Long-term measurement of various volatile organic compounds and air quality assessment using OH reactivity and ozone formation potential in sub-urban area of Tokyo

Abstract

To evaluate the air quality of a suburban area of Tokyo, the long-term measurement of volatile organic compounds (VOCs, 58 species) was conducted at Hachioji, Tokyo, Japan. The measurements were carried out from May 2002 to December 2008. Canister samples were taken once a week and analyzed using a gas chromatograph equipped with a flame ionization detector. Though the benzene concentration showed a decreasing trend during the past 7 years, no defined trend was found for the other VOCs. Most of the VOCs did not show any clear seasonal variation, but some VOCs from biogenic activity and fuel evaporation showed seasonal variations with higher concentrations during the summer. The OH reactivity (k_OH) and ozone formation potential (OFP) were deduced from the observed VOC concentrations. When comparing the VOC concentrations, k_OH, the OFP for each season, the dominant VOCs were different. Also, the contribution of alkane, alkene, aromatics and biogenic VOCs are different for the VOC concentrations, k_OH, OFP. It is important to use a suitable index in order to diagnose the air quality.