Concentrations of PAHs, and nitro- and methyl- derivatives associated with a size-segregated urban aerosol

Size-segregated atmospheric particles were collected in Rome, Italy, using a low-pressure impactor. Twelve sampling campaigns were conducted under different meteorological conditions over a whole year covering 155 not consecutive days. The samples were analyzed for polycyclic aromatic hydrocarbons (PAHs) and their nitro- and methyl- derivatives known for their toxicity. An assessment of the carcinogenic potency of the particles known to penetrate into lungs, liver, heart and nervous system was performed. The distribution of the classes of compounds was unimodal and centrated at 0.4 pm size fraction for PAHs and bimodal and centrated at 0.1 and 0.4 pm for methyl- and nitro- derivatives. The 18% of toxic organic compounds we analyzed was distributed into the ultrafine fraction (PM0.1) and 76% in the fine fraction; but substituted PAH distribution in the ultrafine particles shifted toward higher values during warm periods. In July, the 50% of the total nitro-PAHs was found in PM0.1 and an average of 42% of the total methyl-PAHs was found in the same fraction in summer and intermediate seasons. An evaluation of the potential toxicity of the measured compounds was tentatively assessed based on Potency Equivalency Factors (PEF). (C) 2010 Elsevier Ltd. All rights reserved.