Exposure to fine particles (PM2.5 and PM1) and black smoke in the general population: personal, indoor, and outdoor levels

Personal exposure to PM(2.5) and PM(1), together with indoor and residential outdoor levels, was measured in the general adult population (30 subjects, 23-51 years of age) of Gothenburg, Sweden. Simultaneously, urban background concentrations of PM(2.5) were monitored with an EPA WINS impactor. The 24-h samples were gravimetrically analyzed for mass concentration and black smoke (BS) using a smokestain reflectometer. Median levels of PM(2.5) were 8.4 microg/m(3) (personal), 8.6 microg/m(3) (indoor), 6.4 microg/m(3) (residential outdoor), and 5.6 microg/m(3) (urban background). Personal exposure to PM(1) was 5.4 microg/m(3), while PM(1) indoor and outdoor levels were 6.2 and 5.2 microg/m(3), respectively. In non-smokers, personal exposure to PM(2.5) was significantly higher than were residential outdoor levels. BS absorption coefficients were fairly similar for all microenvironments (0.4-0.5 10(-5) m(-1)). Personal exposure to particulate matter (PM) and BS was well correlated with indoor levels, and there was an acceptable agreement between personal exposure and urban background concentrations for PM(2.5) and BS(2.5) (r(s)=0.61 and 0.65, respectively). PM(1) made up a considerable amount (70-80%) of PM(2.5) in all microenvironments. Levels of BS were higher outdoors than indoors and higher during the fall compared with spring. The correlations between particle mass and BS for both PM(2.5) vs. BS(2.5) and PM(1) versus BS(1) were weak for all microenvironments including personal exposure. The urban background station provided a good estimate of residential outdoor levels of PM(2.5) and BS(2.5) within the city (r(s)=0.90 and 0.77, respectively). Outdoor levels were considerably affected by long-range transported air pollution, which was not found for personal exposure or indoor levels. The within-individual (day-to-day) variability dominated for personal exposure to both PM(2.5) and BS(2.5) in non-smokers.     

Childhood exposure to PM10: relation between personal, classroom, and outdoor concentrations.

OBJECTIVES: To investigate the validity of outdoor concentrations of particulate matter < 10 microns diameter (PM10) as a measure of exposure in time series studies, and to study the extent to which differences between personal and outdoor PM10 concentrations can be explained. METHODS: Four to eight repeated measurements of personal and outdoor PM10 concentrations were conducted for 45 children, aged 10-12 years, from four schools in Wageningen and Amsterdam, The Netherlands. Repeated PM10 measurements in the classrooms were conducted in three of the schools. Averaging time was 24 hours for the personal and outdoor measurements, and eight hours (daytime) and 24 hours for the classroom measurements. For each child separately, personal exposures were related to outdoor concentrations in a regression analysis. The distribution of the individual correlation and regression coefficients was investigated. Information about factors that might influence personal exposures was obtained by questionnaire. RESULTS: Median Pearson's correlations between personal and outdoor concentrations were 0.63 for children with parents who did not smoke and 0.59 for children with parents who smoked. For children with parents who did not smoke, excluding days with exposure to environmental tobacco smoke (ETS) improved the correlation to a median R of 0.73. The mean personal PM10 concentration was 105 micrograms/m3; on average 67 micrograms/m3 higher than the corresponding outdoor concentrations. The main part of this difference could be attributed to exposure to ETS, to high PM10 concentrations in the classrooms, and to (indoor) physical activity. CONCLUSIONS: The results show a reasonably high correlation between repeated personal and outdoor PM10 measurements within children, providing support for the use of fixed site measurements as a measure of exposure to PM10 in epidemiological time series studies. The large differences between personal and outdoor PM10 concentrations probably result from a child's proximity to particle generating sources and particles resuspended by personal activities.     

