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1.
ABSTRACT We conducted a multi-pollutant exposure study in Baltimore, MD, in which 15 non-smoking older adult subjects (>64 years old) wore a multi-pollutant sampler for 12 days during the summer of 1998 and the winter of 1999. The sampler measured simultaneous 24-hr integrated personal exposures to PM 25, PM 10, SO 4 2-, O 3, NO 2, SO 2, and exhaust-related VOCs. Results of this study showed that longitudinal associations between ambient PM 2.5 concentrations and corresponding personal exposures tended to be high in the summer (median Spearman's r = 0.74) and low in the winter (median Spearman's r = 0.25). Indoor ventilation was an important determinant of personal PM 2.5 exposures and resulting personal-ambient associations. Associations between personal PM 25 exposures and corresponding ambient concentrations were strongest for well-ventilated indoor environments and decreased with ventilation. This decrease was attributed to the increasing influence of indoor PM 2 5 sources. Evidence for this was provided by SO 4 2-measurements, which can be thought of as a tracer for ambient PM 25. For SO 4 2-, personal-ambient associations were strong even in poorly ventilated indoor environments, suggesting that personal exposures to PM 2.5 of ambient origin are strongly associated with corresponding ambient concentrations. The results also indicated that the contribution of indoor PM 2.5 sources to personal PM 2.5 exposures was lowest when individuals spent the majority of their time in well-ventilated indoor environments. Results also indicate that the potential for confounding by PM 2.5 co-pollutants is limited, despite significant correlations among ambient pollutant concentrations. In contrast to ambient concentrations, PM 2.5 exposures were not significantly correlated with personal exposures to PM 2.5-10, PM 2.5 of non-ambient origin, O 3, NO 2, and SO 2. Since a confounder must be associated with the exposure of interest, these results provide evidence that the effects observed in the PM 2.5 epidemiologic studies are unlikely to be due to confounding by the PM 2.5 co-pollutants measured in this study. 相似文献
2.
Outdoor levels of fine particles (PM 2.5; particles <2.5 μm) have been associated with cardiovascular health. Persons with existing cardiovascular disease have been suggested to be especially vulnerable. It is unclear, how well outdoor concentrations of PM 2.5 and its constituents measured at a central site reflect personal exposures in Southern European countries. The objective of the study was to assess the relationship between outdoor and personal concentrations of PM 2.5, absorbance and sulphur among post-myocardial infarction patients in Barcelona, Spain.Thirty-eight subjects carried personal PM 2.5 monitors for 24-h once a month (2–6 repeated measurements) between November 2003 and June 2004. PM 2.5 was measured also at a central outdoor monitoring site. Light absorbance (a proxy for elemental carbon) and sulphur content of filter samples were determined as markers of combustion originating and long-range transported PM 2.5, respectively.There were 110, 162 and 88 measurements of PM 2.5, absorbance and sulphur, respectively. Levels of outdoor PM 2.5 (median 17 μg m 3) were lower than personal PM 2.5 even after excluding days with exposure to environmental tobacco smoke (ETS) (median after exclusion 27 μg m 3). However, outdoor concentrations of absorbance and sulphur were similar to personal concentrations after exclusion of ETS. When repeated measurements were taken into account, there was a statistically significant association between personal and outdoor absorbance when adjusting for ETS (slope 0.66, p<0.001), but for PM 2.5 the association was weaker (slope 0.51, p=0.066). Adjustment for ETS had little effect on the respective association of S (slope 0.69, p<0.001).Our results suggest that outdoor measurements of absorbance and sulphur can be used to estimate both the daily variation and levels of personal exposures also in Southern European countries, especially when exposure to ETS has been taken into account. For PM 2.5, indoor sources need to be carefully considered. 相似文献
3.
