Local and Regional Contributions of Fine Particulate Mass to Urban Areas in the211 Mid-Atlantic and Southwestern U.S

摘要

This work examined the seasonal local and regional contributions of PM2.5 to211u001eurban areas in the Mid-Atlantic States: Baltimore, MD, Washington, DC, and 211u001ePhiladelphia, PA and Phoenix, AZ in the Southwest. This was accomplished using 211u001etwo different methods. The first method estimated urban excesses by comparing 211u001eseasonal PM2.5 trends at the urban monitors to nearby rural monitors. The second 211u001eapproach used a simple model based on the PM2.5 dependence on wind speed and wind 211u001edirection to classify a site as being dominated by local or regional source 211u001econtributions. The method also quantifies the regional contributions during high 211u001ewind speed conditions. The wind vectors were derived from surface observations 211u001eand air mass histories. All monitoring sites in the urban centers were dominated 211u001eby local sources during the cold season.