北京市冬季住宅内PM_(2.5)暴露水平及室内外关系的研究

目的研究自然通风条件下大规模人群的住宅内PM_(2.5)浓度水平,探讨PM_(2.5)浓度的室内外关系,为评估室内PM_(2.5)暴露提供重要数据支撑和新的研究思路。方法于2013年12月1日—2014年2月28日(2013—2014冬季)在北京市某区开展大规模人群的时间-活动模式和空气污染暴露影响因素调查,基于调查数据及PM_(2.5)空气动力学特性建立住宅内PM_(2.5)的质量平衡模型,利用环境监测站点PM_(2.5)监测数据模拟住宅内PM_(2.5)浓度,计算室内外PM_(2.5)浓度比(I/O),并探讨PM_(2.5)室内外关系。结果本研究1 092个样本2013—2014冬季住宅内PM_(2.5)浓度范围为26~167μg/m~3,PM_(2.5)浓度的中位数为73μg/m~3,四分位数间距为34μg/m~3。室外PM_(2.5)浓度范围分别为0~33μg/m~3、34~65μg/m~3、66~129μg/m~3、≥130μg/m~3时,PM_(2.5)浓度I/O分别为1.75、1.05、0.76和0.63;随着室外PM_(2.5)浓度的增加,I/O呈减小趋势,且分布趋于集中。结论基于大规模人群的时间-活动模式和空气污染暴露影响因素调查建立质量平衡模型,可实现大规模人群室内PM_(2.5)浓度的连续模拟。     

Personal PM2.5 exposure and markers of oxidative stress in blood

Ambient particulate air pollution assessed as outdoor concentrations of particulate matter less than or equal to 2.5 micro m in diameter (PM(2.5)) in urban background has been associated with cardiovascular diseases at the population level. However, the significance of individual exposure and the involved mechanisms remain uncertain. We measured personal PM(2.5) and carbon black exposure in 50 students four times in 1 year and analyzed blood samples for markers of protein and lipid oxidation, for red blood cell (RBC) and platelet counts, and for concentrations of hemoglobin and fibrinogen. We analyzed protein oxidation in terms of gamma-glutamyl semialdehyde in hemoglobin (HBGGS) and 2-aminoadipic semialdehyde in hemoglobin (HBAAS) and plasma proteins (PLAAS), and lipid peroxidation was measured as malondialdehyde (MDA) in plasma. Median exposures were 16.1 micro g/m(3) for personal PM(2.5) exposure, 9.2 micro g/m(3) for background PM(2.5) concentration, and 8.1 X 10(-6)/m for personal carbon black exposure. Personal carbon black exposure and PLAAS concentration were positively associated (p < 0.01), whereas an association between personal PM(2.5) exposure and PLAAS was only of borderline significance (p = 0.061). A 3.7% increase in MDA concentrations per 10 micro g/m(3) increase in personal PM(2.5) exposure was found for women (p < 0.05), whereas there was no significant relationship for the men. Similarly, positive associations between personal PM(2.5)exposure and both RBC and hemoglobin concentrations were found only in women (p < 0.01). There were no significant relationships between background PM(2.5) concentration and any of the biomarkers. This suggests that exposure to particles in moderate concentrations can induce oxidative stress and increase RBCs in peripheral blood. Personal exposure appears more closely related to these biomarkers potentially related to cardiovascular disease than is ambient PM(2.5) background concentrations.     

