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 μm) 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.