Methylcyclopentadienyl manganese tricarbonyl (MMT) is a manganese-based gasoline additive used to enhance automobile performance. MMT has been used in Canadian gasoline for about 20 yr. Because of the potential for increased levels of Mn in particulate matter resulting from automotive exhausts, a large-scale population-based exposure study (∼1000 participant periods) was conducted in Toronto, Canada, to estimate the distribution of 3-day average personal exposures to particulate matter (PM 2.5 and PM 10) and Mn. A stratified, three-stage, two-phase probability, longitudinal sample design of the metropolitan population was employed. Residential indoor and outdoor, and ambient levels (at a fixed site and on a roof) of PM 2.5, PM 10, and Mn were also measured. Supplementary data on traffic counts, meteorology, MMT levels in gasoline, personal occupations, and activities (e.g. amount of vehicular usage) were collected. Overall precision (%RSD) for analysis of duplicate co-located samples ranged from 2.5 to 5.0% for particulate matter and 3.1 to 5.5% for Mn. The detection limits were 1.47 and 3.45 μg m -3 for the PM 10 and PM 2.5 fractions, respectively, and 5.50 and 1.83 ng m -3 for Mn in PM 10 and PM 2.5, respectively. These low detection limits permitted the reporting of concentrations for >98% of the samples. For PM 10, the personal particulate matter levels (median 48.5 μg m -3) were much higher than either indoor (23.1 μg m -3) or outdoor levels (23.6 μg m -3). The median levels for PM 2.5 for personal, indoor, and outdoor were 28.4, 15.4 and 13.2 μg m -3, respectively. The correlation between PM 2.5 personal exposures and indoor concentrations was high (0.79), while correlations between personal and the outdoor, fixed site and roof site were low (0.16–0.27). Indoor Mn concentration distributions (in PM 2.5 and PM 10), unlike particulate matter, exhibited much lower and less variable levels that the corresponding outdoor data. The median personal exposure was 8.0 ng m -3, compared with 4.7 and 8.6 ng m -3, respectively, for the indoor and outdoor distributions. The highest correlations occurred for personal vs indoor data (0.56) and for outdoor vs roof site data (0.66), and vs fixed site data (0.56). The concentration of Mn in particulate matter, expressed in ppm (w/w), revealed that the fixed site was the highest, followed by the roof site, outdoor, indoor, and personal. The personal and indoor data showed a statistically significant correlation (0.68) while all other correlations between personal or indoor data and outdoor or fixed-site data were quite small. The low correlations of personal and indoor levels with outdoor levels suggest that different sources in the indoor and outdoor microenvironments produce particle matter with dissimilar composition. The correlation results indicate that neither the roof- nor fixed-site concentrations can adequately predict personal particulate matter or Mn exposures. 相似文献
4.
ABSTRACT To evaluate the validity of fixed-site fine particle levels as exposure surrogates in air pollution epidemiology, we considered four indicator groups: (1) PM 25 total mass concentrations, (2) sulfur and potassium for regional air pollution, (3) lead and bromine for traffic-related particles, and (4) calcium for crustal particles. Using data from the European EXPOLIS (Air Pollution Exposure Distribution within Adult Urban Populations in Europe) study, we assessed the associations between 48-hr personal exposures and home outdoor levels of the indicators. Furthermore, within-city variability of fine particle levels was evaluated. Personal exposures to PM 2.5 mass were not correlated to corresponding home outdoor levels (n = 44, r S (S) =r o v ' Spearman (Sp) 0.07). In the group reporting neither relevant indoor sources nor relevant activities, personal exposures and home outdoor levels of sulfur were highly correlated (n = 40, r Sp = 0.85). In contrast, the associations were weaker for traffic (Pb: n = 44, r Sp = 0.53; Br: n = 44, r Sp = 0.21) and crustal (Ca: n = 44, rSp = 0.12) indicators. This contrast is consistent with spatially homogeneous regional pollution and higher spatial variability of traffic and crustal indicators observed in Basel, Switzerland. We conclude that for regional air pollution, fixed-site fine particle levels are valid exposure surrogates. For source-specific exposures, however, fixed-site data are probably not the optimal measure. Still, in air pollution epidemiology, ambient PM 2.5 levels may be more appropriate exposure estimates than total personal PM 2.5 exposure, since the latter reflects a mixture of indoor and outdoor sources. 相似文献
5.
