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1.
Purpose The concentrations of PM 10 mass, PM 2.5 mass and particle number were continuously measured for 18 months in urban background locations across Europe to determine the spatial and temporal variability of particulate matter. Methods Daily PM 10 and PM 2.5 samples were continuously collected from October 2002 to April 2004 in background areas in Helsinki, Athens, Amsterdam and Birmingham. Particle mass was determined using analytical microbalances with precision of 1 ??g. Pre- and post-reflectance measurements were taken using smoke-stain reflectometers. One-minute measurements of particle number were obtained using condensation particle counters. Results The 18-month mean PM 10 and PM 2.5 mass concentrations ranged from 15.4 ??g/m 3 in Helsinki to 56.7 ??g/m 3 in Athens and from 9.0 ??g/m 3 in Helsinki to 25.0 ??g/m 3 in Athens, respectively. Particle number concentrations ranged from 10,091 part/cm 3 in Helsinki to 24,180 part/cm 3 in Athens with highest levels being measured in winter. Fine particles accounted for more than 60% of PM 10 with the exception of Athens where PM 2.5 comprised 43% of PM 10. Higher PM mass and number concentrations were measured in winter as compared to summer in all urban areas at a significance level p?0.05. Conclusions Significant quantitative and qualitative differences for particle mass across the four urban areas in Europe were observed. These were due to strong local and regional characteristics of particulate pollution sources which contribute to the heterogeneity of health responses. In addition, these findings also bear on the ability of different countries to comply with existing directives and the effectiveness of mitigation policies. 相似文献
2.
Purpose Various publications indicate that the operation of laser printers and photocopiers may be associated with health effects due to the release of gaseous components and fine and ultrafine particles (UFP). However, only sparse studies are available that evaluate the possible exposure of office workers to printer emissions under real conditions. Therefore, the aim of our study was to assess the exposure of office workers to particulate matter released from laser printers and photocopiers. Methods Concentrations of fine particles and UFP were measured before, during, and after the operation of laser printing devices in 63 office rooms throughout Germany. Additionally, the particles were characterized by electron microscopy and energy-dispersive X-ray spectroscopy. Results A significant increase of fine particles and UFP was identified in ambient workplace air during and after the printing processes. Particle fractions between 0.23 and 20???m emitted by the office machines significantly affect particle mass concentrations while printing 500 pages, i.e., during the printing process, PM 0.23?C20, PM 2.5, and PM 10 concentrations increased in 43 out of the evaluated 62 office rooms investigated. Additionally, a significant increase was observed in submicrometer particles, with median particle number concentrations of 6,503 particles/cm 3 before and 18,060 particles/cm 3 during the printing process. Conclusions Our data indicate that laser printers and photocopiers could be a relevant source of fine particles and particularly UFP in office rooms. 相似文献
3.
Purpose This study presents a procedure to differentiate the local and remote sources of particulate-bound polycyclic aromatic hydrocarbons (PAHs). Methods Data were collected during an extended PM 2.5 sampling campaign (2009?C2010) carried out for 1?year in Venice-Mestre, Italy, at three stations with different emissive scenarios: urban, industrial, and semirural background. Diagnostic ratios and factor analysis were initially applied to point out the most probable sources. In a second step, the areal distribution of the identified sources was studied by applying the discriminant analysis on factor scores. Third, samples collected in days with similar atmospheric circulation patterns were grouped using a cluster analysis on wind data. Local contributions to PM 2.5 and PAHs were then assessed by interpreting cluster results with chemical data. Results Results evidenced that significantly lower levels of PM 2.5 and PAHs were found when faster winds changed air masses, whereas in presence of scarce ventilation, locally emitted pollutants were trapped and concentrations increased. This way, an estimation of pollutant loads due to local sources can be derived from data collected in days with similar wind patterns. Long-range contributions were detected by a cluster analysis on the air mass back-trajectories. Results revealed that PM 2.5 concentrations were relatively high when air masses had passed over the Po Valley. However, external sources do not significantly contribute to the PAHs load. Conclusions The proposed procedure can be applied to other environments with minor modifications, and the obtained information can be useful to design local and national air pollution control strategies. 相似文献
4.
