Spatial and seasonal distribution of aerosol chemical components in New York City: (2) Road dust and other tracers of traffic-generated air pollution

We describe spatial and temporal patterns of seven chemical elements commonly observed in fine particulate matter (PM) and thought to be linked to roadway emissions that were measured at residential locations in New York City (NYC). These elements, that is, Si, Al, Ti, Fe, Ba, Br, and black carbon (BC), were found to have significant spatial and temporal variability at our 10 residential PM2.5 sampling locations. We also describe pilot study data of near-roadway samples of both PM10-2.5 and PM2.5 chemical elements of roadway emissions. PM2.5 element concentrations collected on the George Washington Bridge (GWB) connecting NYC and New Jersey were higher that similar elemental concentration measured at residential locations. Coarse-particle elements (within PM10-2.5) on the GWB were 10-100 times higher in concentration than their PM2.5 counterparts. Roadway elements were well correlated with one another in both the PM2.5 and PM10-2.5 fractions, suggesting common sources. The same elements in the PM2.5 collected at residential locations were less correlated, suggesting either different sources or different processing mechanisms for each element. Despite the fact that these elements are only a fraction of total PM2.5 or PM10-2.5 mass, the results have important implications for near-roadway exposures where elements with known causal links to health effects are shown to be at elevated concentrations in both the PM2.5 and PM10-2.5 size ranges. Journal of Exposure Science and Environmental Epidemiology (2011) 21, 484-494; doi: 10.1038/jes.2011.15; published online 27 April 2011