A set of 8 polycyclic aromatic hydrocarbons (PAHs) has been analysed in a traffic-limited area in Bologna downtown, both in the gas-phase and in the particulate phase (PM 10), and gas-to-particle partitioning has been investigated. From Sep 2002 to May 2003, 28 high volume PM 10 samplings were carried out, and in 50% of the samplings, PM 10 concentrations exceeded the limit of 50 μg/m 3 established by a 1999 EU directive. A precisely defined sampling strategy was adopted to limit artifacts (8 h sampling in the same time interval) in the 28 samplings carried out in different meteorological conditions. A linear log-log correlation was found between gas-particle partitioning coefficients KB P and the subcooled liquid vapour pressures pB 0 L B, with rP 2P = 0.82 and slope = -0.59. This empirical correlation may be used to anticipate the total (gas + particle-bound) concentration of each PAHs in this urban site, once PM 10 and the particle-bound concentration is measured. Parallel samplings of PM 10 and of PM 2.5 allowed us to ascertain that PM 2.5 represents the gross contribution to PM 10 and that most of the particle-bound PAHs reside on the finest fraction of particulate matter.

cited By 5