Indoor/outdoor PM10 and PM2.5 in Bangkok, Thailand

Twenty-four-hour averaged PM10 and PM2.5 concentrations were obtained by using 4-liter-per-minute-pumps and impactors in microenvironments of a busy shopping district and a university hospital campus. In both areas, most people live directly adjacent to their worksites--minimizing the need to measure commuting exposure as part of total daily exposure. Co-located samplers were set in indoor microenvironments, the near-ambient zone of the households, and at nearby streetside central ambient monitoring stations. Smoking and use of other indoor PM sources were recorded daily via questionnaires. Consistent with previous studies, smoking and the use of charcoal stoves increased indoor particulate matter levels. The sampled air-conditioned hospital area had substantially lower particle concentrations than outdoors. A simple total exposure model was used to estimate the human exposure. The averaged ratios of co-located PM2.5/PM10 concentrations in various microenvironments are reported for each location. A single daily indoor average PM10 concentration for all households measured in a given sampling day is calculated for correlation analysis. Results showed that day-to-day fluctuations of these calculated indoor PM10 levels correlated well with near-ambient data and moderately well with ambient data collected at the nearby central monitoring site. This implies that ambient monitors are able to capture the daily variations of indoor PM levels or even personal exposure and may help explain the robust association of ambient PM levels and health effects found in many epidemiological studies. Absolute PM exposures, however, were substantially underestimated by ambient monitors in the shopping district, probably because of strong local sources.     

Personal exposures to PM(2.5) and polycyclic aromatic hydrocarbons and their relationship to environmental tobacco smoke at two locations in Greece

In the context of a large-scale molecular epidemiology study of biomarkers of genotoxicity of air pollution, 24-h mean personal exposures to airborne PM(2.5) (particulate matter <2.5 microm) and associated polycyclic aromatic hydrocarbon (PAHs) were measured in 194 non-smoking technical institute students living in the city of Athens, Greece (an area with moderately high levels of air pollution) and the nearby small town of Halkida anticipated to have lower pollution levels. Extensive information relevant to the assessment of long-term and recent exposure to PAH was obtained from questionnaires as well as a time-location-activity diary (TLAD) which was kept by all subjects during a 4-day observation period. During the last 24 h of this period, subjects underwent personal exposure monitoring for PM(2.5) and PAH, while a sample of blood was donated at the end of this period. All subjects were monitored in this way twice; once during a winter season (October-February) and once during the following summer season (June-September). Nine subjects with plasma cotinine levels above 20 ng/ml were considered as unreported smokers and excluded from the study. Winter PM(2.5) exposures were lower in Athens (geometric mean 39.7 microg/m(3)) than Halkida (geometric mean 56.2 microg/m(3)) (P<0.001), while there was no significant location difference during the summer (Athens: geometric mean 32.3 microg/m(3), Halkida: geometric mean 32.9 microg/m(3); P=0.79). On the other hand, PAH exposures (sum of the eight carcinogenic PAHs) were significantly higher in Athens than in Halkida during the winter (Athens: geometric mean 8.26 ng/m(3), Halkida: geometric mean 5.80 ng/m(3); P<0.001) as well as during the summer (Athens: geometric mean 4.44 ng/m(3), Halkida: geometric mean 1.48 ng/m(3); P<0.001). There was a significant difference in the profile of the PAH exposures at the two locations, the proportion of lighter PAH (benzo[a]anthracene, chrysene [CHRYS], benzo[k]fluoranthene, and benzo[b]fluoranthene) being higher, and that of heavier PAH (benzo[ghi]perylene [BPer] and indeno[1,2,3,cd]pyrene) lower, in Halkida than in Athens, regardless of season. This difference appeared to be related to individual exposure to environmental tobacco smoke (ETS), as indicated by (a) the correlation at the individual level between the CHRYS/BPer ratio and declared time of recent exposure to ETS as well as plasma cotinine levels, especially during the winter; (b) the parallel variation of the mean levels of all three markers (declared ETS exposure, cotinine levels, CHRYS/BPer ratio) among three subgroups of subjects (Athens subjects who had lowest levels of all three markers; Halkida subjects other than those living in the institute campus area; and Halkida subjects living in the institute campus area who had the highest levels of all three markers). This demonstrates that ETS can have a distinctive effect on the PAH exposure profile of subjects exposed to relatively low levels of urban air pollution.     

