Understanding intra-neighborhood patterns in PM_2.5 and PM ₁₀ using mobile monitoring in Braddock, PA

Background: Braddock, Pennsylvania is home to the Edgar Thomson Steel Works (ETSW), one of the few remaining active steel mills in the Pittsburgh region. An economically distressed area, Braddock exceeds average annual (>15 μg/m§ssup§3§esup§) and daily (>35 μg/ m§ssup§3§esup§) National Ambient Air Quality Standards (NAAQS) for particulate matter (PM_2.5). Methods. A mobile air monitoring study was designed and implemented in morning and afternoon hours in the summer and winter (2010-2011) to explore the within-neighborhood spatial and temporal (within-day and between-day) variability in PM_2.5 and PM₁₀. Results: Both pollutants displayed spatial variation between stops, and substantial temporal variation within and across study days. For summer morning sampling runs, site-specific mean PM_2.5 ranged from 30.0 (SD = 3.3) to 55.1 (SD = 13.0) μg/m§ssup§3§esup§. Mean PM₁₀ ranged from 30.4 (SD = 2.5) to 69.7 (SD = 51.2) μg/m§ssup§3§esup§, respectively. During summer months, afternoon concentrations were significantly lower than morning for both PM _2.5 and PM₁₀, potentially owing to morning subsidence inversions. Winter concentrations were lower than summer, on average, and showed lesser diurnal variation. Temperature, wind speed, and wind direction predicted significant variability in PM_2.5 and PM₁₀ in multiple linear regression models. Conclusions: Data reveals significant morning versus afternoon variability and spatial variability in both PM_2.5 and PM₁₀ concentrations within Braddock. Information obtained on peak concentration periods, and the combined effects of industry, traffic, and elevation in this region informed the design of a larger stationary monitoring network.