Seasonal and daily source apportionment of polycyclic aromatic hydrocarbon concentrations in PM10 in a semirural European area.

Polycyclic aromatic hydrocarbons (PAH) were analyzed from ambient air particulate matter (PM10) that was collected near Lago Maggiore (Lombardy) in Northern Italy from August 2008 to January 2009. Highest individual PAH concentrations ranged from 0.05 ng/m3 during mid-days in summer to about 6 ng/m3 duringthe nights of the coldest period. A multivariate experimental regression model for the estimation of PAH concentrations was used to apportion the identified local sources of PAHs. This model included specific markers (i.e., levoglucosan for wood combustion and hopanes for traffic emission) and meteorological parameters (i.e., ambient air temperature and atmospheric mixing layer heights). In autumn and winter, wood combustion on a daily average contributed from 30 to 70% to the PAHs in ambient air PM10. In this period, the contribution of the wood combustion was less than 30% during mid-day, increasing sometimes to more than 80% during the night In the samples taken during the summer period, traffic contribution to PAH concentrations was about 30%, while wood combustion was insignificant.