Ambient Levels Of PM2 Research Articles

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.

99/02807 In-stack condensible particulate matter measurement and permitting issues

Based on the results of recent epidemiological studies and assessments of the causes of visibility degradation, EPA is proposing to regulate PM2.5 emissions. PM can be classified as either filterable or condensible PM. Condensible PM includes sulfates, such as sulfuric acid. Sulfates typically account for at least half of the total dry fine PM mass in the atmosphere. Power plant SO{sub x}-based emissions make a significant contribution to ambient fine PM levels in the eastern US. Although much of this mass is derived from secondary chemical reactions in the atmosphere, a portion of this sulfate is emitted directly from stacks as condensible PM. The potential condensible PM fraction associated with coal-burning boiler emissions is somewhat uncertain. The characterization of PM emissions from these sources has been, until recently, based on in-stack filterable PM measurements only. To determine the relative magnitude of condensible PM emissions and better understand condensible PM measurement issues, a review and analysis of actual EPA Method 202 results and state-developed hybrid condensible PM methods were conducted. A review of available Method 202 results for several coal-burning boilers showed that the condensible PM, on average, comprises 60% of the total PM10. A review of recent results for state-developedmore » measurement methods for condensible PM for numerous coal-burning boilers indicated that condensible PM accounted for, on average, approximately 49% of total PM. Caution should be exercised in the use of these results because of the seemingly unresolved issue of artifact formation, which may bias the Method 202 and state-developed methods results on the high side. Condensible PM10 measurement results and issues, and potential ramifications of including condensible PM10 emissions in the PSD permit review process are discussed. Selected power plants in Maryland are discussed as examples.« less

Fetal Growth and Maternal Exposure to Particulate Matter during Pregnancy

Prior studies reported an association between ambient air concentrations of total suspended particles and SO2 during pregnancy and adverse pregnancy outcomes. We examined the possible impact of particulate matter up to 10 microm (PM10) and up to 2.5 microm (PM2. 5) in size on intrauterine growth retardation (IUGR) risk in a highly polluted area of Northern Bohemia (Teplice District). The study group includes all singleton full-term births of European origin over a 2-year period in the Teplice District. Information on reproductive history, health, and lifestyle was obtained from maternal questionnaires. The mean concentrations of pollutants for each month of gestation were calculated using continuous monitoring data. Three intervals (low, medium, and high) were constructed for each pollutant (tertiles). Odds ratios (ORs) for IUGR for PM10 and PM2.5 levels were generated using logistic regression for each month of gestation after adjustment for potential confounding factors. Adjusted ORs for IUGR related to ambient PM10 levels in the first gestational month increased along the concentration intervals: medium 1.62 [95% confidence interval (CI), 1.07-2.46], high 2.64 (CI, 1.48-4.71). ORs for PM2.5 were 1.26 (CI, 0.81-1.95) and 2.11 (CI, 1. 20-3.70), respectively. No other associations of IUGR risk with particulate matter were found. Influence of particles or other associated air pollutants on fetal growth in early gestation is one of several possible explanations of these results. Timing of this effect is compatible with a current hypothesis of IUGR pathogenesis. Seasonal factors, one of the other possible explanations, is less probable. More investigation is required to examine these findings and alternative explanations.

Particulate matter and manganese exposures in Toronto, Canada

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.

Effects of Building Ventilation Types and Human Activity Patterns on Indoor PM10Levels

Abstract Indoor and ambient PM10 levels at two Salt Lake hospitals were examined during the months of January through May 1995. In addition to the PM10 data, the level of human activity was estimated at each of the six indoor sampler sites at each hospital. At each hospital two different air filtration environments were sampled. At hospital A, bag filtration (BF) and high efficiency particulate air (HEPA) systems were sampled, and at hospital C, low efficiency (LE) and BF were sampled. The average ambient PM10 levels at each hospital were significantly different (p < 0.05). At both hospitals the average indoor PM10 for each air filtration system was compared with the ambient PM10 level. In all but one case the indoor PM10 was significantly less than the ambient PM10 (hospital A = 18.7 μg/m3/24 h and hospital C = 26 μg/m3/24 h, p < 0.05). Within an air filtration system some sampler sites had significantly higher average PM10 than did the other sampler sites. The effectiveness of BF versus HEPA and LE vers...