Background PM 10 aerosol samples were simultaneously collected at two urban and one urban background sites in Fuzhou city during two sampling campaigns in summer and winter. PM 10 mass concentrations and chemical compositions were determined. Methods Water-soluble inorganic ions (Cl ?, NO 3 ? , SO 4 2? , NH 4 + , K +, Na +, Ca 2+, and Mg 2+), carbonaceous species (elemental carbon and organic carbon), and elements (Al, Si, Mg, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, and Pb) were detected using ion chromatography, thermal/optical reflectance, and proton-induced X-ray emission methods, respectively. Results PM 10 mass concentrations, as well as most of the chemical components, were significantly increased from urban background to urban sites, which were due to enhanced anthropogenic activities in urban areas. Elements, carbonaceous species, and most of the ions were more uniformly distributed at different types of sites in winter, whereas secondary ion SO 4 2? , NO 3 ? , and NH 4 + showed more evident urban-background contrast in this season. The chemical mass closure indicated that mineral dust, organic matters, and sulfate were the most abundant components in PM 10. The sum of individually measured components accounted for 86.9?C97.7% of the total measured PM 10 concentration, and the discrepancy was larger in urban area than in urban background area. Conclusion According to the principal component analysis?Cmultivariate linear regression model, mineral dust, secondary inorganic ions, sea salt, and motor vehicle were mainly responsible for the PM 10 particles in Fuzhou atmosphere, and contributed 19.9%, 53.3%, 21.3%, and 5.5% of PM 10, respectively. 相似文献
5.
Background Continuous monitoring of air quality is implemented by government institutions at fixed ambient sites. However, the correlation between fixed site measurements and exposure of individual persons to air contaminants is likely to be weak. Materials and methods We measured particulate matter both outdoors and indoors by following the spatial movement of individuals. Sixteen test persons took part and carried a measurement backpack for a 24-h period. The backpack was comprised of a Grimm Aerosol Spectrometer model 1.109, a GPS device, and a video camera for tracking of human behavior. The spectrometer provided information about particle numbers and mass in 32-size classes with a high temporal resolution of 6 s. Results The personal exposure of individuals during 24 h could significantly exceed the outdoor particulate matter (PM) 10 concentrations measured at the fixed sites. The average 24-h exposure of all test persons for PM 10 varied from 27 to 322 ??g m ?3. Environmental tobacco smoke and cooking emissions were among the main indoor sources for PM. The amount of particulate matter a test person was exposed to was highly dependent on the spatial behavior and the surrounding microenvironment conditions. Discussion Large-scale experiments including personal measurements might help to improve modeling approaches to approximate the actual exposure on a statistically sound basis. 相似文献
6.
This study integrated estimated oxidation ratio of sulfur (SOR) and oxidation ratio of nitrogen (NOR) with source-receptor modeling results to identify the effects of terrain and monsoons on ambient aerosols in an urban area (north basin) and a rural area (south basin) of the Taichung Basin. The estimated results indicate that the conversion of sulfur mainly occurs in fine particles (PM 2.5), whereas the conversion of nitrogen occurs in approximately equal quantities of PM 2.5 and coarse particles (PM 2.5–10). The results show a direct relationship for PM 2.5 between the modeling results with SOR and NOR. The high PM 2.5 SOR, NOR, and secondary aerosol values all occurred in the upwind area during both monsoons; this shows that the photochemical reaction and the terrain effect on the pollutant transmission were significant in the basin. Additionally, the urban heat island effect on the urban area and the valley effect on the rural area were significant. The results show that secondary aerosol in PM 2.5–10 contributed approximately 10 % during both monsoons, and the difference in the contribution from secondary aerosol between both areas was small. Vehicle exhaust emissions and wind-borne dust were two crucial PM 2.5–10 contributors during both monsoons; their average contributions in both areas were higher than 34 and 32 %, respectively. 相似文献
7.
