OZONE POLLUTION IN THE URBAN ATMOSPHERE OF DELHI

Measurements of ozone in the urban environment of Delhi were carried out synoptically at four different sites during 1989-1990. The amount of ozone in the ambient air varied from 9.4 to 128.31 ppbv exhibiting wide temporal and seasonal variation. The ozone concentration invariably peaked at noontime and remained high during early summer and spring periods. On many occasions 1-h ozone concentration was more than 113 ppbv, which represents the maximum 1-h limit of ozone in ambient air as prescribed by the U.S. EPA. The results of the study show that there is a significant build up of tropospheric ozone in the urban environment of Delhi.