The functional group (FG) composition of urban residential outdoor, indoor, and personal fine particle (PM 2.5) samples is presented and used to provide insights relevant to organic PM 2.5 exposure. PM 2.5 samples (48 h) were collected during the Relationship of Indoor, Outdoor, and Personal Air (RIOPA) study at 219 non-smoking homes (once or twice) in Los Angeles County, CA, Elizabeth, NJ, and Houston, TX. Fourier transform infrared (FTIR) spectra of PM 2.5 samples were collected, and FG absorbances were quantified by partial least squares (PLS) regression, a multivariate calibration method.There is growing evidence in the literature that a large majority of indoor-generated PM 2.5 is organic. The current research suggests that indoor-generated PM 2.5 is enriched in aliphatic carbon–hydrogen (CH) FGs relative to ambient outdoor PM 2.5. Indoor-generated CH exceeded outdoor-generated CH in 144 of the 167 homes for which indoor or outdoor CH was measurable; estimated indoor emission rates are provided. The strong presence of aliphatic CH FGs in indoor PM 2.5 makes particulate organic matter substantially less polar indoors and in personal exposures than outdoors. This is a substantial new finding. Based on the quantified FGs, the average organic molecular weight (OM) per carbon weight (OC), a measure of the degree of oxygenation of organic PM, is in the range of 1.7–2.6 for outdoor samples and 1.3–1.7 for indoor and personal samples. Polarity or degree of oxygenation effects particle deposition in exposure environments and in the respiratory system. 相似文献
7.
Behavioral and environmental determinants of PM 2.5 personal exposures were analyzed for 201 randomly selected adult participants (25–55 years old) of the EXPOLIS study in Helsinki, Finland. Personal exposure concentrations were higher than respective residential outdoor, residential indoor and workplace indoor concentrations for both smokers and non-smokers. Mean personal exposure concentrations of active smokers (31.0±31.4 μg m −3) were almost double those of participants exposed to environmental tobacco smoke (ETS) (16.6±11.8 μg m −3) and three times those of participants not exposed to tobacco smoke (9.9±6.2 μg m −3). Mean indoor concentrations of PM 2.5 when a member of the household smoked indoors (20.8±23.9 μg m −3) were approximately 2.5 times the concentrations of PM 2.5 when no smoking was reported (8.2±5.2 μg m −3). Interestingly, however, both mean (8.2 μg m −3) and median (6.9 μg m −3) residential indoor concentrations for non-ETS exposed participants were lower than residential outdoor concentrations (9.5 and 7.3 μg m −3, respectively). In simple linear regression models residential indoor concentrations were the best predictors of personal exposure concentrations. Correlations ( r2) between PM 2.5 personal exposure concentrations of all participants, both smoking and non-smoking, and residential indoor, workplace indoor, residential outdoor and ambient fixed site concentrations were 0.53, 0.38, 0.17 and 0.16, respectively. Predictors for personal exposure concentrations of non-ETS exposed participants identified in multiple regression were residential indoor concentrations, workplace concentrations and traffic density in the nearest street from home, which accounted for 77% of the variance. Subsequently, step-wise regression not including residential and workplace indoor concentrations as input (as these are frequently not available), identified ambient PM 2.5 concentration and home location, as predictors of personal exposure, accounting for 47% of the variance. Ambient fixed site PM 2.5 concentrations were closely related to residential outdoor concentrations ( r2=0.9, p=0.000) and PM 2.5 personal exposure concentrations were higher in summer than during other seasons. Personal exposure concentrations were significantly ( p=0.040) higher for individuals living downtown compared with individuals in suburban family homes. Further analysis will focus on comparisons of determinants between Helsinki and other EXPOLIS centers. 相似文献
8.
ABSTRACT We measured particulate matter (PM 2.5 and PM 10) exposures, home temperature, arterial blood oxygen saturation, blood pressure, and lung function in 30 volunteer Los Angeles area residents during four-day intervals. Continuous Holter electrocardiograms were recorded in a subgroup on the first two days. Subjects recorded symptoms and time-activity patterns in diaries during monitoring, and during a reference period one week earlier/later. All subjects had severe chronic obstructive pulmonary disease. PM 10 (24-hr mean) at monitoring stations near subjects’ homes averaged 33 μg/m 3, and ranged from 9 to 84 μpg/m 3. In longitudinal analyses, day-to-day changes in PM 2.5 and PM 10 outside subjects’ homes significantly tracked concurrent station PM10 (r 2 = 0.22 and 0.44, respectively). Indoor and personal concentrations were less related to station readings (r 2 ≤ 0.1), but tracked each other (r 2 ≥ 0.4). In-home temperatures tracked outdoor temperatures more for lows (r 2 = 0.27) than for highs (r 2 = 0.10). These longitudinal relationships of subject-oriented and station PM measurements were generally similar to cross-sectional relationships observed previously in similar subjects. Among health measurements, only blood pressure showed reasonably consistent unfavorable longitudinal associations with particulates, more with station or outdoor PM than with indoor or personal PM. 相似文献
9.
