Abstract
In Japan, the first photochemical air pollution epispde was reported in 1970. These episodes were observed often in middle and high school students in Tokyo andOsaka who exercised in the daytime during the photochemical air pollution season. The observed symptoms were divided into three categories: irritating symptoms of eye, throat and airway; general symptoms such as headache, nausea, dizziness and lastitude, etc., and neurological symptoms such as numbness in the extremities, convulsions, and unconsciousness. The health risk assessment for evaluating the causal relationship between the observed symptoms and air pollutants was made by epidemiological and clinical human exposure studies. The result showed thatthe irritating symptoms of airway were due mainly to exposure to ozone. Althoughthe mechanisms of the general and neurological symptoms other than respiratory irritation could not be determined in these studies, a level of 0.15ppm ozone produced significant respiratory effects when the subj ct undertook light exercise.
