Delhi Air Quality Plummets to Very Poor Category Following Diwali Celebrations

NEW DELHI — Delhi woke up to a heavy smog blanket on Monday following Diwali celebrations, registering an average Air Quality Index (AQI) of 370, which falls under the ‘very poor’ category.

Residents across the national capital faced reduced visibility on roads alongside eye and throat irritation. While the morning haze was attributed in part to an hour of firecracker bursting on Diwali night despite restrictions, Central Pollution Control Board (CPCB) data indicates that post-Diwali air quality was the worst recorded in the past five years for the day after the festival.

The broader institutional and environmental significance centres on the compounding pressures of seasonal meteorological stagnation, vehicular emissions, industrial pollutants and localized firecracker use, which routinely push Delhi’s winter air into hazardous territory despite periodic regulatory interventions and Supreme Court-mandated limits on green crackers.

Open-source air quality monitoring platforms presented starker figures, with AQI.in reporting a spike up to 2,283 overnight, while morning readings stood at 637, categorized as hazardous. On Diwali day itself, the city’s average AQI was 376, with 20 out of 59 monitoring stations recording ‘severe’ air quality during the night. Areas including Bawana, Burari, Punjabi Bagh, and Okhla persistently remained in the severe bracket.

Switzerland-based air quality monitoring platform IQAir reported fine particulate matter (PM2.5) concentrations at 170 micrograms per cubic meter, roughly 34 times higher than the World Health Organization’s annual guidelines. PM2.5 remains a primary health concern due to its capacity to penetrate deep into the lungs and enter the bloodstream. Additional pollutants detected in significant quantities included PM10, carbon monoxide, nitrogen dioxide from vehicular exhaust, and sulfur dioxide from industrial and cracker emissions.

Although Monday’s average AQI of 376 remained below the historical post-Diwali peaks seen in 2021 (462), 2016 (445), 2020 (435), and 2017 (403), several individual monitoring stations such as Sonia Vihar (449–463) and Burari (437–445) crossed into severe levels. Historical analyses show that post-Diwali AQI typically surges; for instance, the index jumped 64% from 218 to 358 between Diwali day and the following morning in 2023. Over an 11-year analysis period post-2015, average air quality deteriorates by about 16% in the four days following Diwali compared to the four days preceding it, tripling the number of severe air quality days.

Meteorological factors continue to compound the crisis. Falling temperatures, low wind speeds dropping below 10 km/h, and atmospheric stagnation trap pollutants near the surface. According to the Air Quality Early Warning System (EWS), pollution levels are projected to remain in the severe to very poor categories, with ventilation indices staying below 6,000 square meters per second.

Experts from the Centre for Research on Energy and Clean Air (CREA) warn that the convergence of festival emissions, vehicular traffic and stubble burning could push current hotspots past the 450 mark into severe conditions. Skymet weather experts noted that while brief eastern winds on the night of November 8 offered slight dispersion, subsequent weakening wind speeds would cause pollutants to re-accumulate. While the Supreme Court permitted certified green crackers for specific windows on November 7 and 8, a total ban on crackers came back into effect on November 9, with experts anticipating little natural relief in air quality through the remainder of the week.