Concentrations of particle-bound polycyclic aromatic hydrocarbons (PAHs) and chlorinated PAHs (CIPAHs) were measured in different seasons at five sampling stations in Nagoya, a Japanese megacity. The annual mean total CIPAH and total PAH concentrations were 43.3-92.6 pg/m(3) and 5200-8570 pg/m(3), respectively. The concentrations of total CIPAHs were significantly variable than those of total PAHs, and both total concentrations through the seasons did not significantly correlate at any of the stations. Principal component analysis was used to characterize the CIPAH sources, resulted that CIPAHs were found to be associated with the sources of high-molecular-weight PAHs in the warmer seasons and of low-molecular weight PAHs in the colder seasons. These findings suggest that principal sources of particle-bound CIPAHs are present in the local area, and change in the seasons. Toxic equivalent (TEQ) concentrations were estimated to assess the risks associated with exposure to CIPAHs in air. The TEQ concentrations in the samples were 0.05-0.32 pg-TEQ/m(3). The TEQ concentrations in summer were approximately half the TEQ concentrations in the other seasons at all of the stations. (C) 2016 Elsevier B.V. All rights reserved.