The Main Composition of PM2.5 in Three Middle American Cities

To better understand the characteristic and speciation of PM2.5 pollution in US, three American cities (including Taft; St. Bernard; Chase) were selected for monitoring in Cincinnati, Southwest Ohio from 2003 to 2013. Chase has similar levels of PM2.5 and speciation as Taft. St. Bernard both had higher levels of PM2.5, OM and EC. Taft site, which has most detailed data showed that PM2.5 mass concentrations are lower in spring and fall than in winter and summer. Reductions about 21 percent in PM2.5 mass were also be observed from 2003 (13.41 mu g/m(3)) to 2013 (10.55 mu g/m(3)). In Strong seasonal trends are also observed in sulfate and nitrate. Nitrate levels are higher in winter and sulfate is higher in summer. Sulfate was the most abundant material (33.43%) in Taft (2009 to 2013), followed by OM and nitrate (2nd and 3rd; 31.71% and 17.71%). Elemental carbon (2.84%) and crustal (3.61%), on the other hand, took much smaller portions.