Delhi-NCR in grip of ozone build-up, says CSE analysis

New Delhi: Delhi and its neighbouring cities such as Faridabad and Gurgaon have witnessed a “substantial ozone build-up” from February to May, according to a green body, which has cautioned that it was early signs of a “dangerous trend”.

The Centre for Science and Environment (CSE) said that it has analysed real-time air quality data available from 31 automatic monitoring stations of the Delhi Pollution Control Committee, the Central Pollution Control Board and the India Meteorological Department for the months of February and May.

“This shows progressive increase in ozone pollution with the onset of the summer months. Several densely populated areas have shown a high frequency of days violating the ozone standards. With high pollution and temperature levels, and growing heat stress, formation of ozone has accelerated and is frequently exceeding the standards,” the CSE stated.

According to the analysis, at least on 23 days, ozone has emerged as a “dominant pollutant” along with particulate matter in the daily air quality index (AQI). “These are the early signs of a dangerous trend,” the CSE added. It also claimed that green areas on the outskirts of the national capital were “most vulnerable”. Ozone is formed in polluted areas and some of that escapes with the wind to cleaner environments. It build ups there because it has no opportunity to further react with other pollutants to dissipate as it happens in polluted areas in a cyclical process, it said.

The posh Lutyens’ Delhi area and prime places in central Delhi were also affected, the analysis said.

The analysis stated that air quality monitoring in JLN Stadium, near Lodhi Road, CGO Complex, and Major Dhyan Chand National Stadium have shown that the number of days with levels exceeding the standards were “47 per cent and 22 per cent of all days” during the entire period, respectively.

The micro-mapping of ozone levels across the city to understand the vulnerable areas, showed that there were some locations where “50 per cent” of the days between February and May, ozone levels exceeded the standards.

“These areas include the residential areas of Patparganj, R.K. Puram and Nehru Nagar; and industrial areas and low-income areas of Najafgarh and Sonia Vihar.”

“While we know that ozone escalates during summer, the surprise this year is the number of days when the AQI has shown ozone as a dominant pollutant along with the PM,” executive director and head of CSE’s air pollution programme, Anumita Roychowdhury, said.

“In addition to this, the highest eight-hour ozone levels have been recorded in Najafgarh, Patparganj, Punjabi Bagh and Pusa where on certain days the levels have gone up close to two times the standard,” the CSE statement stated.

Gurgaon and Faridabad, in the NCR, have recorded “highest number” of days with levels exceeding the standards.