Delhi's air pollution reached alarming levels on Monday morning, with the city's Air Quality Index (AQI) climbing to 637 at 9 am after a night of Diwali celebrations and firecracker bursts. The AQI had peaked at 1,331 at 1.31 am, according to AQI.in data.
The morning reading was nearly 69 per cent higher than the AQI of 393 recorded by the same platform on October 21, 2025, the day after Diwali last year, indicating a sharp deterioration in post-festival air quality.
Despite restrictions on firecrackers, residents across the national capital continued to burst crackers on Sunday evening, adding smoke and fine particulate matter to an already polluted atmosphere.
Monitoring stations across Delhi recorded similarly high pollution levels, while a blanket of grey haze reduced visibility and obscured roads and high-rise buildings.
In October, the Supreme Court had imposed restrictions on conventional firecrackers and permitted the use of approved green crackers under specified conditions during three-hour windows on Saturday and Sunday. Although these crackers generate fewer emissions, they are not pollution-free and continue to release particulate matter and other pollutants.
Delhi-NCR, home to more than 30 million people, regularly experiences severe air pollution during the winter months. The annual deterioration is driven by a combination of Diwali fireworks, vehicular emissions, industrial activity, construction dust and agricultural residue burning in neighbouring states.
After harvesting paddy, farmers in Punjab and Haryana often burn leftover crop stubble to clear their fields for the next sowing cycle. Smoke from these fires travels towards the national capital, adding to pollution from local sources.
The situation typically worsens in late October and November as falling temperatures, low wind speeds and stagnant atmospheric conditions prevent pollutants from dispersing. This allows a thick layer of smog to persist over Delhi and neighbouring areas for several days.
Authorities have introduced several measures to tackle the pollution, including restrictions on construction activities and diesel generators, alongside curbs on firecrackers. However, these interventions have failed to prevent the recurrence of severe pollution during the winter.
Environmentalists have called for longer-term measures, including a transition to cleaner energy and stricter controls on vehicular emissions, to address the recurring crisis.