dust, and food, and highlights geographical and temporal trends in indoor PAH contamination. In both indoor air and dust, ΣPAH concentrations in North America have decreased over the past 30 years with a halving time of 6.7 ± 1.9 years in indoor air and 5.0 ± 2.3 years in indoor dust. In contrast, indoor PAH concentrations in Asia have remained steady. Concentrations of ΣPAH in indoor air are significantly (p < 0.01) higher in Asia than North America. In studies recording both vapor and particulate phases, the global average concentration in indoor air of ΣPAH excluding naphthalene is between 7 and 14,300 ng/m³. Over a similar period, the average ΣPAH concentration in house dust ranges between 127 to 115,817 ng/g. Indoor/outdoor ratios of atmospheric concentrations of ΣPAH have declined globally with a half-life of 6.3 ± 2.3 years. While indoor/outdoor ratios for benzo[a]pyrene toxicity equivalents (BaP_eq) declined in North America with a half-life of 12.2 ± 3.2 years, no significant decline was observed when data from all regions were considered. Comparison of the global database, revealed that I/O ratios for ΣPAH (average = 4.3 ± 1.3), exceeded significantly those of BaP_eq (average = 1.7 ± 0.4) in the same samples. The significant decline in global I/O ratios suggests that indoor sources of PAH have been controlled more effectively than outdoor sources. Moreover, the significantly higher I/O ratios for ΣPAH compared to BaP_eq, imply that indoor sources of PAH emit proportionally more of the less carcinogenic PAH than outdoor sources. Dietary exposure to PAH ranges from 137 to 55,000 ng/day. Definitive spatiotemporal trends in dietary exposure were precluded due to relatively small number of relevant studies. However, although reported in only one study, PAH concentrations in Chinese diets exceeded those in diet from other parts of the world, a pattern consistent with the spatial trends observed for concentrations of PAH in indoor air. Evaluation of human exposure to ΣPAH via inhalation, dust and diet ingestion, suggests that while intake via diet and inhalation exceeds that via dust ingestion; all three pathways contribute and merit continued assessment.     

Upper respiratory symptoms presumably due to studded tire-generated dust

The particulate concentrations in ambient air was elevated in winter seasons in the center of the city of Sendai, presumably due to the extensive use of the studded tires for automobiles; the levels of 493 and 212 μg/m³ were recorded for total particulates and respirable particulates, respectively. The subjective symptom prevalence was investigated by means of self-completion questionnaires in January–February 1984, among the ≥40-yr-old inhabitants of both sexes in the center of Sendai city (annual average total particulate concentration, 28 μg/m³) and also in two whole townships of Wakuya and Tajiri where the air was clean (annual average total particulate concentration, 14 μg/m³). About 17400, 8500, and 6200 respondents were obtained from Sendai, Wakuya, and Tajiri, with an average response rate of 87%. The survey was repeated again in September–October of the same year utilizing one-eighth of the first survey respondents with the response rate of 78%. The analyses of the January–February survey results after adjustment for age and smoking disclosed that prevalence rates of the upper respiratory symptoms such as rhinorrhea, frequent sneezing, phlegm, and sore throat were significantly higher (p < 0.01 ∼ 0.05 depending on the symptoms) among the Sendai population than the control populations in Wakuya and Tajiri in winter. Similar comparative analyses of responses in the September–October survey revealed that the differences in the prevalence rates of the above-stated symptoms did not exist in autumn when the particulate concentrations were low also in Sendai. Possible association of the observed symptoms with elevated particulate concentrations are discussed.     

Studies on indoor air quality in Egypt

Indoor air quality was examined for some gaseous pollutants and particulate matters. In a public library, the indoor/outdoor ratio of gaseous pollutants were found to be dependent on their reactivity, also on the outdoor concentrations and weather conditions. This ratio was 0.6 for SO₂,and 1.3 for CO. The indoor/outdoor ratio of carbon monoxide was found to increase at the higher floors of the same building. Concentrations of indoor particulates was found to be influenced by the outdoor concentrations and the particle size. Analysis indicated that indoor suspended dust contained a significant high concentration of lead as compared with outdoor values. Indoor sources were found to pollute the premises of fossil-fuel equipped homes, thus having carbon monoxide concentrations more than the recognized threshold limit value for industry.     

