Ground-level ozone has been the lead pollutant on 10 of the 17 days this October, according to the Central Pollution Control Board (CPCB). While October normally sees the highest ozone levels, this year’s concentration exceeded 90 micrograms per cubic metre on several days, making it the highest for October since 2020.

A significant increase in ground-level ozone pollution is raising alarms, with experts warning of severe, long-term health risks for Delhi residents.