In order to investigate the sources and carcinogenicity of polycyclic aromatic hydrocarbons (PAHs) in aerosol particles in the urban atmosphere of Kumamoto, Japan, atmospheric particles were collected by using two high volume air samplers at a roadside site and a residential site during December 2003 ∼ May 2004, and 16 major PAHs in the samples were analyzed with GC-MS. It was confirmed that the PAHs were mainly from diesel and gasoline engines as expected at both sites. At the roadside site, the total concentration of the 16 PAHs was 10.08 ∼ 99.12 ng m-3 with the average 46.60 ng m-3. At the residential site it was 11.68 ∼ 60.93 ng m-3 with the average 30.03 ng m-3, which is apparently smaller than that at the roadside site. However, the carcinogenicity of the particulate PAHs at the residential site was approximately at the same level as that at the roadside site. Benzo(b)fluoranthene (BbF) , Benzo(k)fluoranthene (BkF) and Dibenzo(a.h)anthracene (DahA) were the major contributors to the carcinogenicity. The concentration of DahA was much smaller than that of BbF and BkF at both sites, but it was considerably larger at the residential site than at the roadside site, which made the carcinogenicity at the residential site comparable to that at the roadside site.
