Temporal Variations Of PM2 Research Articles

Airborne fine particulate pollution in Jinan, China: Concentrations, chemical compositions and influence on visibility impairment

Daily PM2.5 samples were collected simultaneously at an urban site (SD) and a rural site (MP) in Jinan, China from March 2006 to February 2007. The samples were analyzed for major inorganic and organic water-soluble ions, 24 elements and carbonaceous species to determine the spatial and temporal variations of PM2.5 mass concentrations and chemical compositions and evaluate their contributions to visibility impairment. The annual average concentrations of PM2.5 were 148.71μgm−3 and 97.59μgm−3 at SD and MP, respectively. The predominant component of PM2.5 was (NH4)2SO4 at SD and organic mass at MP, which accounted for 28.71% and 37.25% of the total mass, respectively. The higher SOR (sulfur oxidation ratio) and ratios of OC/EC at SD indicated that the formation of secondary inorganic ions and secondary organic aerosols (SOA) could be accelerated in the urban area. Large size (NH4)2SO4 and large size organic mass were the most important contributors to visibility impairment at SD and MP, accounting for 43.80% and 41.02% of the light extinction coefficient, respectively.

Association Between Short Term Variations in Atmospheric Pollutants’ Levels and the Couples’ Fecundability

ISEE-0822 Background and Objectives: Associations between air pollution levels and semen characteristics have been reported. However, very few studies directly documented the possible effects of atmospheric pollutants on the couples’ fecundity. Our aim was to characterize the short term effects of atmospheric pollutants on fecundability, the month-specific probability of pregnancy among non-contracepting couples. Methods: Within a cohort of births that occurred between 01/1994 and 03/1999 in the Teplice area (Czech Republic), we focused on couples who had planned their pregnancy. We restricted the study period to pregnancy attempts started from August 1993 to August 1996 to limit bias due to truncation effects. PM2.5 levels were estimated from a central measurement site and averaged over 1-month and 3-month periods before the start of the pregnancy attempt. The occurrence of a pregnancy during the first month of the pregnancy attempt was analyzed by logistic regression, which allowed estimating fecundability odds-ratio (FOR). Results: Among the 2267 recruited couples, 567 (25%) conceived during the first month of the pregnancy attempt. Compared to pregnancy attempts started after a month with a PM2.5 level below 25 μg/m3, a PM2.5 level above 45 μg/m3 during the month before the start of the pregnancy attempt was associated with an adjusted FOR of 0.69 (95% confidence interval, 0.51–0.94). When PM2.5 levels were averaged over a 3-month period, levels above 45 μg/m3 were associated with an FOR of 0.74 (95% confidence interval, 0.53–1.04). Point estimates changed little after further adjustment for season and year of the pregnancy attempt, although confidence intervals widened. Conclusion: In this polluted area, short term temporal variations in PM2.5 levels tended to be associated with a decreased fecundability. Since important economic and social changes occurred in the area during the study period, simulations are necessary to determine if these changes could explain the observed associations.

Spatial and temporal differences of Particulate Matter in Berlin

Particulate Matter (PM) is still a problem in urban areas. The concentration of PM in Berlin and its variability is the subject of this study based on data of six official PM10 monitoring stations and a measuring program carried out by the Institute of Geography covering PM2.5 and coarse PM measurements at 19 sites, distinguished between traffic related and urban background sites. The impact of weather conditions on PM levels was analysed using weather types after the Heb and Brezowsky classification. Highest PM levels were observed at traffic-related sites. However, the temporal variability of PM2.5 was more pronounced than the spatial variability, while the coarse PM (2.5-10 μm) was more influenced by the spatial conditions. The temporal variability of PM10 where more pronounced than the spatial variability.

Spatial and Temporal Variation in PM2.5 Chemical Composition in the United States

Spatial and Temporal Variation in PM2.5 Chemical Composition in the United States

Spatial and temporal variations of PM2.5 concentration and composition throughout an urban area with high freeway density—the Greater Cincinnati study

