Ozone pollution higher in Delhi due to heat wave; poses serious health risk: Study

Ozone level has increased manifold in the national capital due to severe heat wave this season posing a serious health risk, a recent study has revealed and suggested aggressive control of industrial and vehicular emissions.

According to the air quality index (AQI), released everyday by Central Pollution Control Board (CPCB), ozone is emerging as a dominant pollutant along with particulate matter (PM), especially in Delhi and NCR areas, said environment think tank CSE.

"It is shocking to note that according to the AQI which the CPCB releases every day, ozone, along with particulate matter, has been the dominant pollutant of the day on 28 days between April 1 and June 5, 2019.

"During the same period in 2018, ozone was the dominant pollutant along with particulate matter on only 17 days," the study by Centre for Science and Environment (CSE) said.

After tracking the daily ozone data, the CSE has found that this summer, when the capital witnessed searing heat wave, average ozone levels exceeded the prescribed standard on 16 per cent of the days overall, compared to 5 per cent of the days during the same period in 2018.

The eight-hour average standard for ozone exposure is 100 microgram per cubic metre (cu m).

The study said the highest concentration in 2019 went up to 122 microgram per cu m, which is 1.22 times higher than the eight-hour average standard. During 2018, it had gone up to 106 microgram per cu m which is 1.1 times higher than the standard.

Environment expert and CSE Executive Director Anumita Roychowdhury said, "If this trend continues and worsens, the Graded Response Action Plan (GRAP) will also have to initiate action to address the precursor gases that form ozone -- NOx, hydrocarbons etc -- and crack down on vehicles and industry."