Risk assessment for combustion products of the gasoline additive MMT in Canada

Methylcyclopentadienyl manganese tricarbonyl (MMT) has been used as an octane enhancer in Canadian gasoline since 1976. The main potential health concern is from manganese oxides produced on combustion (mainly Mn3O4), given the known neurotoxicity of chronic inhalation of manganese (Mn) dust from mining and industrial use. Relevant epidemiological studies of occupational exposure to respirable Mn are briefly reviewed; an ambient air reference value of 0.1 μg Mn/m3, and associated inhalation tolerable daily intake (TDI) and tolerable daily uptake (TDU) of 0.035 and 0.021 μg/kg b.w./day are derived. Ambient levels of PM2.5 (respirable) Mn in Canadian cities have remained unchanged or have decreased between 1986 and 1992, and do not reflect large changes in MMT usage during that time. Ambient levels of PM10 Mn in Canadian cities in 1992 were ≤0.025 μg Mn/m3. Mean, 90th and 98th percentiles of PM10 Mn inhalation uptake based on ambient monitoring data from high traffic areas and from estimates of personal exposure are below the inhalation uptake criterion. An assessment of exposure from air, food, water and soil revealed that <1% of total daily Mn uptake is derived from inhalation for all age groups. Therefore, based on current information, Mn derived from the combustion of MMT-containing gasoline is unlikely to represent a significant health risk to Canadians.

Health effects of outdoor air pollution. Committee of the Environmental and Occupational Health Assembly of the American Thoracic Society.

Particles, SOx, and acid aerosols are a complex group of distinct pollutants that have common sources and usually covary in concentration. During the past two decades, the chemical characteristics and the geographic distribution of sulfur oxide and particulate pollution have been altered by control strategies, specifically taller stacks for power plants, put in place in response to air pollution regulations adopted in the early 1970s. While the increasing stack heights have lowered local ambient levels, the residence time of SOx and particles in the air have been increased, thereby promoting transformation to various particulate sulfate compounds, including acidic sulfates. These sulfate particles constitute a large fraction of the total mass of smaller particles (< 3 microns in aerodynamic diameter). Epidemiologic studies have consistently provided evidence of adverse health effects of these air pollutants. Particulate and SO2 pollution were strongly implicated in the acute morbidity and mortality associated with the severe pollution episodes in Donora (Pennsylvania), London, and New York in the 1940s, 1950s, and 1960s. There is new evidence that even current ambient levels of PM10 (30 to 150 micrograms/m3) are associated with increases in daily cardiorespiratory mortality and in total mortality, excluding accidental and suicide deaths. These associations have been shown in many different communities, as widely different in particle composition and climate as Philadelphia, St. Louis, Utah Valley, and Santa Clara County, California. It has recently been shown in a long-term prospective study of adults in the United States that chronic levels of higher PM10 pollution are associated with increased mortality after adjusting for several individual risk factors. Daily fluctuations in PM10 levels have also been shown to be related to acute respiratory hospital admissions in children, to school and kindergarten absences, to decrements in peak flow rates in normal children, and to increased medication use in children and adults with asthma. Although some epidemiologic studies suggest that acid aerosols are an important toxic component of PM10, other studies do not support this hypothesis. Dockery and Pope (408) recently reviewed the epidemiologic literature for adverse effects, assuming that reported associations can be attributed to acute particle mass exposures. Combined effects were estimated as percent increase in comparable measures of mortality and morbidity, associated with each 10 micrograms/m3 increase in daily mean PM10 exposure (Table 7). While total mortality increased by 1% for each 10 micrograms/m3 increase in PM10, respiratory mortality increased by 3.4% and cardiovascular mortality increased by 1.4%. Hospital admissions and emergency department visits increased approximately 1% for all respiratory complaints, and 2% to 3% for asthma. Exacerbation of asthma increased by about 3%, as did lower respiratory symptoms. Small decreases in lung function, approximately 0.1%, have also been observed. This review suggests that the epidemiologic studies of adverse morbidity measures are coherent with the mortality studies showing quantitatively similar adverse effects of acute exposures to particulate pollution. Despite these epidemiologic findings for acute and chronic adverse health effects from air pollution associated with relatively low levels of inhalable particles, there are no complementary data from toxicologic studies or from acute human exposures to similar levels of respirable particles. Thus, controlled human exposures to various particles, including H2SO4, at relevant levels (< 150 micrograms/m3) have not identified significant alterations in respiratory function in healthy individuals.(ABSTRACT TRUNCATED)

Effects of Air Pollution Episodes on Pulmonary Function and Respiratory Symptoms

In January 1985, a decline of primary school children's pulmonary function was observed during an air pollution episode. Ambient 24 hour average levels of SO2, TSP and RSP were in the range of 200-250 micrograms/m3. The response persisted for at least two weeks. In January 1987, again a decline of school children's pulmonary function was observed associated with an air pollution episode. Levels of TSP were about as elevated as in the 1985 episode. Two weeks after the episode, lung function levels were even lower than during the episode. In June 1987 a long term study was started to investigate potential effects of winter and summer air pollution episodes on pulmonary function and occurrence of acute respiratory symptoms of primary school children. An important issue for this study is the characterization of short term variation of lung function in absence of air pollution. Exposure is characterized by ambient levels of several gases (SO2, NO2, O3, HNO3), PM10, TSP and components of particulate matter (SO4(2-), NO3-, H-, NH4+). Sampling is being conducted on a daily basis to obtain a continuous exposure estimate. In the winter of 1987/1988, no air pollution episodes were observed. The study will continue through the winters of 1988/1989, and 1989/1990.