Delhi air quality remains ‘very poor’ post Diwali; farm fire fuels rising pollution: CSE report

Delhi's PM2.5 levels peaked on Diwali night, 13% higher than last year, due to traffic congestion and farm fires.

Delhi's PM2.5 levels hit a peak by midnight on Diwali this year, which was 13% higher than the peaks observed last year and in 2022, a recent analysis by the Centre for Science and Environment (CSE) showed.

“The Diwali night this year had higher nitrogen dioxide (NO2) levels that indicate high traffic congestion,” the CSE report said.

The research organisation's report also said, unlike previous years, on Diwali night in Delhi, there was a quick buildup of PM2.5 levels and dissipation the next day.

“By midnight on October 31, PM2.5 hit a peak of 603 µg/m³, 13% higher than Diwali peaks observed in 2022 and 2023,” the report stated.

Meanwhile, according to a report by the Delhi Pollution Control Committee (DPCC), the PM2.5 levels decreased by 4% as compared to Diwali last year.

PM2.5 are fine inhalable particles with a diameter that is generally 2.5 micrometres or smaller and are hazardous for health conditions. The acceptable annual standard for PM2.5 is 40 micrograms per cubic metre.

The CSE report said PM2.5 levels were already rising steadily during the preceding five days leading up to Diwali and showed a marked increase of 46% from October 28 through October 31.