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 PM(2.5) sampling locations. We also describe pilot study data of near-roadway samples of both PM(10-2.5) and PM(2.5) chemical elements of roadway emissions. PM(2.5) 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 PM(10-2.5)) on the GWB were 10-100 times higher in concentration than their PM(2.5) counterparts. Roadway elements were well correlated with one another in both the PM(2.5) and PM(10-2.5) fractions, suggesting common sources. The same elements in the PM(2.5) 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 PM(2.5) or PM(10-2.5) 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 PM(2.5) and PM(10-2.5) size ranges.