Fine aerosol particles (PM1): natural and anthropogenic contributions and health risk assessment

A 1-year-long sampling campaign of sub-micrometric aerosol particles (i.e. PM1, aerosol particles with an aerodynamic diameter less than 1.0 mu m) was performed in southern Italy. PM1 samples were daily collected and their content in Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Ti and Zn was determined. The trace elements measured accounted on average for about 23.3 % of the total PM1 mass. Ca, Fe, Na and Al were the most abundant ones representing on average about 86.5 % of the determined PM1 mass while the relative percentage contributions of the remaining elements were lower than 5.0 % each. Then, by applying a methodological approach based on the combined use of the enrichment factor and the chemical mass closure techniques, the natural and anthropogenic daily contributions to the PM1 mass were assessed. Results show that natural and anthropogenic sources contributed on average for about 25.6 and 74.4 %, respectively to the PM1 mass. Finally, a risk analysis was performed in order to evaluate the possible occurrence of adverse human health effects posed by the inhalation of PM1-bound trace elements measured in the area under study. Results show that the non-carcinogenic effects due to the exposure to Al, Cd, Cr, Mn and Ni in PM1 were not significant when these elements were considered both individually and simultaneously. Switching to the carcinogenic effects, it was found that the cancer risk associated to Cd, Cr, Ni and Pb in PM1 was acceptable. Also when the cumulative effect was evaluated, the excess lifetime cancer risk values found were lower than the acceptable limit indicating that 9 children in one million inhabitants and 37 adults in one million inhabitants might get cancer by the inhalation of PM1-bound Cd, Cr, Ni and Pb over lifetime.