Particulate matter measurements PM2.5 and PM10 in Rome: comparison indoor/outdoor

The concentration of airborne particulate matter (PM2.5 and PM10) was assessed over 12 months (1999-2000) both outdoor and indoor (workplaces and homes without major PM sources) through a manual gravimetric method. Mean concentration values outdoors were moderately lower than indoor concentrations in summer, but higher in winter. The correlations between outdoor and indoor values are statistically significant, especially for PM2.5 in winter. The position of indoor sites with respect to street level was immaterial as far as mean values is concerned, whilst maximum values presented some differences accordingly. Day-to-day variability was higher outside than inside, especially in winter. The PM2.5/PM10 ratio was higher indoors, probably owing to the higher sedimentation speed of the coarse fraction.     

Personal exposure to PM(2.5) and urinary hydroxy-PAH levels in bus drivers exposed to traffic exhaust, in Trujillo, Peru

Public transport vehicle drivers, especially in highly polluted or trafficked areas, are exposed to high levels of air pollutants. In this study, we assessed the influence of traffic on levels of hydroxy polycyclic aromatic hydrocarbons (OH-PAHs) in commercial bus drivers in Trujillo, Peru, by measuring the within-shift changes in the urinary whole weight and creatinine-corrected concentrations of the PAH metabolites. We measured personal PM(2.5) as a proxy of exposure to traffic emission. Urine samples were collected daily from two bus drivers and three minivan drivers in Trujillo, pre-, mid-, post-work shift and on days when the drivers were off work (total n = 144). Ten OH-PAH metabolites were measured in the urine samples. Drivers were also monitored for exposure to PM(2.5) (n = 41). Daily work shift (mean = 13.1 ± 1.3 hr) integrated PM(2.5) was measured in the breathing zones of the drivers for an average of 10.5 days per driver. The differences across shift in OH-PAH concentrations were not statistically significant except for urinary 2-hydroxyfluorene (2-FLU) (p = 0.04) and 4-hydroxyphenanthrene (4-PHE)?(p?= 0.01) and creatinine-corrected 4-hydroxyphenanthrene (p = 0.01). Correlation between pairs of hydroxy-PAHs (ρ = 0.50 to 0.93) were highest for mid-shift samples. Concentrations of PM(2.5) (geometric mean = 64 μg/m(3); 95% confidence limits = 52 μg/m(3), 78 μg/m(3)) is similar to those measured in many other studies of traffic exposure. There was significant change across work shift for concentrations of only two of the OH-PAHs (2-FLU and 4-PHE). Results indicate that the drivers may have had limited time for clearance of PAH exposure from the body between work shifts. Comparisons of the concentrations of creatinine-corrected hydroxy-PAH to those reported in other studies indicate that exposure of public transport drivers to PAH could be similar. By following the subjects over multiple days, this study gives an indication of appropriate exposure situations for the use of hydroxy-PAHs and will be beneficial in designing future occupational studies of PAH exposure.     

Personal exposure and health effect relationship for NO2 with urinary hydroxyproline to creatinine ratio as indicator

Establishment of an exposure-effect relationship was attempted between personal nitrogen dioxide (NO2) exposure and urinary hydroxyproline to creatinine ratio of approximately 800 adult women, who were mothers of primary schoolchildren living in two communities around Tokyo. Daily average of the personal NO2 exposure (ENO2) was measured during wintertime by a newly developed personal monitor exposed for 24 hours. The hydroxyproline to creatinine ratio (HOP:C) in the urine sample collected early in the morning of the day for ENO2 measurement was used as a biochemical indicator of the health effect of NO2 exposure. The HOP:C was found to have significant correlation with ENO2 and number of cigarettes smoked actively and passively. ENO2, however, had no correlation with the intensity of the smoking levels; they might affect HOP:C independently. Stepwise multiple regression analysis revealed that HOP:C could be predicted by ENO2 and smoking habits at a high confidence level. The regression analysis of the active smokers' group indicated that a few cigarettes was enough to increase the HOP:C, while in the case of passive smoking, HOP:C increased proportionally to the number of cigarettes.     