Detection of fluorotelomer alcohols in indoor environments and their relevance for human exposure

Fluorotelomer alcohols (FTOH) are important precursors of perfluorinated carboxylic acids (PFCA). These neutral and volatile compounds are frequently found in indoor air and may contribute to the overall human exposure to per- and polyfluorinated alkyl substances (PFAS). In this study air samples of ten workplace environments and a car interior were analysed. In addition, extracts and emissions from selected outdoor textiles were analysed in order to establish their potential contribution to the indoor levels of the above-mentioned compounds.Concentrations of FTOHs measured in air ranged from 0.15 to 46.8, 0.25 to 286, and 0.11 to 57.5 ng/m³ for 6:2, 8:2 and 10:2 FTOHs, respectively. The highest concentrations in air were identified in shops selling outdoor clothing, indicating outdoor textiles to be a relevant source of FTOH in indoor workplace environments. Total amounts of FTOH in materials of outdoor textiles accounted for < 0.8–7.6, 12.1–180.9 and 4.65–105.7 μg/dm² for 6:2, 8:2 and 10:2 FTOHs, respectively. Emission from selected textiles revealed emission rates of up to 494 ng/h.The measured data show that a) FTOHs are present in indoor textiles (e.g. carpets), b) they are released at ambient temperatures and c) indoor air of shops selling outdoor textiles contains the highest levels of FTOH. Exposure of humans to perfluorooctanoic acid (PFOA) through absorption of FTOH and subsequent degradation is discussed on the basis of indoor air levels. Calculation of indoor air-related exposure using the median of the measured air levels revealed that exposure is on the same order of magnitude as the recently reported dietary intakes for a background-exposed population. On the basis of the 95th percentile, indoor air exposure to PFOA was estimated to exceed dietary exposure. However, indoor air-related intakes of FTOH are far below the tolerable daily intake (TDI) of PFOA, indicating that there is no risk to health, even when assuming an unrealistic complete degradation of FTOH into PFOA.     

Personal monitoring for nitrogen dioxide exposure: Methodological considerations for a community study

Personal exposure to nitrogen dioxide (NO₂) and time spent in various locations were measured for 66 family members from 19 homes in the Portage, WI area during March 1981. Passive diffusion NO₂ monitors were placed outdoors, in the kitchen, and in one bedroom on each floor of the homes, and were worn by family members. Individuals from gas-cooking homes had significantly higher average NO₂ exposures than those from homes using electricity for cooking (mean difference 19.37 μg/m³). Personal exposures were more closely related to bedroom levels than to kitchen or outdoor concentrations for both cooking fuel groups. Several preliminary models are presented which relate average personal NO₂ exposure to indoor and ambient levels, and also to the proportion of time spent in different locations. These models are capable of explaining nearly 90% of the variation about the mean in personal exposure.     

Per- and polyfluorinated compounds (PFCs) in house dust and indoor air in Catalonia, Spain: implications for human exposure