Abstract The PM 2.5 concentration and its elemental composition were measured in the Cincinnati metropolitan area, which is characterized by intense highway traffic. The spatial and temporal variations were investigated for various chemical elements that contributed to the PM 2.5 fraction during a 1-year-long measurement campaign (December 2001–November 2002). The ambient aerosol monitoring was performed in 11 locations around the city during nine measurement cycles. During each cycle, four Harvard-type impactors were operating in parallel in specific locations to explore various factors affecting the PM 2.5 elemental concentrations. The sampling was performed during business days, thus assuring traffic uniformity. The 24-h PM 2.5 samples were collected on Teflon and quartz filters. Teflon filters were analyzed by X-ray fluorescence (XRF) analysis while quartz filters were analyzed by thermal-optical transmittance (TOT) analysis. In addition to PM 2.5 measurements, particle size-selective sampling was performed in two cycles using micro-orifice uniform deposit impactor; the collected fractionated deposits were analyzed by XRF. It was found that PM 2.5 concentration ranged from 6.70 to 48.3 μg m −3 and had low spatial variation (median coefficient of variation, CV=11.3%). The elemental concentrations demonstrated high spatial variation, with the median CV ranged from 38.2% for Fe to 68.7% for Ni. For traffic-related trace metals, the highest concentration was detected in the city center site, which was close to a major highway. The particle size selective measurement revealed that mass concentration of the trace metals, such as Zn, Pb, Ni, as well as that of sulfur reach their peak values in the particle size range of 0.32–1.0 μm. Meteorological parameters and traffic intensity were not found to have a significant influence on the PM 2.5 elemental concentrations.

Short-Term Temporal Variation in PM2.5 Mass and Chemical Composition during the Atlanta Supersite Experiment, 1999

Measurements in urban Atlanta of transient aerosol events in which PM2.5 mass concentrations rapidly rise and fall over a period of 3–6 hr are reported. The data are based on new measurement techniques demonstrated at the U.S. Environmental Protection Agency (EPA) Atlanta Supersite Experiment in August 1999. These independent instruments for aerosol chemical speciation of NO3 −, SO4 2−, NH4 +, and organic and elemental carbon (OC and EC), reconstructed the observed hourly dry PM2.5 mass to within 20% or better. Data from the experiment indicated that transient PM2.5 events were ubiquitous in Atlanta and were typically characterized by a sudden increase of EC (soot) and OC in the early morning or SO4 2− in the late afternoon. The frequent temporal decoupling of these events provides insights into their origins, suggesting mobile sources in metro Atlanta as the main contributor to early morning PM2.5 and more regionally located point SO2 sources for afternoon PM2.5 events. The transient events may also have health implications. New data suggest that short-term PM2.5 exposures may lead to adverse health effects.1 Standard integrated filter-based techniques used in PM2.5 compliance monitoring networks and in most past PM2.5 epidemiologic studies collect samples over 24-hr periods and thus are unable to capture these transient events. Moreover, health-effects studies that focus on daily PM2.5 mass alone cannot evaluate the health implications of the unique and variable chemical properties of these episodes.

Temporal Variations of PM2.5, PM10, and Gaseous Precursors during the 1995 Integrated Monitoring Study in Central California

ABSTRACT The spatial and temporal distributions of particle mass and its chemical constituents are essential for understanding the source-receptor relationships as well as the chemical, physical, and meteorological processes that result in elevated particulate concentrations in California’s San Joaquin Valley (SJV). Fine particulate matter (PM2.5), coarse particulate matter (PM10), and aerosol precursor gases were sampled on a 3-hr time base at two urban (Bakersfield and Fresno) and two non-urban (Kern Wildlife Refuge and Chowchilla) core sites in the SJV during the winter of 1995–1996. Day-to-day variations of PM2.5 and PM10 and their chemical constituents were influenced by the synoptic-scale meteorology and were coherent among the four core sites. Under non-rainy conditions, similar diurnal variations of PM2.5 and coarse aerosol were found at the two urban sites, with concentrations peaking during the nighttime hours. Conversely, PM2.5 and coarse aerosol peaked during the morning and afternoon hours at the two non-urban sites. Under rainy and foggy conditions, these diurnal patterns were absent or greatly suppressed. In the urban areas, elevated concentrations of primary pollutants (e.g., organic and elemental carbons) during the late afternoon and nighttime hours reflected the impact from residential wood combustion and motor vehicle exhaust. During the daytime, these concentrations decreased as the mixed layer deepened. Increases of secondary nitrate and sulfate concentrations were found during the daylight hours as a result of photochemical reactions. At the non-urban sites, the same increases in secondary aerosol concentrations occurred during the daylight hours but with a discernable lag time. Concentrations of the primary pollutants also increased at the non-urban sites during the daytime. These observations are attributed to mixing aloft of primary aerosols and secondary precursor gases in urban areas followed by rapid transport aloft to non-urban areas coupled with photochemical conversion.