Risk estimation from urban air pollution based on Diesel Exhaust Partide (DEP) measurement

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Air pollution problems by suspended particulate matter (SPM) are still serious in metropolitan areas in Japan. Especially, health (carcinogenesis) risk from diesel exhaust particles (DEP) is considered to be significant. The purpose of this research is to (1)conduct long-term black carbon (major component of DEP) field measurements using a small absorption photometer developed by our group, (2)evaluate risks and source contributions using the measurement results, and (3)show how the introduction of the low-emission vehicle can reduce urban air pollution.In 2003, after examining various measurement methods, we started measurements at ten air monitoring stations in Sapporo. The measured components are black carbon, volatile organic compounds, polynuclear aromatic hydrocarbons, heavy metals. In 2004, the measurements were continued, and an method of estimating DEP concentrations from the variations of various pollutants was examined.The main findings are as follows.(1)By using tape type absorption photometer, the high temporal variations of the black carbon were obtained.(2)Black carbon showed a seasonal variation with a maximum in autumn, and a minimum in spring.(3)From a statistical analysis and a diffusion calculation, the DEP contribution to SPM and black carbon content in DEP were estimated.(4)Assuming the DEP unit risk (3.4x10^<-5>, WHO), the estimated carcinogenesis risk level in Sapporo ranged from 1.7x10^<-4> to 3.7x10^<-4>.