Comparing exposure metrics in the relationship between PM2.5 and birth weight in California

Although studies suggest that air pollution is linked to perinatal outcomes, the geographic characterization of exposure to pollution differs between the studies. We compared neighborhood- and county-level measures of air pollution exposure, while examining the association between particulate matter less than 2.5 microm in aerodynamic diameter (PM(2.5)) and birth weight among full-term births in California in 2000. To reduce the effects of demographic variability, our analysis was limited to two populations of 8579 non-Hispanic white and 8114 Hispanic mothers who were married, between 20 and 30 years of age, completed at least a high school education, and gave birth for the first time. Measurements from the nearest monitor, and average and distance-weighted average of monitors within a 5-mile radius from each mother's residence (constituting neighborhood metrics) and the mean of monitors within each mother's county of residence were considered. PM(2.5) measurements, provided by the California Air Resources Board, were calculated to correspond to each mother's 9-month gestation period. Although metrics within the 5-mile radii and the county were highly correlated (r(2)=0.78), the county-level metric provided a stronger association between PM(2.5) and birth weight (beta=-4.04, 95% confidence interval =-6.71, -1.37) than the metric for the average of all monitors within 5-miles (beta=-1.38, 95% confidence interval =-3.36, 0.60) among non-Hispanic white mothers; similar results were observed among the Hispanic sample of mothers. Consequently, inferences from studies using different definitions of air pollution exposure may not be comparable.     

Formaldehyde levels in Sweden: personal exposure, indoor, and outdoor concentrations

Formaldehyde is a ubiquitous environmental pollutant and is probably carcinogenic to humans. Exposure to formaldehyde was investigated in the general population with personal as well as stationary measurements. The results from two campaigns in two Swedish cities are presented, including measurements of personal exposure among a total of 65 randomly selected subjects together with simultaneous measurements of individual indoor and outdoor concentrations. Diffusive GMD samplers were placed in the breathing zone, in the participants' bedrooms, and outside their homes for 24 h in campaign A and six days in campaign B. Repeated measurements were also conducted in order to study the variability between and within individuals. Median personal exposure to formaldehyde was 22 microg/m(3) (campaign A) and 23 microg/m(3) (campaign B), which is within the guideline value range of 12-60 microg/m(3) proposed in Sweden. Bedroom concentrations were generally slightly higher than personal exposure, while outdoor concentrations (measured only in campaign B) were low. In campaign B, the stationary measurements were used to model personal exposure. Bedroom concentrations were found to explain 90% of the variation of the measured personal exposure and predicted personal exposure nearly as well as an extended model that also included the outdoor contribution. Subjects living in single-family houses had significantly higher exposure to formaldehyde compared with subjects living in apartments. The 24-h and 6-day sampling periods yield a relatively low within-individual variability for formaldehyde measurements with GMD samplers.     

Influence of ambient (outdoor) sources on residential indoor and personal PM2.5 concentrations: analyses of RIOPA data

The Relationship of Indoor, Outdoor and Personal Air (RIOPA) study was designed to investigate residential indoor, outdoor and personal exposures to several classes of air pollutants, including volatile organic compounds, carbonyls and fine particles (PM2.5). Samples were collected from summer, 1999 to spring, 2001 in Houston (TX), Los Angeles (CA) and Elizabeth (NJ). Indoor, outdoor and personal PM2.5 samples were collected at 212 nonsmoking residences, 162 of which were sampled twice. Some homes were chosen due to close proximity to ambient sources of one or more target analytes, while others were farther from sources. Median indoor, outdoor and personal PM2.5 mass concentrations for these three sites were 14.4, 15.5 and 31.4 microg/m3, respectively. The contributions of ambient (outdoor) and nonambient sources to indoor and personal concentrations were quantified using a single compartment box model with measured air exchange rate and a random component superposition (RCS) statistical model. The median contribution of ambient sources to indoor PM2.5 concentrations using the mass balance approach was estimated to be 56% for all study homes (63%, 52% and 33% for California, New Jersey and Texas study homes, respectively). Reasonable variations in model assumptions alter median ambient contributions by less than 20%. The mean of the distribution of ambient contributions across study homes agreed well for the mass balance and RCS models, but the distribution was somewhat broader when calculated using the mass balance model with measured air exchange rates.     