ABSTRACT With the promulgation of a national PM 2.5 ambient air quality standard, it is important that PM 2.5 emissions inventories be developed as a tool for understanding the magnitude of potential PM2.5 violations. Current PM 10 inventories include only emissions of primary particulate matter (1 ï PM), whereas, based on ambient measurements, both PM 10 and PM2.5 emissions inventories will need to include sources of both 1 ï PM and secondary particulate matter (2 ï PM). Furthermore, the U. S. Environmental Protection Agency’s (EPA) current edition of AP-42 includes size distribution data for 1o PM that overestimate the PM 2.5 fraction of fugitive dust sources by at least a factor of 2 based on recent studies. This paper presents a PM 2.5 emissions inventory developed for the South Coast Air Basin (SCAB) that for the first time includes both 1 ï PM and 2 ï PM. The former is calculated by multiplying PM 10 emissions estimates by the PM 2.5/PM 10 ratios for different sources. The latter is calculated from estimated emission rates of gas-phase aerosol precursor and gas to aerosol conversion rates consistent with the measured chemical composition of ambient PM 2.5 concentrations observed in the SCAB. The major finding of this PM 2.5 emissions inventory is that the 2ï aerosol component is more than twice the 1ï aerosol component, which may result in widely different control strategies being required for fine PM and coarse PM. 相似文献
8.
This paper synthesizes data on aerosol (particulate matter, PM) physical and chemical characteristics, which were obtained over the past decade in aerosol research and monitoring activities at more than 60 natural background, rural, near-city, urban, and kerbside sites across Europe. The data include simultaneously measured PM 10 and/or PM 2.5 mass on the one hand, and aerosol particle number concentrations or PM chemistry on the other hand. The aerosol data presented in our previous works (Van Dingenen et al., 2004, Putaud et al., 2004) were updated and merged to those collected in the framework of the EU supported European Cooperation in the field of Scientific and Technical action COST633 ( Particulate matter: Properties related to health effects). A number of conclusions from our previous studies were confirmed. There is no single ratio between PM 2.5 and PM 10 mass concentrations valid for all sites, although fairly constant ratios ranging from 0.5 to 0.9 are observed at most individual sites. There is no general correlation between PM mass and particle number concentrations, although particle number concentrations increase with PM 2.5 levels at most sites. The main constituents of both PM 10 and PM 2.5 are generally organic matter, sulfate and nitrate. Mineral dust can also be a major constituent of PM 10 at kerbside sites and in Southern Europe. There is a clear decreasing gradient in SO 42? and NO 3? contribution to PM 10 when moving from rural to urban to kerbside sites. In contrast, the total carbon/PM 10 ratio increases from rural to kerbside sites. Some new conclusions were also drawn from this work: the ratio between ultrafine particle and total particle number concentration decreases with PM 2.5 concentration at all sites but one, and significant gradients in PM chemistry are observed when moving from Northwestern, to Southern to Central Europe. Compiling an even larger number of data sets would have further increased the significance of our conclusions, but collecting all the aerosol data sets obtained also through research projects remains a tedious task. 相似文献
9.
