Ohzone! Rising levels a danger to life
NEW DELHI: The Centre for Science and Environment has cautioned against rising ozone levels in Delhi in the summer months. If allowed to go unchecked, this dangerous pollutant, which is difficult to trace, could create a serious public health crisis. CSE said the areas in the city most affected by ozone were south Delhi and New Delhi. CSE pointed out that the current policy and public attention is nearly fully focused on particulate matter pollution and has neglected the mitigation of toxic gases. Inadequate monitoring, limited data and other drawbacks have weakened the understanding of this growing public health hazard. "Learn from the advanced economies. After controlling particulate pollution, they are in a crisis over nitrogen oxides and ozone," said Anumita Roychowdhury, executive director, research and advocacy, CSE. "India should avoid this trap, but the standard practice of the Central Pollution Control Board averaging out the data of all weather stations to determine the daily AQI cannot capture the public health risk from this short-lived and hyper-localised pollutant." Based on CPCB stations, CSE determined that between 2019 and 2023, ozone standards breached safe standards in March-May in each station in the NCR. There are two sets of standards for ozone: an eight-hour norm of 100 micrograms per cubic metre and one hourly standard of 180 micrograms per cubic metre. CSE noted the ozone data of CPCB is capped at 200 microgram per cubic metre, leaving it impossible to determine the concentration beyond that. Avikal Somvanshi, senior programme manager, CSE, said, "Compliance requires that the standards are met for 98% of the time annually. It may exceed the limit on 2% of the days, which means just eight days in a year, but not on two consecutive days." Speaking of risks, CSE's analysis said that age-standardised rates of death attributable to ground-level ozone was among the highest in India and the seasonal 8-hour daily maximum concentrations have recorded one of the highest increases in the country between 2010 and 2017 - about 17%. The analysis said New Delhi and south Delhi were worst affected by ground-level ozone pollution. Nehru Nagar in south Delhi was the most chronically affected, having exceeded the standard on 75 days in March-May. It was followed by Aurobindo Marg, Karni Singh Shooting Range and Mandir Marg. Mandir Marg in New Delhi registered the highest increase, 63%, in exceedance days compared with the average of the last four summers. It was followed by Gwal Pahari in Gurgaon and Patparganj in east Delhi, both recording 51 exceedance days.