Indoor, outdoor, and regional summer and winter concentrations of PM10, PM2.5, SO4(2)-, H+, NH4+, NO3-, NH3, and nitrous acid in homes with and without kerosene space heaters

Twenty-four-hour samples of PM10 (mass of particles with aerodynamic diameter < or = 10 microm), PM2.5, (mass of particles with aerodynamic diameter < or = 2.5 microm), particle strong acidity (H+), sulfate (SO42-), nitrate (NO3-), ammonia (NH3), nitrous acid (HONO), and sulfur dioxide were collected inside and outside of 281 homes during winter and summer periods. Measurements were also conducted during summer periods at a regional site. A total of 58 homes of nonsmokers were sampled during the summer periods and 223 homes were sampled during the winter periods. Seventy-four of the homes sampled during the winter reported the use of a kerosene heater. All homes sampled in the summer were located in southwest Virginia. All but 20 homes sampled in the winter were also located in southwest Virginia; the remainder of the homes were located in Connecticut. For homes without tobacco combustion, the regional air monitoring site (Vinton, VA) appeared to provide a reasonable estimate of concentrations of PM2.5 and SO42- during summer months outside and inside homes within the region, even when a substantial number of the homes used air conditioning. Average indoor/outdoor ratios for PM2.5 and SO42- during the summer period were 1.03 +/- 0.71 and 0.74 +/- 0.53, respectively. The indoor/outdoor mean ratio for sulfate suggests that on average approximately 75% of the fine aerosol indoors during the summer is associated with outdoor sources. Kerosene heater use during the winter months, in the absence of tobacco combustion, results in substantial increases in indoor concentrations of PM2.5, SO42-, and possibly H+, as compared to homes without kerosene heaters. During their use, we estimated that kerosene heaters added, on average, approximately 40 microg/m3 of PM2.5 and 15 microg/m3 of SO42- to background residential levels of 18 and 2 microg/m3, respectively. Results from using sulfuric acid-doped Teflon (E.I. Du Pont de Nemours & Co., Wilmington, DE) filters in homes with kerosene heaters suggest that acid particle concentrations may be substantially higher than those measured because of acid neutralization by ammonia. During the summer and winter periods indoor concentrations of ammonia are an order of magnitude higher indoors than outdoors and appear to result in lower indoor acid particle concentrations. Nitrous acid levels are higher indoors than outdoors during both winter and summer and are substantially higher in homes with unvented combustion sources.     

PM 2.5 and PAH concentrations in urban atmosphere of Tiruchirappalli, India

Airborne PM 2.5 and polycyclic aromatic hydrocarbons (PAHs) bound to it were determined from March 2009 to February 2010 at different locations in Tiruchirappalli City, Southern India using fine particulate sampler and high performance liquid chromatography. Average ∑9 PAHs concentrations at four sampling stations were 333.7, 202.6, 265.9, and 232.7 ng/m³, respectively. Highest concentration of PAHs was observed during northeast monsoon season (301.5 ng/m³) and lowest in southwest monsoon (216 ng/m³). Low and medium molecular weight PAHs such as phenanthrene, anthracene, benzo(a)anthracene and chrysene were observed in all seasons. Principal compound analysis revealed gasoline and diesel vehicular emissions as major sources for PAHs compounds.     