Exposure to ambient particulate matter (PM) is known as a significant risk factor for mortality and morbidity due to cardiorespiratory causes. Owing to increased interest in assessing personal and community exposures to PM, we evaluated the feasibility of employing a low-cost portable direct-reading instrument for measurement of ambient air PM exposure. A Dylos DC 1700 PM sensor was collocated with a Grimm 11-R in an urban residential area of Houston Texas. The 1-min averages of particle number concentrations for sizes between 0.5 and 2.5 µm (small size) and sizes larger than 2.5 µm (large size) from a DC 1700 were compared with the 1-min averages of PM 2.5 (aerodynamic size less than 2.5 µm) and coarse PM (aerodynamic size between 2.5 and 10 µm) concentrations from a Grimm 11-R. We used a linear regression equation to convert DC 1700 number concentrations to mass concentrations, utilizing measurements from the Grimm 11-R. The estimated average DC 1700 PM 2.5 concentration (13.2 ± 13.7 µg/m 3) was similar to the average measured Grimm 11-R PM 2.5 concentration (11.3 ± 15.1 µg/m 3). The overall correlation ( r2) for PM 2.5 between the DC 1700 and Grimm 11-R was 0.778. The estimated average coarse PM concentration from the DC 1700 (5.6 ± 12.1 µg/m 3) was also similar to that measured with the Grimm 11-R (4.8 ± 16.5 µg/m 3) with an r2 of 0.481. The effects of relative humidity and particle size on the association between the DC 1700 and the Grimm 11-R results were also examined. The calculated PM mass concentrations from the DC 1700 were close to those measured with the Grimm 11-R when relative humidity was less than 60% for both PM 2.5 and coarse PM. Particle size distribution was more important for the association of coarse PM between the DC 1700 and Grimm 11-R than it was for PM 2.5. Implications: The performance of a low-cost particulate matter (PM) sensor was evaluated in an urban residential area. Both PM2.5 and coarse PM (PM10-2.5) mass concentrations were estimated using a DC1700 PM sensor. The calculated PM mass concentrations from the number concentrations of DC 1700 were close to those measured with the Grimm 11-R when relative humidity was less than 60% for both PM2.5 and coarse PM. Particle size distribution was more important for the association of coarse PM between the DC 1700 and Grimm 11-R than it was for PM2.5. 相似文献
10.
This study used several real-time and filter-based aerosol instruments to measure PM 2.5 levels in a high-rise residential green building in the Northeastern US and compared performance of those instruments. PM 2.5 24-hr average concentrations were determined using a Personal Modular Impactor (PMI) with 2.5 µm cut (SKC Inc., Eighty Four, PA) and a direct reading pDR-1500 (Thermo Scientific, Franklin, MA) as well as its filter. 1-hr average PM 2.5 concentrations were measured in the same apartments with an Aerotrak Optical Particle Counter (OPC) (model 8220, TSI, Inc., Shoreview, MN) and a DustTrak DRX mass monitor (model 8534, TSI, Inc., Shoreview, MN). OPC and DRX measurements were compared with concurrent 1-hr mass concentration from the pDR-1500. The pDR-1500 direct reading showed approximately 40% higher particle mass concentration compared to its own filter (n = 41), and 25% higher PM 2.5 mass concentration compared to the PMI 2.5 filter. The pDR-1500 direct reading and PMI 2.5 in non-smoking homes (self-reported) were not significantly different (n = 10, R 2 = 0.937), while the difference between measurements for smoking homes was 44% (n = 31, R 2 = 0.773). Both OPC and DRX data had substantial and significant systematic and proportional biases compared with pDR-1500 readings. However, these methods were highly correlated: R 2 = 0.936 for OPC versus pDR-1500 reading and R 2 = 0.863 for DRX versus pDR-1500 reading. The data suggest that accuracy of aerosol mass concentrations from direct-reading instruments in indoor environments depends on the instrument, and that correction factors can be used to reduce biases of these real-time monitors in residential green buildings with similar aerosol properties. Implications: This study used several real-time and filter-based aerosol instruments to measure PM2.5 levels in a high-rise residential green building in the northeastern United States and compared performance of those instruments. The data show that while the use of real-time monitors is convenient for measurement of airborne PM at short time scales, the accuracy of those monitors depends on a particular instrument. Bias correction factors identified in this paper could provide guidance for other studies using direct-reading instruments to measure PM concentrations. 相似文献
11.
