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Spatial and Temporal Variability of Outdoor Coarse Particulate Matter Mass Concentrations Measured with a New Coarse Particulate Sampler during the Detroit Exposure and Aerosol Research Study
Citation:
Thornburg, J., C. E. RODES, P. A. Lawless, AND R. W. WILLIAMS. Spatial and Temporal Variability of Outdoor Coarse Particulate Matter Mass Concentrations Measured with a New Coarse Particulate Sampler during the Detroit Exposure and Aerosol Research Study. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 43(28):4251-4258, (2009).
Impact/Purpose:
The National Exposure Research Laboratory′s (NERL) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA′s mission to protect human health and the environment. HEASD′s research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA′s strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.
Description:
The Detroit Exposure and Aerosol Research Study (DEARS) provided data to compare outdoor residential coarse particulate matter (PM10-2.5) concentrations in six different areas of Detroit with data from a central monitoring site. Daily and seasonal influences on the spatial distribution of PM10-2.5 concentrations during Summer 2006 and Winter 2007 were investigated using data collected with the newly developed coarse particle exposure monitor (CPEM). These data allowed the representativeness of the community monitoring site to be assessed for the greater Detroit metro area. Multiple CPEMs collocated with a dichotomous sampler determined the precision and accuracy of the CPEM PM10-2.5 and PM2.5 data. CPEM PM2.5 concentrations agreed with the dichotomous sampler data. The slope was 0.97 and the correlation coefficient was 0.91. CPEM PM10-2.5 concentrations had an average 23% negative bias and correlation coefficient of 0.81. The directional nature of the CPEM sampling efficiency probably caused the negative CPEM concentration bias. Coarse particle concentrations were observed to vary spatially and temporally across Detroit, reflecting the seasonal impact of local sources. Summer PM10-2.5 concentrations were 5 μg/m3 higher in the two industrial areas near downtown than the average concentrations in other areas of Detroit. An area impacted by vehicular traffic had concentrations 8 μg/m3 higher than the average concentrations in other parts of Detroit in the winter due to the suspected suspension of road salt. Pearson correlations for PM10-2.5 concentrations between monitoring locations varied from 0.03 to 0.76. All summer PM10-2.5 concentration correlations were greater than 0.28 and statistically significant (p-value < 0.05). Winter PM10-2.5 concentration correlations greater than 0.33 were statistically significant (p-value < 0.05). The PM10-2.5 correlations found to be insignificant were associated with the area impacted by mobile sources during the winter. The suspected suspension of road salt from the Southfield Freeway, combined with a very stable atmosphere, caused PM10-2.5 concentrations to be greater in this area compared to other areas of Detroit. These findings indicated that PM10-2.5 concentrations, although correlated in some instances, vary in magnitude sufficiently that a central monitoring site may not adequately represent the population exposure in a complex urban airshed.
URLs/Downloads:
Atmospheric Environment
Spatial and Temporal Variability of Outdoor Coarse Particulate Matter Mass Concentrations Measured with a New Coarse Particulate Sampler during the Detroit Exposure and Aerosol Research Study (PDF, NA pp, 834 KB, about PDF)