Source Contribution Analysis of Polycyclic Aromatic Hydrocarbons in PM2.5 at Three Japanese Cities Using Positive Matrix Factorization with Organic Tracers

To estimate the sources of polycyclic aromatic hydrocarbons (PAHs) and their contributions to the total PAH emissions, more than 40 PAHs and organic tracers in PM2.5 collected in 3 cities of Japan were measured and a positive matrix factorization (PMF) model analysis was performed. During the warm season, high PAH concentrations were detected in Nagoya, which is located in the port area. Total PAHs were classified into five sources: biomass combustion, semivolatile PAHs, and ship and industrial emissions, which were major, and road traffic and plastic combustion, which were minor. Analysis of the ship and industrial emissions revealed that the concentrations of these sources in the severe PAH pollution event in Nagoya exceeded 15 ng/m3 and the significant contribution exceeded 80%. In addition, PAHs indicating a risk of carcinogenicity, such as 1 to 2B by IARC and 1 to B2 by U.S. EPA, had the highest contribution to this factor among the five factors such as biomass burning and ship and industrial emissions. Our results suggest that sources of high PAH emissions exist in the port areas of Nagoya. The PMF analysis performed in this study, using combustion organics as indicators, is expected to aid other countries and regions in identifying the sources of PAHs for their effective control.