Numerous studies have reported a positive association between ambient fine particles and daily mortality, but little is known about the particle properties or environmental factors that may contribute to these effects. This study assessed potential modification of radon on PM 2.5 (particulate matter with an aerodynamic diameter <2.5 μm)-associated daily mortality in 108 U.S. cities using a two-stage statistical approach. First, city- and season-specific PM 2.5 mortality risks were estimated using over-dispersed Poisson regression models. These PM 2.5 effect estimates were then regressed against mean city-level residential radon concentrations to estimate overall PM 2.5 effects and potential modification by radon. Radon exposure estimates based on measured short-term basement concentrations and modeled long-term living-area concentrations were both assessed. Exposure to PM 2.5 was associated with total, cardiovascular, and respiratory mortality in both the spring and the fall. In addition, higher mean city-level radon concentrations increased PM 2.5-associated mortality in the spring and fall. For example, a 10 µg/m 3 increase in PM 2.5 in the spring at the 10th percentile of city-averaged short-term radon concentrations (21.1 Bq/m 3) was associated with a 1.92% increase in total mortality (95% CI: 1.29, 2.55), whereas the same PM 2.5 exposure at the 90th radon percentile (234.2 Bq/m 3) was associated with a 3.73% increase in total mortality (95% CI: 2.87, 4.59). Results were robust to adjustment for spatial confounders, including average planetary boundary height, population age, percent poverty and tobacco use. While additional research is necessary, this study suggests that radon enhances PM 2.5 mortality. This is of significant regulatory importance, as effective regulation should consider the increased risk for particle mortality in cities with higher radon levels. Implications: In this large national study, city-averaged indoor radon concentration was a significant effect modifier of PM2.5-associated total, cardiovascular, and respiratory mortality risk in the spring and fall. These results suggest that radon may enhance PM2.5-associated mortality. In addition, local radon concentrations partially explain the significant variability in PM2.5 effect estimates across U.S. cities, noted in this and previous studies. Although the concept of PM as a vector for radon progeny is feasible, additional research is needed on the noncancer health effects of radon and its potential interaction with PM. Future air quality regulations may need to consider the increased risk for particle mortality in cities with higher radon levels. 相似文献
12.
Under the National Ambient Air Quality Standards (NAAQS), put in place as a result of the Clean Air Amendments of 1990, three regions in the state of Utah are in violation of the NAAQS for PM 10 and PM 2.5 (Salt Lake County, Ogden City, and Utah County). These regions are susceptible to strong inversions that can persist for days to weeks. This meteorology, coupled with the metropolitan nature of these regions, contributes to its violation of the NAAQS for PM during the winter. During January–February 2009, 1-hr averaged concentrations of PM 10-2.5, PM 2.5, NO x, NO 2, NO, O 3, CO, and NH 3 were measured. Particulate-phase nitrate, nitrite, and sulfate and gas-phase HONO, HNO 3, and SO 2 were also measured on a 1-hr average basis. The results indicate that ammonium nitrate averages 40% of the total PM 2.5 mass in the absence of inversions and up to 69% during strong inversions. Also, the formation of ammonium nitrate is nitric acid limited. Overall, the lower boundary layer in the Salt Lake Valley appears to be oxidant and volatile organic carbon (VOC) limited with respect to ozone formation. The most effective way to reduce ammonium nitrate secondary particle formation during the inversions period is to reduce NO x emissions. However, a decrease in NO x will increase ozone concentrations. A better definition of the complete ozone isopleths would better inform this decision. Implications: Monitoring of air pollution constituents in Salt Lake City, UT, during periods in which PM2.5 concentrations exceeded the NAAQS, reveals that secondary aerosol formation for this region is NOx limited. Therefore, NOx emissions should be targeted in order to reduce secondary particle formation and PM2.5. Data also indicate that the highest concentrations of sulfur dioxide are associated with winds from the north-northwest, the location of several small refineries. 相似文献
13.