ABSTRACT The time-series correlation between ambient levels, indoor levels, and personal exposure to PM 2.5 was assessed in panels of elderly subjects with cardiovascular disease in Amsterdam, the Netherlands, and Helsinki, Finland. Subjects were followed for 6 months with biweekly clinical visits. Each subject's indoor and personal exposure to PM 2.5 was measured biweekly, during the 24-hr period preceding the clinical visits. Outdoor PM 2.5 concentrations were measured at fixed sites. The absorption coefficients of all PM 2.5 filters were measured as a marker for elemental carbon (EC). Regression analyses were conducted for each subject separately, and the distribution of the individual regression and correlation coefficients was investigated. Personal, indoor, and ambient concentrations were highly correlated within subjects over time. Median Pearson's R between personal and outdoor PM 2.5 was 0.79 in Amsterdam and 0.76 in Helsinki. For absorption, these values were 0.93 and 0.81 for Amsterdam and Helsinki, respectively. The findings of this study provide further support for using fixed-site measurements as a measure of exposure to PM 2.5 in epidemiological time-series studies. 相似文献
10.
PM 2.5 (particulate matter with an aerodynamic diameter <2.5 μm) samples were collected in the indoor environments of 15 urban homes and their adjacent outdoor environments in Alexandria, Egypt, during the spring time. Indoor and outdoor carbon dioxide (CO 2) levels were also measured concurrently. The results showed that indoor and outdoor PM 2.5 concentrations in the 15 sites, with daily averages of 45.5 ± 11.1 and 47.3 ± 12.9 µg/m 3, respectively, were significantly higher than the ambient 24-hr PM 2.5 standard of 35 µg/m 3 recommended by the U.S. Environmental Protection Agency (EPA). The indoor PM 2.5 and CO 2 levels were correlated with the corresponding outdoor levels, demonstrating that outdoor convection and infiltration could lead to direct transportation indoors. Ventilation rates were also measured in the selected residences and ranged from 1.6 to 4.5 hr ?1 with median value of 3.3 hr ?1. The indoor/outdoor (I/O) ratios of the monitored homes varied from 0.73 to 1.65 with average value of 0.99 ± 0.26 for PM 2.5, whereas those for CO 2 ranged from 1.13 to 1.66 with average value of 1.41 ± 0.15. Indoor sources and personal activities, including smoking and cooking, were found to significantly influence indoor levels.Implications: Few studies on indoor air quality were carried out in Egypt, and the scarce data resulted from such studies do not allow accurate assessment of the current situation to take necessary preventive actions. The current research investigates indoor levels of PM2.5 and CO2 in a number of homes located in the city of Alexandria as well as the potential contribution from both indoor and outdoor sources. The study draws attention of policymakers to the importance of the establishment of national indoor air quality standards to protect human health and control air pollution in different indoor environments. 相似文献
11.
Abstract The impact of outdoor and indoor pollution sources on indoor air quality in Santiago, Chile was investigated. Toward this end, 16 homes were sampled in four sessions. Each session included an outdoor site and four homes using different unvented space heaters (electric or central heating, compressed natural gas, liquefied petroleum gas, and kerosene). Average outdoor fine particulate matter (PM 2.5) concentrations were very high (55.9 μg·m -3), and a large fraction of these particles penetrated indoors. PM 2.5 and several PM 2.5 components (including sulfate, elemental carbon, organic carbon, metals, and polycyclic aromatic hydrocarbons) were elevated in homes using kerosene heaters. Nitrogen dioxide (NO 2) and ultrafine particles (UFPs) were higher in homes with combustion heaters as compared with those with electric heaters or central heating. A regression model was used to assess the effect of heater use on continuous indoor PM 2.5 concentrations when windows were closed. The model found an impact only for kerosene heaters (45.8 μg m -3). 相似文献
12.
