Concentrations of nano and related ambient air pollutants at a traffic sampling site

A micro-orifice uniform deposit impactor (MOUDI) and a nano-MOUDI were used to measure the atmospheric coarse (PM2.5 (10)), fine (PM2.5), ultrafine (PM0.056 (1)) and nano (< 0.056 mu m) particle concentrations and size distributions at a traffic sampling site in winter in central Taiwan, from November 2004 to January 2005. Concentrations of metallic elements ( Fe, Mg, Cr, Zn, Pb, Cu) and major ion (SO42-, NO3-, NH4+) in particles of various sizes (nano, ultrafine, fine and coarse) were measured. Ambient air particulates generally exhibited a bimodal size distribution in the range 0.056-10 mu m. The results show that the concentrations followed the order, Fe > Mg > Cr > Zn > Pb > Cu in PM10, fine, ultrafine and nano-sized particles. Moreover, the data showed that the average metallic elements Fe and Zn have similar concentration distributions: the concentration decreased as the particle size fell in the nano size range.