Scientists have effectively proved that vegetative environment buffers (VEBs) can be used for reducing dust emissions from livestock buildings, but they have seen fewer tests in poultry farms. A field research was conducted to assess the effectiveness of VEBs on reducing downwind transport of particulate matter (PM) from a ventilated poultry house in Changchun. Five plant species transferred from local area were used to establish five diverse VEBs and separately installed outside of the ventilation fans in summer 2017. The five plant species were Winged Euonymus (WE), Malus Spectabilis (MS), Padus Maackii (PAA), Acer Saccharum Marsh (ASM), and Padus Virginiana “Red Select Shrub” (PV_RSS). The mass concentrations of PM 2.5 and PM 10 (particulate matter with an aerodynamic diameter of 2.5 μm and 10 μm or less, respectively) were monitored at downwind and upwind sampling locations around the VEB. The results showed that with the presenting of VEBs, the particle concentrations at the downwind sampling point were significantly reduced compared with that at the upwind sampling point ( p < 0.05). Specifically, compared to the control test without VEB, the VEB with PV_RSS had the best PM concentration reduction rate (CRR) of 47.24%±4.33% and 41.13%±5.83% for PM 2.5 and PM 10, respectively. The rough surface of plant leaves may help intercept more PM, though it was also affected by other factors (such as the blade angle, the interaction with wind) needed to be further investigated. The VEB with PV_RSS, which presented the best capacity of CRR, selectively intercepted PM, mainly related to the elements of N, Na, Mg, P, S, and Cl. Implications: Five plant species, including WE, PAA, MS, ASM, and PV_RSS, were evaluated as VEBs to mitigate particulate emissions from outside of a ventilated poultry house in Changchun. They all significantly reduced particulate matter emissions. However, the PV_RSS presented the best capability of trapping fine and coarse particles: PM2.5 and PM10, respectively, while the PAA was the worst one. The microstructure of leaves affected particle deposition and remaining on the leaves, and PV_RSS selectively intercepted particulate matter mainly related to certain elements. 相似文献
14.
Introduction Titanium dioxide (TiO 2) nanoparticle powders have been extensively studied to quickly photodegrade some organic pollutants; however, the effect of the particle size of TiO 2 nanoparticle aggregates on degradation remains unclear because microscale aggregates form once the nanoparticle powders enter into water. Methods The degradation of azo dye by different particle sizes of TiO 2 nanoparticle aggregates controlled by NaCl concentrations was investigated to evaluate the particle size effect. Removal reactions of reactive black 5 (RB5) with TiO 2 nanoparticles followed pseudo-first-order kinetics. Results The increase of TiO 2 dosage from 40 to 70?mg/L enhanced the degradation. At doses around 100?mg/L TiO 2, degradation rates decreased which could be the result of poor UV light transmittance at high-particle concentrations. At average particle sizes of TiO 2 nanopowders less than around 500?nm, the degradation rates increased with decreasing particle size. As the average particle size exceeded 500?nm, the degradation rates were not significantly changed. Conclusions For the complete degradation experiments, the mineralization rates of total organic carbon disappearance are generally following the RB5 decolorization kinetic trend. These findings can facilitate the application of TiO 2 nanoparticles to the design of photodegradation treatments for wastewater. 相似文献
16.
