Assessment of ozone phytotoxic potential of dense vegetation cover of Delhi by AOT40

Tropospheric ozone (O3) is popularly known as phytotoxic agent. Very few studies have been performed on AOT40 index which is used as the principal measure of ozone pollution for assessing effects on vegetation in a developing country, India. Our present study focus on analysis of ozone with respect to its phytotoxic potential of a dense vegetation cover of Delhi from year 2015 - 2016. The phytotoxic potential is estimated based on AOT40 exposure index for forests calculated from real-time monitoring data at 2 dense vegetation sites. Our results indicate high phytotoxic potential for most of the Delhi city with considerable spatial variability. The highest AOT40 values were found to be 40-45 ppm.h. The critical level for forest protection (5 ppm.h) was usually found in the month of May. In the months of April - July, the critical level for dense vegetation cover exceeded over 15% of the normal value. Keywords: AOT40, ozone, dense vegetation, Delhi.