A total of 27 per- and polyfluorinated compounds (PFCs) were determined in both house dust (n = 10) and indoor air (n = 10) from selected homes in Catalonia, Spain. Concentrations were found to be similar or lower than those previously reported for household microenvironments in other countries. Ten PFCs were detected in all house dust samples. The highest mean concentrations corresponded to perfluorodecanoic acid (PFDA) and perfluorononanoic acid (PFNA), 10.7 ng/g (median: 1.5 ng/g) and 10.4 ng/g (median: 5.4 ng/g), respectively, while the 8:2 fluorotelomer alcohol (FTOH) was the dominating neutral PFC at a concentration of 0.41 ng/g (median: 0.35 ng/g). The indoor air was dominated by the FTOHs, especially the 8:2 FTOH at a mean (median) concentration of 51 pg/m³ (median: 42 pg/m³). A limited number of ionic PFCs were also detected in the indoor air samples. Daily intakes of PFCs were estimated for average and worst case scenarios of human exposure from indoor sources. For toddlers, this resulted in average intakes of ∑ ionic PFCs of 4.9 ng/day (0.33 ng/kg_bw/day for a 15 kg toddlers) and ∑ neutral PFCs of 0.072 ng/day (0.005 ng/kg_bw/day) from house dust. For adults, the average daily intakes of dust were 3.6 and 0.053 ng/day (0.05 and 0.001 ng/kg_bw/day for a 70 kg adult) for ∑ ionic and ∑ neutral PFCs, respectively. The average daily inhalation of ∑ neutral PFCs was estimated to be 0.9 and 1.3 ng/day (0.06 and 0.02 ng/kg_bw/day) for toddlers and adults, respectively. For PFOS, the main ionic PFC detected in indoor air samples, the median intakes (based on those samples where PFOS was detected), resulted in indoor exposures of 0.06 and 0.11 ng/day (0.004 and 0.002 ng/kg_bw/day) for toddlers and adults, respectively. Based on previous studies on dietary intake and drinking water consumption, both house dust and indoor air contribute significantly less to PFC exposure within this population.     

Suspended particulate matter in dwellings — the impact of tobacco smoking

The indoor concentration of suspended particulate matter (SPM) was measured in forty-four retrofitted and tight dwellings, which had electric cooking and were central heated and where the basic ventilation rate in median amounted 0.23 air changes per hour as measured with a tracer dilution method. The indoor concentration of SPM was in median 230 μg/m³ with a strong correlation to the tobacco consumption (r_s=0.716), but with no correlation to the frequency of airing or the basic ventilation rate. Tobacco smoking seems to be the main indoor source of SPM in contemporary dwellings. The importance of these findings is underlined by epidemiologic studies on passive smoking and health. Air quality standards for the ambient air are based on certain risk groups such as infants, children, persons with chronic obstructive lung disorders, and indoor air standards should be based on the same concepts of health protection.     

Personal exposure monitoring to nitrogen dioxide

Measurement of personal exposure to nitrogen dioxide for short and long term was made with a sensitive NO₂ passive sampler by volunteer housewives and office workers in different seasons. These measurements were compared with the simultaneous measurement of outdoor and indoor concentration of the participants. A common result over all the measurements is the potential effect of using an unvented space heater to increase personal exposure. Mean personal exposure and indoor concentration are higher than outdoor levels elevated by the samples exposed to pollutant produced from the heater. Without an NO₂ source indoors, the mean outdoor concentrations are always highest among the data of measurement. A time-weighted indoor/outdoor activity model gives modestly improved estimates of personal exposure over those predicted from measured indoor concentrations alone.     

Short-term dynamics of indoor and outdoor endotoxin exposure: Case of Santiago,Chile, 2012

Indoor and outdoor endotoxin in PM_2.5 was measured for the very first time in Santiago, Chile, in spring 2012. Average endotoxin concentrations were 0.099 and 0.094 [EU/m³] for indoor (N = 44) and outdoor (N = 41) samples, respectively; the indoor–outdoor correlation (log-transformed concentrations) was low: R = − 0.06, 95% CI: (− 0.35 to 0.24), likely owing to outdoor spatial variability.A linear regression model explained 68% of variability in outdoor endotoxins, using as predictors elemental carbon (a proxy of traffic emissions), chlorine (a tracer of marine air masses reaching the city) and relative humidity (a modulator of surface emissions of dust, vegetation and garbage debris). In this study, for the first time a potential source contribution function (PSCF) was applied to outdoor endotoxin measurements. Wind trajectory analysis identified upwind agricultural sources as contributors to the short-term, outdoor endotoxin variability. Our results confirm an association between combustion particles from traffic and outdoor endotoxin concentrations.For indoor endotoxins, a predictive model was developed but it only explained 44% of endotoxin variability; the significant predictors were tracers of indoor PM_2.5 dust (Si, Ca), number of external windows and number of hours with internal doors open. Results suggest that short-term indoor endotoxin variability may be driven by household dust/garbage production and handling. This would explain the modest predictive performance of published models that use answers to household surveys as predictors. One feasible alternative is to increase the sampling period so that household features would arise as significant predictors of long-term airborne endotoxin levels.     