Indoor particulate matter samples were collected in 17 homes in an urban area in Alexandria during the summer season. During air measurement in all selected homes, parallel outdoor air samples were taken in the balconies of the domestic residences. It was found that the mean indoor PM 2.5 and PM 10 (particulate matter with an aerodynamic diameter ≤2.5 and ≤10 μm, respectively) concentrations were 53.5 ± 15.2 and 77.2 ± 15.1 µg/m 3, respectively. The corresponding mean outdoor levels were 66.2 ± 16.5 and 123.8 ± 32.1 µg/m 3, respectively. PM 2.5 concentrations accounted, on average, for 68.8 ± 12.8% of the total PM 10 concentrations indoors, whereas PM 2.5 contributed to 53.7 ± 4.9% of the total outdoor PM 10 concentrations. The median indoor/outdoor mass concentration (I/O) ratios were 0.81 (range: 0.43–1.45) and 0.65 (range: 0.4–1.07) for PM 2.5 and PM 10, respectively. Only four homes were found with I/O ratios above 1, indicating significant contribution from indoor sources. Poor correlation was seen between the indoor PM 10 and PM 2.5 levels and the corresponding outdoor concentrations. PM 10 levels were significantly correlated with PM 2.5 loadings indoors and outdoors and this might be related to PM 10 and PM 2.5 originating from similar particulate matter emission sources. Smoking, cooking using gas stoves, and cleaning were the major indoor sources contributed to elevated indoor levels of PM 10 and PM 2.5. Implications: The current study presents results of the first PM 2.5 and PM 10 study in homes located in the city of Alexandria, Egypt. Scarce data are available on indoor air quality in Egypt. Poor correlation was seen between the indoor and outdoor particulate matter concentrations. Indoor sources such as smoking, cooking, and cleaning were found to be the major contributors to elevated indoor levels of PM 10 and PM 2.5. 相似文献
13.
Metropolitan residents are concerned about their exposure to airborne pollutants. But establishing these exposures is challenging. A compact personal exposure kit (PEK) was developed to evaluate personal integrated exposure (PIE) from time-resolved data to particulate matter with aerodynamic diameter less than 2.5 μm (PM 2.5) in five microenvironments, including office, home, commuting, other indoor activities (other than home and office), and outdoor activities experienced both on weekdays and weekends. The study was conducted in Hong Kong. The PEK measured PM 2.5, reported location and several other factors, stored collected data, as well as reported the data back to the investigators using global system for mobile communication (GSM) telemetry. Generally, PM 2.5 concentrations in office microenvironment were found to be the smallest (13.0 μg/m 3), whereas the largest PM 2.5 concentration microenvironments were experienced during outdoor activities (54.4 μg/m 3). Participants spent more than 85% of their time indoors, including in offices, homes, and other public indoor venues. On average, 42% and 81% of the time were spent in homes, which contributed 52% and 79% of PIE (during weekdays and weekends, respectively), suggesting that improvement of air quality in homes may reduce overall exposures and indicating the need for actions to mitigate possible public health burdens in Hong Kong. This study also found that various indoor/outdoor microenvironments experienced by urban office workers cannot be accurately represented by general urban air quality data reported from the regulatory monitoring. Such personalized air quality information, especially while in transit or in offices and homes, may provide improved information on population exposures to air pollution. Implications: A newly developed personal exposure kit (PEK) was used to monitor PM2.5 exposure of metropolitan citizens in their daily life. Different microenvironments and time durations caused various personal integrated exposure (PIE). The stationary monitoring method for PIE was also compared and evaluated with PEK. Positive protection actions can be taken after understanding the major contribution to PM2.5 exposure. 相似文献
14.
Many individuals work outdoors in the formal and informal economy of the large urban areas in developing countries, where they are potentially exposed for long periods to high concentrations of ambient airborne particulate matter (PM). This study describes the personal exposures to PM of 2.5 μm aerodynamic diameter and smaller (PM 2.5) for a sample of outdoor and indoor workers in two cities, Mexico City and Puebla, in central Mexico.Thirty-six workers in Mexico City and 17 in Puebla were studied. Thirty were outdoor workers (i.e., taxi and bus drivers, street vendors, and vehicle inspectors) and 23 were indoor (office) workers. Their personal exposures to PM 2.5 were monitored for a mean 19-h period. In Mexico City, the street vendors and taxi drivers overall exposures were significantly higher than indoor workers were. In Puebla, bus drivers had a higher overall exposure than vehicle inspectors or indoor workers. Most of the exposures were above the 65 μg m −3 24-h Mexican standard.In Mexico City, exposures to Si, Ti, Cr, Mn, Fe, Ni, Cu, Mo and Cd were higher for outdoor than for indoor workers. In Puebla, exposures to Si, S, K, Ca, Ti, V, Mn, and Zn also were higher for outdoor workers. In Mexico City outdoor workers exposures to Cu, Pb, Cr, Se and Mo were 4 or more times higher than for Puebla outdoor workers, while Puebla outdoor workers’ exposures to V, Si, Fe and Ca were 3 or more times higher than Mexico City outdoor workers.These results suggest that for these outdoor workers the elevated local ambient air PM concentrations and an extended period spent outside are more important contributors to total exposures than indoor concentrations. These workers could be at particular risk of increased morbidity and mortality associated with ambient PM. 相似文献
15.
