Seven factors were similarly identified (Fig. 2) as vehicle exhaust, secondary nitrate, secondary sulfate, mineral, aged sea salt, fuel oil combustion and industrial processes.The eighth factor in the PMF2 solution, with high concentrations of TC, Fe, Cu and Sb, was identified as brake particles and was also resolved byME-2 but only in the base run.In the second section of ME-2 analysis, this factor was conducted toward the target emission profile of road dust resuspension by means auxiliary equation (6) for each constituent.Since the data were assembled from multiple size fractions and also because of the absence of a known emission profile for PM2.5, the same source profile was used for all size fractions.