Abstract Geographic and temporal variations in the concentration and composition of particulate matter (PM) provide important insights into particle sources, atmospheric processes that influence particle formation, and PM management strategies. In the nonurban areas of California, annual-average PM 2.5 and PM 10 concentrations range from 3 to 10 [H9262]g/m 3 and from 5 to 18 µg/m 3, respectively. In the urban areas of California, annual-averages for PM 2.5 range from 7 to 30 [H9262]g/m 3, with observed 24-hr peaks reaching levels as high as 160 [H9262]g/m 3. Within each air basin, exceedances are a mixture of isolated events as well as periods of elevated PM 2.5 concentrations that are more prolonged and regional in nature. PM 2.5 concentrations are generally highest during the winter months. The exception is the South Coast Air Basin, where fairly high values occur throughout the year. Annual-average PM 2.5 mass, as well as the concentrations of major components, declined from 1988 to 2000. The declines are especially pronounced for the sulfate (SO 4 2?) and nitrate (NO 3 ?) components of PM 2.5 and PM 10 and correlate with reductions in ambient levels of oxides of sulfur (SO x) and oxides of nitrogen (NO x). Annual averages for PM 10–2.5 and PM 10 exhibited similar downwind trends from 1994 to 1999, with a slightly less pronounced decrease in the coarse fraction. 相似文献
17.
This study provides the first comprehensive analysis of the seasonal variations and weekday/weekend differences in fine (aerodynamic diameter <2.5 μm; PM 2.5) and coarse (aerodynamic diameter 2.5–10 μm; PM 2.5–10) particulate matter mass concentrations, elemental constituents, and potential source origins in Jeddah, Saudi Arabia. Air quality samples were collected over 1 yr, from June 2011 to May 2012 at a frequency of three times per week, and analyzed. The average mass concentrations of PM 2.5 (21.9 μg/m 3) and PM 10 (107.8 μg/m 3) during the sampling period exceeded the recommended annual average levels by the World Health Organization (WHO) for PM 2.5 (10 μg/m 3) and PM 10 (20 μg/m 3), respectively. Similar to other Middle Eastern locales, PM 2.5–10 is the prevailing mass component of atmospheric particulate matter at Jeddah, accounting for approximately 80% of the PM 10 mass. Considerations of enrichment factors, absolute principal component analysis (APCA), concentration roses, and backward trajectories identified the following source categories for both PM 2.5 and PM 2.5–10: (1) soil/road dust, (2) incineration, and (3) traffic; and for PM 2.5 only, (4) residual oil burning. Soil/road dust accounted for a major portion of both the PM 2.5 (27%) and PM 2.5–10 (77%) mass, and the largest source contributor for PM 2.5 was from residual oil burning (63%). Temporal variations of PM 2.5–10 and PM 2.5 were observed, with the elevated concentration levels observed for mass during the spring (due to increased dust storm frequency) and on weekdays (due to increased traffic). The predominant role of windblown soil and road dust in both the PM 2.5 and PM 2.5–10 masses in this city may have implications regarding the toxicity of these particles versus those in the Western world where most PM health assessments have been made in the past. These results support the need for region-specific epidemiological investigations to be conducted and considered in future PM standard setting. Implications: Temporal variations of fine and coarse PM mass, elemental constituents, and sources were examined in Jeddah, Saudi Arabia, for the first time. The main source of PM2.5–10 is natural windblown soil and road dust, whereas the predominant source of PM2.5 is residual oil burning, generated from the port and oil refinery located west of the air sampler, suggesting that targeted emission controls could significantly improve the air quality in the city. The compositional differences point to a need for health effect studies to be conducted in this region, so as to directly assess the applicability of the existing guidelines to the Middle East air pollution. 相似文献
18.