北美、欧洲和亚洲地区PM2.5暴露与人群死亡率关系Meta分析的对比

目的 采用Meta分析方法评价近年来国内外大气细颗粒物(PM2.5)暴露对人群每日死亡率的影响.方法 检索PubMed和Web of Science数据库,收集并筛选所有近年来PM2.5暴露与人群死亡关系的文献资料,并对文献中相关的数据信息进行提取,通过Meta分析对近年来亚洲、北美洲和欧洲3个地区的PM2.5暴露与每日死亡率的关系进行分析评价.结果 经过分析得出亚洲地区、北美地区和欧洲地区的PM2.5的浓度每升高10 μg/m3,居民死亡率百分比分别增加0.96％ (95％CI:0.94％～0.97％)、1.05％ (95％ CI:1.03％～1.08％)和1.80％(95％CI:1.23％～2.36％).结论 不同地区PM2.5浓度升高后居民死亡率均有所升高,但亚洲地区的死亡率增幅低于欧洲、北美地区.     

Relationship between indoor and outdoor levels of fine particle mass, particle number concentrations and black smoke under different ventilation conditions

Fine particle mass (PM(2.5)), black smoke (BS) and particle number concentration (NC) were measured simultaneously indoors and outdoors at an urban location in Erfurt, Germany. Measurements were conducted during 2-month periods in summer and winter. Different ventilation modes were applied during each measurement period: windows closed; windows opened widely for 15 min twice per day; windows and door across the room opened widely for 5 min twice per day and windows tilted open all day long. The lowest indoor/outdoor (I/O) ratios for all pollutants were found for closed windows, whereas the ratios for ventilated environments were higher. For closed windows, the I/O ratios for PM(2.5) are larger than the corresponding values for BS and NC (0.63 vs. 0.44 or 0.33, respectively) probably due to lower penetration factors for particles sizes <500 nm and higher deposition rates for ultrafine particles (<100 nm). The largest differences for the I/O ratios between closed and tilted windows were found for NC (0.33 vs. 0.78). The indoor and outdoor levels of PM(2.5) and BS were strongly correlated for all ventilation modes. The linear regression models showed that more than 75% of the daily indoor variation could be explained by the daily outdoor variation for those pollutants. However, the correlation between indoor and outdoor NC for ventilation twice a day was weak. It indicates that rapid changes of the air exchange rates during the day may affect the correlation and regression analysis of NC indoor and outdoor concentrations. This effect was not observed for PM(2.5) or BS. This study shows the importance of the indoor air aerosol measurements for health effects studies and the need for more research on I/O transport mechanisms for NC.     

Personal exposure to environmental tobacco smoke: salivary cotinine, airborne nicotine, and nonsmoker misclassification.

A large study was conducted to assess exposure to environmental tobacco smoke (ETS) in a geographically dispersed study population using personal breathing zone air sampling and salivary cotinine levels. Approximately 100 self-reported nonsmoking subjects in each of 16 metropolitan areas were recruited for this investigation. Cumulative distributions of salivary cotinine levels for subjects in smoking and nonsmoking homes and workplaces exhibited a general trend of decreasing salivary cotinine levels with decreasing time spent in smoking environments. Median salivary cotinine levels for the four experimental cells in the study (product of smoking and nonsmoking home and workplaces) were comparable to those reported for a large national study of serum levels of cotinine (Third National Health and Nutrition Examination Survey, NHANES III), when the latter was corrected for expected differences between serum and saliva concentrations. However, the most highly exposed group in this study had a median salivary cotinine concentration approximately a factor of 2 greater than that of the comparable group in the NHANES III study. Misclassification rates, both simple (for self-reported nonsmokers) and complex (self-reported lifetime never smokers), were near the median of those reported for other studies. Estimated misclassification rates for self-reported lifetime never-smoking females are sufficiently high (2.95% using a discrimination level of 106 ng/ml) that, if used in the Environmental Protection Agency (EPA) risk assessment related to ETS and lung cancer, would place the lower 90% confidence interval (CI) for relative risk at nearly 1.00, i.e., no statistically significant increased risk. For the 263 most highly exposed subjects in the study whose self-reported nonsmoking status was accurate, the correlation between airborne exposure to nicotine and average salivary cotinine is so small, on an individual basis, that it makes the relationship useless for estimating exposure on a quantitative basis. When subjects are grouped according to likely categories of nicotine exposure, correlation between group median airborne nicotine exposure and salivary cotinine level increases dramatically. The comparison improves for the most highly exposed subjects, suggesting that such quantitative comparisons are useful for only those subjects who are exposed to the higher levels of ETS. However, airborne nicotine exposure for most of the subjects does not account for estimated systemic levels of nicotine, based on salivary cotinine levels.     

