One year intensive PM2.5 bound polycyclic aromatic hydrocarbons monitoring in the area of Tuscany, Italy. Concentrations, source understanding and implications

Polycyclic aromatic hydrocarbons (PAHs) associated to PM2.5 particles were monitored at three sites in the region of Tuscany, Italy, during the period March 2009–March 2010. PAH concentrations ranged between 0.92 ng m−3 and 13 ng m−3. The spatial and seasonal differences observed at the three sites are discussed and attributed to specific PAH sources. Benzo[a]Pyrene average annual values were below the EU limit value of 1.0 ng m−3. The results of this study suggest that emissions from commuting and work related traffic play an important role for the city of Florence, whereas for the city of Livorno, the harbor activities seem to impact the PAH burden substantially, as well. The PAH cancer risk (expressed as the "BaPE index") has shown a 6-fold decline compared to early 1990's concentrations and 2- to 3-fold decline compared to the late 1990's. - Highlights: ► Decline in the PAH levels in Tuscany as a result of strict environmental measures. ► Vehicle traffic emissions affect Florence PAH levels. ► Livorno is affected from traffic and harbor/tourism activities. ► BaPE cancer risk indices are 6-fold lower compared to 20 years ago. - Six-fold decline of the PAH cancer risk index in Tuscany during the last two decades.