Despite 77.5% drop in stubble burning, Delhi’s air quality hits a five-year post-Diwali low

The data paints a grim picture, a 212 per cent spike in pollution compared to pre-Diwali readings, and a peak level of 675 micrograms per cubic metre on Diwali night.

Air quality this Diwali was the worst in three years, despite the Supreme Court’s conditional approval for “green” firecrackers within limited hours.

In reality, those limits were widely ignored, leaving Delhi blanketed in a thick, chemical haze through the night and into Tuesday morning.

This year’s Air Quality Index (AQI) easily surpassed last year’s 328, as well as 312 in 2022 and 218 in 2023, confirming that even so-called “green” firecrackers failed to curb the toxic pollution.

'Green' crackers no solution

Four years of Central Pollution Control Board (CPCB) data show that Diwali 2025 was one of the most polluting in recent memory.

The findings highlight a worrying trend: Delhi’s annual Diwali spike in pollution is increasingly local and human-made, driven by firecracker smoke that lingers for days.

“The data shows post-Diwali PM2.5 readings averaged around 488, compared to 156.6 before the festival. That’s more than a threefold increase and makes 2025 one of the most polluted Diwalis in recent years,” said Palak Balyan, lead researcher at Climate Trends, a Delhi-based environmental think tank, speaking to NDTV.

Low wind speeds, below one metre per second, prevented pollutants from dispersing, while a sharp temperature drop from 27°C to 19°C trapped smoke close to the ground through a temperature inversion, worsening conditions overnight, according to reports.

While farm fires in Punjab and Haryana have long been blamed for Delhi’s toxic air, data from this year tells a different story.

Floods in those states earlier in 2025 naturally reduced stubble burning, serving as an unintended experiment. The 77.5 per cent drop in stubble fires coincided with a 15.5 per cent decline in Delhi’s PM2.5 levels through October, confirming that while farm fires are a factor, they’re not the only culprit.

Even with fewer fires, PM2.5 levels in Delhi remained dangerously above 50 micrograms per cubic metre, pointing to persistent local sources such as traffic, industry, and dust.