The effect of outdoor air and indoor human activity on mass concentrations of PM(10), PM(2.5), and PM(1) in a classroom

The 12-h mass concentration of PM₁₀, PM_2.5, and PM₁ was measured in a lecturing room by means of three co-located Harvard impactors. The filters were changed at 8 AM and at 8 PM to cover the periods of presence and absence of students. Concentrations were assessed by gravimetry. Ambient PM₁₀ data were available for corresponding 12-h intervals from the nearest state air-quality-monitoring network station. The data were pooled into four periods according to the presence and absence of students—Monday-Thursday day (workday daytime), Monday-Thursday night (workday night), Friday-Sunday day (weekend daytime), and Friday-Sunday night (weekend night). Average indoor workday daytime concentrations were 42.3, 21.9 and 13.7 μg m⁻³, workday night were 20.9, 19.1 and 15.2 μg m⁻³, weekend daytime were 21.9, 18.1 and 11.4 μg m⁻³, and weekend night were 24.5, 21.3, and 15.6 μg m⁻³ for PM₁₀, PM_2.5, and PM₁, respectively. The highest 12-h mean, median, and maximum (42.3, 43.0, and 76.2 μg m⁻³, respectively) indoor concentrations were recorded on workdays during the daytime for PM₁₀. The statistically significant (r=0.68,P<0.0009) correlation between the number of students per hour per day and the indoor coarse fraction calculated as PM_10−2.5 during daytime on workdays indicates that the presence of people is an important source of coarse particles indoor. On workdays, the daytime PM₁₀ indoor/outdoor ratio was positively associated (r=0.93) with an increasing indoor coarse fraction (PM_10-2.5), also indicating that an important portion of indoor PM₁₀ had its source inside the classroom. With the exception of the calculated coarse fraction (PM_10-2.5), all of the measured indoor particulate matter fractions were significantly highly correlated with outdoor PM₁₀ and negatively correlated with wind velocity, showing that outdoor levels of particles influence their indoor concentrations.     

2015年中国西南地区PM2.5长期暴露所致超额死亡人数评估

目的 估计2015年中国西南地区PM2.5长期暴露所致超额死亡人数,为我国西南地区空气污染防控相关政策的制定提供科学参考。方法 本研究PM2.5和人口数据来自NASA,空间分辨率为1km×1km,采用全球暴露-死亡关系模型分别估计PM2.5对局部缺血性心脏病（IHD）、慢性阻塞性肺疾病（COPD）和肺癌（LNC）死亡的相对危险度,最后根据超额死亡人数评估模型估计各省市PM2.5长期暴露所致超额死亡人数。 结果 2015年中国西南地区PM2.5污染所致超额死亡总人数为13.76万人,其中IHD、COPD和LNC超额死亡人数分别为6.45万、5.41万和1.90万;四川省、重庆市、云南省和贵州省的PM2.5污染的超额死亡人数分别为6.07万、2.24万、2.57万和2.88万。结论 中国西南地区应重点关注和防治PM2.5污染所致局部缺血性心脏病死亡,并根据各地区实际情况制定合理的大气PM2.5污染防控措施,减轻空气污染对人群的健康危害。