Long-term effects of elemental composition of particulate matter on inflammatory blood markers in European cohorts

BackgroundEpidemiological studies have associated long-term exposure to ambient particulate matter with increased mortality from cardiovascular and respiratory disorders. Systemic inflammation is a plausible biological mechanism behind this association. However, it is unclear how the chemical composition of PM affects inflammatory responses.ObjectivesTo investigate the association between long-term exposure to elemental components of PM and the inflammatory blood markers high-sensitivity C-reactive protein (hsCRP) and fibrinogen as part of the European ESCAPE and TRANSPHORM multi-center projects.MethodsIn total, 21,558 hsCRP measurements and 17,428 fibrinogen measurements from cross-sections of five and four cohort studies were available, respectively. Residential long-term concentrations of particulate matter < 10 μm (PM₁₀) and < 2.5 μm (PM_2.5) in diameter and selected elemental components (copper, iron, potassium, nickel, sulfur, silicon, vanadium, zinc) were estimated based on land-use regression models. Associations between components and inflammatory markers were estimated using linear regression models for each cohort separately. Cohort-specific results were combined using random effects meta-analysis. As a sensitivity analysis the models were additionally adjusted for PM mass.ResultsA 5 ng/m³ increase in PM_2.5 copper and a 500 ng/m³ increase in PM₁₀ iron were associated with a 6.3% [0.7; 12.3%] and 3.6% [0.3; 7.1%] increase in hsCRP, respectively. These associations between components and fibrinogen were slightly weaker. A 10 ng/m³ increase in PM_2.5 zinc was associated with a 1.2% [0.1; 2.4%] increase in fibrinogen; confidence intervals widened when additionally adjusting for PM_2.5.ConclusionsLong-term exposure to transition metals within ambient particulate matter, originating from traffic and industry, may be related to chronic systemic inflammation providing a link to long-term health effects of particulate matter.     

Comparison of indoor and outdoor air quality at two staff quarters in Hong Kong

The indoor and outdoor air quality of two staff quarters of Hong Kong Polytechnic University at Tsim Sha Tsui East (TSTE) and Shatin (ST) were investigated. The air sampling was carried out in winter for about two months starting from January to February of 1996. Fifteen flats from each staff quarter were randomly selected for indoor/outdoor air pollutant measurements. The pollutants measured were NO_x, NO, NO₂, SO₂, CO, and O₃. The variations of pollutant concentrations between indoor and outdoor air were investigated on weekday mornings, weekday evenings, weekend mornings, and weekend evenings. All indoor/outdoor pollutant concentrations measured did not exceed the ASHRAE/NAAQS standard. The carbon monoxide concentrations indoors were systemically higher than those outdoors at the TSTE and the ST quarters, both on weekdays and Sunday, which indicates there are CO sources indoors. Except for CO, the indoor levels of other pollutants (NO_x, NO, NO₂, SO₂, and O₃) are lower than those outdoors. There was a significant correlation (P < 0.05) between indoor and outdoor concentrations for SO₂ and O₃ at both the TSTE and the ST quarters. Except for O₃, the mean concentrations of all the pollutants in the TSTE quarters, both indoor and outdoor, were higher than that of the ST quarters in all sampling periods. All indoor and outdoor O₃ levels were lower at the TSTE quarters than those at the ST quarters. The O₃ ratios of TSTE/ST were 0.72 outdoor and 0.79 indoor. This can be explained by the NO titration reaction through NO conversion to NO₂.     

Personal exposure versus monitoring station data for respirable particles

Personal exposure to respirable particles of 12 subjects working at the same location, but living in various parts of Zagreb, was monitored for 7 consecutive days and compared with simultaneously obtained data from the outdoor network station nearest to subject's home. Although personal exposure is related to the outdoor pollution, other sources play a considerable role. Indoor exposure takes, on the average, more than 80% of the total time. The ratio between average personal exposure and respirable particle levels in the outdoor air decreases with the increased outdoor concentration (r = −0.93), indicating that this relationship might serve as a basis for a rough estimate of possible personal exposure.     