Continued development of personal air pollution monitors is rapidly improving government and research capabilities for data collection. In this study, we tested the feasibility of using GPS-enabled personal exposure monitors to collect personal exposure readings and short-term daily PM 2.5 measures at 15 fixed locations throughout a community. The goals were to determine the accuracy of fixed-location monitoring for approximating individual exposures compared to a centralized outdoor air pollution monitor, and to test the utility of two different personal monitors, the RTI MicroPEM V3.2 and TSI SidePak AM510. For personal samples, 24-hr mean PM 2.5 concentrations were 6.93 μg/m 3 (stderr = 0.15) and 8.47 μg/m 3 (stderr = 0.10) for the MicroPEM and SidePak, respectively. Based on time–activity patterns from participant journals, exposures were highest while participants were outdoors (MicroPEM = 7.61 µg/m 3, stderr = 1.08, SidePak = 11.85 µg/m 3, stderr = 0.83) or in restaurants (MicroPEM = 7.48 µg/m 3, stderr = 0.39, SidePak = 24.93 µg/m 3, stderr = 0.82), and lowest when participants were exercising indoors (MicroPEM = 4.78 µg/m 3, stderr = 0.23, SidePak = 5.63 µg/m 3, stderr = 0.08). Mean PM 2.5 at the 15 fixed locations, as measured by the SidePak, ranged from 4.71 µg/m 3 (stderr = 0.23) to 12.38 µg/m 3 (stderr = 0.45). By comparison, mean 24-h PM 2.5 measured at the centralized outdoor monitor ranged from 2.7 to 6.7 µg/m 3 during the study period. The range of average PM 2.5 exposure levels estimated for each participant using the interpolated fixed-location data was 2.83 to 19.26 µg/m 3 (mean = 8.3, stderr = 1.4). These estimated levels were compared with average exposure from personal samples. The fixed-location monitoring strategy was useful in identifying high air pollution microclimates throughout the county. For 7 of 10 subjects, the fixed-location monitoring strategy more closely approximated individuals’ 24-hr breathing zone exposures than did the centralized outdoor monitor. Highlights are: Individual PM 2.5 exposure levels vary extensively by activity, location and time of day; fixed-location sampling more closely approximated individual exposures than a centralized outdoor monitor; and small, personal exposure monitors provide added utility for individuals, researchers, and public health professionals seeking to more accurately identify air pollution microclimates. Implications: Personal air pollution monitoring technology is advancing rapidly. Currently, personal monitors are primarily used in research settings, but could they also support government networks of centralized outdoor monitors? In this study, we found differences in performance and practicality for two personal monitors in different monitoring scenarios. We also found that personal monitors used to collect outdoor area samples were effective at finding pollution microclimates, and more closely approximated actual individual exposure than a central monitor. Though more research is needed, there is strong potential that personal exposure monitors can improve existing monitoring networks. 相似文献
16.
