The concentration of ozone in 5 major cities in Korea( Seoul, Pusan, Taegu, Kwangjoo, Incheon ) has been shown increasing trend after 1984, while decreasing trend in Hsan. According to the data from 12 monitoring stations in 9 cities of metropolitan area from January 1994 to August 1994, ozone concentration exceeded short term standard 99 times and 87%(861imes) of those was occurred during July and Augusta while the maximum ozone concentration was appeared mainly between 14: 00 and 17: 00 daily. As the result of epidemiological survey, main substances which irritate eyes were identified to be PAN and formaldehyde rather than ozone while ozone was identified to be reachable to deep part of respiratory system main target organ of ozone.