Delhi Air Pollution Data Goes Missing at Key Stations After Diwali Firecracker Bursting

UPDATE - follow-up to At peak of air pollution on Deepavali night, data goes missing at several govt monitoring stations in Delhi: Air pollution in Delhi rose to over 150 to 200 times WHO limits on Deepavali night as people burst firecrackers past the Supreme Court's 10 p.m. deadline. During this peak pollution window, crucial data went missing from several government-managed monitoring stations. Experts warn that missing peak values will make air quality look better than it actually was. Traditional firecrackers were sold in markets despite the court allowing only green firecrackers within fixed windows. Data from the Delhi Pollution Control Committee showed PM2.5 levels in Patparganj reached 2,597 micrograms per cubic metre at 1 a.m. on Monday, which is 173 times the WHO limit. At the NSUT West Campus, PM2.5 levels hit 3,008.4 micrograms per cubic metre by 5 a.m., marking 200.5 times the permissible limit. Fine inhalable particles of PM2.5 can enter the lungs and bloodstream and cause respiratory diseases. Gufran Beig, chair professor at the National Institute of Advanced Studies, noted that wind speed and direction helped clear the air through Monday morning. The wind shifted from north-westerly to easterly and south-easterly by Sunday afternoon, cutting out the effect of stubble burning. Meanwhile, Delhi's overall 24-hour AQI stood at 344 at 4 p.m. on Monday, improving from 376 a day earlier. Political parties clashed over the situation. The AAP and the Congress criticized the BJP government, with the AAP calling the missing data "data fraud". In response, Delhi Labour Minister Kapil Mishra claimed there was a conspiracy by AAP-governed Punjab to burn stubble on Sunday evening. Punjab recorded 1,152 stubble burning incidents on Sunday, the highest for the season, before dropping to 198 on Monday. Stubble burning contributed 5.1% to Delhi's PM2.5 levels on Sunday.

Context

Air quality in Delhi and the wider Indo-Gangetic Plains worsens every winter due to dropping temperatures, low wind speeds, vehicle emissions, dust, stubble burning, and festive firecrackers. Official monitoring networks track these pollutants using automated stations, though gaps in reporting can hinder accurate public assessments during peak pollution events.