Effects of physical/environmental factors on fine particle (PM 2.5) exposure, outdoor-to-indoor transport and air exchange rate ( AER) were examined. The fraction of ambient PM 2.5 found indoors ( FINF) and the fraction to which people are exposed ( α) modify personal exposure to ambient PM 2.5. Because FINF, α, and AER are infrequently measured, some have used air conditioning (AC) as a modifier of ambient PM 2.5 exposure. We found no single variable that was a good predictor of AER. About 50% and 40% of the variation in FINF and α, respectively, was explained by AER and other activity variables. AER alone explained 36% and 24% of the variations in FINF and α, respectively. Each other predictor, including Central AC Operation, accounted for less than 4% of the variation. This highlights the importance of AER measurements to predict FINF and α. Evidence presented suggests that outdoor temperature and home ventilation features affect particle losses as well as AER, and the effects differ.Total personal exposures to PM 2.5 mass/species were reconstructed using personal activity and microenvironmental methods, and compared to direct personal measurement. Outdoor concentration was the dominant predictor of (partial R2 = 30–70%) and the largest contributor to (20–90%) indoor and personal exposures for PM 2.5 mass and most species. Several activities had a dramatic impact on personal PM 2.5 mass/species exposures for the few study participants exposed to or engaged in them, including smoking and woodworking. Incorporating personal activities (in addition to outdoor PM 2.5) improved the predictive power of the personal activity model for PM 2.5 mass/species; more detailed information about personal activities and indoor sources is needed for further improvement (especially for Ca, K, OC). Adequate accounting for particle penetration and persistence indoors and for exposure to non-ambient sources could potentially increase the power of epidemiological analyses linking health effects to particulate exposures. 相似文献
17.
Outdoor, indoor and personal PM 2.5 measurements were made in a population of nonsmoking adults from three communities in the Minneapolis–St. Paul metropolitan area between April and November 1999. Thirty-two healthy adult subjects (23 females, 9 males; mean age 42±10, range: 24–64 yr) were monitored for 2–15 days during the spring, summer, and fall monitoring seasons. Twenty-four hour average gravimetric PM 2.5 samples were collected using a federal reference monitor (Anderson RAAS2.5-300) located at outdoor (O) central sites in the Battle Creek (BCK), East St. Paul (ESP) and Phillips (PHI) communities. Concurrent 24-h average indoor (I) and personal (P), and a limited number of outdoor-at-home (O@H) samples were collected using inertial impactors (PEM™ Model 200, MSP, Inc). The O (geometric mean {GM}=8.6; n=271; range: 1.0–41 μg/m 3) were lower than I concentrations (GM=10.7; n=294; range 1.3–131 μg/m 3), which were lower than P concentrations (GM=19.0; n=332; range 2.2–298 μg/m 3). Correlation coefficients between O concentrations in the three communities were high and measured GM O levels in BCK were significantly lower than ESP, most likely because of local sources, but GM concentrations in PHI were not significantly different from BCK or ESP. On days with paired samples ( n=29), O concentrations were significantly lower (mean difference 2.9 μg/m 3; p=0.026) than O@H measurements (GM=11.3; range: 3.5–33.8 μg/m 3), likely due to local sources in communities. Observed I and P concentrations were more variable, probably because of residential central air conditioning and hours of household ventilation for I and P, and occupational and environmental tobacco smoke exposures outside the residence for P. Across all individuals and days the median PM 2.5 “personal cloud” was 5.7 μg/m 3, but the mean of the average for each participant was 15.7 μg/m 3, with very low values in participants who did not work outside the home and much higher values in subjects with active lifestyles. Across all households and individuals the correlation between P and O concentrations was not significant, but the overall I–O correlation (0.27) and P–I correlation (0.51) were significant ( p<0.05). Relatively little spatial variability was observed in O PM 2.5 concentrations across the three communities compared to the variability associated with I and P samples, and the measured O levels were relatively low compared to other large metropolitan areas in the United States. 相似文献
18.
