Assessment of Japanese Photochemical Ozone Pollution by 8-hour Average Concentration

Abstract

Ozone concentrations monitored at Japanese air pollution and acid deposition monitoring stations from 2005 through 2007 were assessed based on their 8-hour average, which is used in the assessment method of the United States Environmental Protection Agency (USEPA) standard and World Health Organization (WHO) guideline, in order to evaluate the Japanese photochemical ozone pollution. The assessed values at almost all the stations exceeded the WHO guideline, while 22 % of the stations met the USEPA standard. A grid average data analysis showed that about 11 % of the population lives in an area in which the ozone concentration met the USEPA standard. From a comparison with the USA and European countries based on the USEPA standard assessment, it was found that Japanese photochemical ozone pollution was more serious especially in the urban and suburban areas. To evaluate the ozone pollution in Japan, the annual maximum 8-hour average and/or annual maximum value of the daily maximum 8-hour average after removing outliers were considered to be effective as a robust representative value which reflects high concentration events.