The Imperial County Community Air Monitoring Network was developed as part of a community-engaged research study to provide real-time particulate matter (PM) air quality information at a high spatial resolution in Imperial County, California. The network augmented the few existing regulatory monitors and increased monitoring near susceptible populations. Monitors were both calibrated and field validated, a key component of evaluating the quality of the data produced by the community monitoring network. This paper examines the performance of a customized version of the low-cost Dylos optical particle counter used in the community air monitors compared with both PM 2.5 and PM 10 (particulate matter with aerodynamic diameters <2.5 and <10 μm, respectively) federal equivalent method (FEM) beta-attenuation monitors (BAMs) and federal reference method (FRM) gravimetric filters at a collocation site in the study area. A conversion equation was developed that estimates particle mass concentrations from the native Dylos particle counts, taking into account relative humidity. The R2 for converted hourly averaged Dylos mass measurements versus a PM 2.5 BAM was 0.79 and that versus a PM 10 BAM was 0.78. The performance of the conversion equation was evaluated at six other sites with collocated PM 2.5 environmental beta-attenuation monitors (EBAMs) located throughout Imperial County. The agreement of the Dylos with the EBAMs was moderate to high ( R2 = 0.35–0.81). Implications: The performance of low-cost air quality sensors in community networks is currently not well documented. This paper provides a methodology for quantifying the performance of a next-generation Dylos PM sensor used in the Imperial County Community Air Monitoring Network. This air quality network provides data at a much finer spatial and temporal resolution than has previously been possible with government monitoring efforts. Once calibrated and validated, these high-resolution data may provide more information on susceptible populations, assist in the identification of air pollution hotspots, and increase community awareness of air pollution. 相似文献
19.
Taking advantage of the continuous spatial coverage, satellite-derived aerosol optical depth (AOD) products have been widely used to assess the spatial and temporal characteristics of fine particulate matter (PM2.5) on the ground and their effects on human health. However, the national-scale ground-level PM2.5 estimation is still very limited because the lack of ground PM2.5 measurements to calibrate the model in China. In this study, a national-scale geographically weighted regression (GWR) model was developed to estimate ground-level PM2.5 concentration based on satellite AODs, newly released national-wide hourly PM2.5 concentrations, and meteorological parameters. The results showed good agreements between satellite-retrieved and ground-observed PM2.5 concentration at 943 stations in China. The overall cross-validation (CV) R 2 is 0.76 and root mean squared prediction error (RMSE) is 22.26 μg/m 3 for MODIS-derived AOD. The MISR-derived AOD also exhibits comparable performance with a CV R 2 and RMSE are 0.81 and 27.46 μg/m 3, respectively. Annual PM2.5 concentrations retrieved either by MODIS or MISR AOD indicated that most of the residential community areas exceeded the new annual Chinese PM2.5 National Standard level 2. These results suggest that this approach is useful for estimating large-scale ground-level PM2.5 distributions especially for the regions without PMs monitoring sites. 相似文献
20.
Abstract Data characterizing daily integrated particulate matter (PM) samples collected at the Jefferson Street monitoring site in Atlanta, GA, were analyzed through the application of a bilinear positive matrix factorization (PMF) model. A total of 662 samples and 26 variables were used for fine particle (particles ≤2.5 µm in aerodynamic diameter) samples (PM 2.5 ), and 685 samples and 15 variables were used for coarse particle (particles between 2.5 and 10 µm in aerodynamic diameter) samples (PM 10–2.5 ). Measured PM mass concentrations and compositional data were used as independent variables. To obtain the quantitative contributions for each source, the factors were normalized using PMF-apportioned mass concentrations. For fine particle data, eight sources were identified: SO 4 2?-rich secondary aerosol (56%), motor vehicle (22%), wood smoke (11%), NO 3 ?-rich secondary aerosol (7%), mixed source of cement kiln and organic carbon (OC) (2%), airborne soil (1%), metal recycling facility (0.5%), and mixed source of bus station and metal processing (0.3%). The SO 4 2?-rich and NO 3 ?-rich secondary aerosols were associated with NH 4 +. The SO 4 2?-rich secondary aerosols also included OC. For the coarse particle data, five sources contributed to the observed mass: airborne soil (60%), NO 3 ?-rich secondary aerosol (16%), SO 4 2?-rich secondary aerosol (12%), cement kiln (11%), and metal recycling facility (1%). Conditional probability functions were computed using surface wind data and identified mass contributions from each source. The results of this analysis agreed well with the locations of known local point sources. 相似文献
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