The objective of this study was to estimate the residential infiltration factor (Finf) of fine particulate matter (PM 2.5) and to develop models to predict PM 2.5 Finf in Beijing. Eighty-eight paired indoor–outdoor PM 2.5 samples were collected by Teflon filters for seven consecutive days during both non-heating and heating seasons (from a total of 55 families between August, 2013 and February, 2014). The mass concentrations of PM 2.5 were measured by gravimetric method, and elemental concentrations of sulfur in filter deposits were determined by energy-dispersive x-ray fluorescence (ED-XRF) spectrometry. PM 2.5 Finf was estimated as the indoor/outdoor sulfur ratio. Multiple linear regression was used to construct Finf predicting models. The residential PM 2.5 Finf in non-heating season (0.70 ± 0.21, median = 0.78, n = 43) was significantly greater than in heating season (0.54 ± 0.18, median = 0.52, n = 45, p < 0.001). Outdoor temperature, window width, frequency of window opening, and air conditioner use were the most important predictors during non-heating season, which could explain 57% variations across residences, while the outdoor temperature was the only predictor identified in heating season, which could explain 18% variations across residences. The substantial variations of PM 2.5 Finf between seasons and among residences found in this study highlight the importance of incorporating Finf into exposure assessment in epidemiological studies of air pollution and human health in Beijing. The Finf predicting models developed in this study hold promise for incorporating PM 2.5 Finf into large epidemiology studies, thereby reducing exposure misclassification. Implications: Failure to consider the differences between indoor and outdoor PM2.5 may contribute to exposure misclassification in epidemiological studies estimating exposure from a central site measurement. This study was conducted in Beijing to investigate residential PM2.5 infiltration factor and to develop a localized predictive model in both nonheating and heating seasons. High variations of PM2.5 infiltration factor between the two seasons and across homes within each season were found, highlighting the importance of including infiltration factor in the assessment of exposure to PM2.5 of outdoor origin in epidemiological studies. Localized predictive models for PM2.5 infiltration factor were also developed. 相似文献
19.
PM 2.5 sampling was conducted at a curbside location in Delhi city for summer and winter seasons, to evaluate the effect of PM 2.5 and its chemical components on the visibility impairment. The PM 2.5 concentrations were observed to be higher than the National Ambient Air Quality Standards (NAAQS), indicating poor air quality. The chemical constituents of PM 2.5 (the water-soluble ionic species SO 42-, NO 3?, Cl ?, and NH 4+, and carbonaceous species: organic carbon, elemental carbon) were analyzed to study their impact on visibility impairment by reconstructing the light extinction coefficient, b ext. The visibility was found to be negatively correlated with PM 2.5 and its components. The reconstructed b ext showed that organic matter was the largest contributor to b ext in both the seasons which may be attributed to combustion sources. In summer season, it was followed by elemental carbon and ammonium sulfate; however, in winter, major contributions were from ammonium nitrate and elemental carbon. Higher elemental carbon in both seasons may be attributed to traffic sources, while lower concentrations of nitrate during summer, may be attributed to volatility because of higher atmospheric temperatures. Implications: The chemical constituents of PM 2.5 that majorly effect the visibility impairment are organic matter and elemental carbon, both of which are products of combustion processes. Secondary formations that lead to ammonium sulfate and ammonium nitrate production also impair the visibility. 相似文献
20.
Abstract Particle infiltration is a key determinant of the indoor concentrations of ambient particles. Few studies have examined the influence of particle composition on infiltration, particularly in areas with high concentrations of volatile particles, such as ammonium nitrate (NH 4NO 3). A comprehensive indoor monitoring study was conducted in 17 Los Angeles–area homes. As part of this study, indoor/outdoor concentration ratios during overnight (nonindoor source) periods were used to estimate the fraction of ambient particles remaining airborne indoors, or the particle infiltration factor (F INF), for fine particles (PM 2.5), its nonvolatile (i.e., black carbon [BC]) and volatile (i.e., nitrate [NO 3 ?]) components, and particle sizes ranging between 0.02 and 10 μm. F INF was highest for BC (median = 0.84) and lowest for NO 3 ? (median = 0.18). The low F INF for NO 3 ? was likely because of volatilization of NO 3 ? particles once indoors, in addition to depositional losses upon building entry. The F INF for PM 2.5 (median = 0.48) fell between those for BC and NO 3 ?, reflecting the contributions of both particle components to PM 2.5. F INF varied with particle size, air-exchange rate, and outdoor NO 3 ? concentrations. The F INF for particles between 0.7 and 2 μm in size was considerably lower during periods of high as compared with low outdoor NO 3 ? concentrations, suggesting that outdoor NO 3 ? particles were of this size. This study demonstrates that infiltration of PM 2.5 varies by particle component and is lowest for volatile species, such as NH 4NO 3. Our results suggest that volatile particle components may influence the ability for outdoor PM concentrations to represent indoor and, thus, personal exposures to particles of ambient origin, because volatilization of these particles causes the composition of PM 2.5 to differ indoors and outdoors. Consequently, particle composition likely influences observed epidemiologic relationships based on outdoor PM concentrations, especially in areas with high concentrations of NH 4NO 3 and other volatile particles. 相似文献
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