Transects Modeling from Bisecting Roadways for Particulate Matter 2.5 (PM_(2.5)), Elemental Carbon (EC), and Nitrogen Dioxide (NO2) in Homewood, PA

摘要

While large scale monitoring can quantify exposure to pollutants for cities or regions, more specific variations in pollutant levels at a community level require more saturated sampling or sampling on a smaller scale. Monitoring directly at points of interest may not fully capture the spatial variability of pollutants, therefore a spatial saturation model using transects may provide a more reliable estimate of for the entire sampling domain. We partnered with the Homewood Children's Village, a community organization concerned with their neighborhood air quality in areas where children spend a significant amount of time outdoors. Using transect modeling across the entire community, we aimed to establish a gradient or exposure map for PM_(2.5), NO2 and EC. Two main roads identified by the heaviest traffic patterns bisect the community lengthwise. Considering only roads within the community, a transect model was developed with 22 sites sampled at varying distances, relative to the main roads. A reference site from within the community was used to adjust for temporal variation. PM_(2.5) was collected via active filters and NO2 via passive badges on stationary monitors for 4, 7-day periods in Oct.-Nov. 2013. PM_(2.5) ranged from 3.1-9.8 μg/m3 (mean = 7.1) and NO2 ranged from 11.9-16.7 ppb (mean = 13.7) once temporally adjusted to the reference site. Elemental carbon (EC) was also measured from the filters and ranged from 1.7-6.5 absorbance units (mean = 4.0). Considering the main bisecting roads as the source of pollutants for the transect sampling pattern, NO2 showed a significant (a = 0.05) trend and no pattern was observed in PM_(2.5) or EC. While transects from the main roads showed no trends for PM_(2.5) and EC, NO2 demonstrates a trend of decreasing concentration with increasing distance. External bordering roads with higher traffic density did show a pattern of decreasing all measured pollutants concentrations with increased distance.