Carcinogenic potential, levels and sources of polycyclic aromatic hydrocarbon mixtures in indoor and outdoor environments and their implications for air quality standards

Both the World Health Organization and the UK Expert Panel on Air Quality Standards (EPAQS) have considered benzo(a)pyrene (BaP) as a marker of the carcinogenic potency of the polycyclic aromatic hydrocarbons (PAH) mixture, when recommending their respective guidelines for PAHs in outdoor air. The aim of this research is to compare the concentrations and relative abundance of individual PAH and their contribution to the overall carcinogenic potential of the PAH mixture in indoor and outdoor environments to assess the suitability of the UK air quality standard derived for outdoor air for use as a guideline for indoor environments. Samples were collected onto filters using active sampling in different indoor and outdoor microenvironments. The ratio of individual compounds to BaP, the BaP equivalent concentrations and the percentage contribution of each individual compound to the total carcinogenic potential of the PAH mixture were calculated. Mean concentrations were generally lower indoors (BaP=0.10 ng/m(3)) than outdoors (BaP=0.19 ng/m(3)), with the exception of indoor environments with wood burners (BaP=2.4 ng/m(3)) or ETS (BaP=0.6 ng/m(3)). The ratio of individual PAHs to BaP showed no significant differences between indoors (e.g. DahA/BaP=0.27) and outdoors (DahA/BaP=0.31). The relative contribution of BaP to the PAH overall carcinogenic potency is similar indoors (49%), outdoors (54%) and in the smelter environment (48%) used by EPAQS to derive the UK Air Quality Standard for ambient air. These results suggest the suitability of BaP as a marker for the carcinogenic potential of the PAH mixture irrespective of the environment. Despite small differences in PAH mixture composition indoors and outdoors, the level of protection afforded by the present EPAQS standard is likely to be similar whether it is applied to indoor or outdoor air.     

Patterns of atmospheric nitrates,sulfate, and hydrogen chloride in the central Ohio River Valley over a one-year period

A study of the seasonal distribution of gaseous and particulate nitrate, sulfate, and hydrogen chloride in the central Ohio Valley is reported. The Ohio Valley has been identified as a significant source of the precursors to atmospheric acids which may be deposited hundreds of kilometers downwind from the source region. This study was undertaken to provide information on the concentration patterns of several species important in acidic deposition. Filter pack samples were collected for 24 h once each week (with some exceptions) from October 1979 through October 1980. The mean concentrations were: 4.05 μg/m³ sulfate, 3.76 μg/m³ total inorganic nitrate (TIN), 2.11 μg/m³ particulate nitrate (apparent), and 1.65 μg/m³ gaseous nitric acid (apparent). Other recent studies in the Ohio Valley yielded gaseous organic nitrate (PAN) concentrations of 2.3 μg/m³ in the spring and 4.8 μg/m³ in summer. Sulfate concentrations were highest in the summer, and both nitric acid and total inorganic nitrate levels were highest in spring and summer. The HNO₃/TIN ratio was also highest during warm weather. A limited number of samples were analyzed for gaseous hydrogen chloride. The concentration of HCl averaged 0.53 μg/m³ over a 2-month period. On a molar basis, HCl and HNO₃ concentrations were nearly equivalent over the 2-month period, suggesting that more attention should be paid to the role of HCl in atmospheric deposition.     

Relationships among personal,indoor and outdoor NO2 measurements

Using integrating NO₂ diffusion dosimeters, personal, indoor and outdoor exposures were measured for nine families in Topeka, Kansas. NO₂ exposures in homes that used gas for cooking were clearly different from those in homes that used electricity. The gas-cooking homes had indoor levels three times the outdoor levels. Members of the gas-cooking households had levels twice those of electric-cooking families and twice the outdoor levels. A linear model that includes outdoor concentrations and stove types explains 77% of the variance in observed NO₂ exposure. The differential NO₂ exposures in homes with and without gas stoves should be considered in epidemiologic studies of the health effects of air pollution.