Delhi's Diwali air was the worst in 5 years, and data went missing too

Delhi's Diwali pollution has rocketed to its worst level in five years. And just when the air was at its dirtiest, a lot of the numbers stopped showing up.

What happened?

Delhi's average AQI (air quality index) hit 376 on Diwali day, firmly in the "very poor" range. By the next morning, the city woke up to thick haze, with some areas above 400.

Then came the data problem. PM2.5 readings (the tiny, lung-clogging particles) went blank on Diwali night, just as they were nearing 1,000. According to reports, 227 PM2.5 observations were missing across 59 monitoring stations on the website of the CPCB (Central Pollution Control Board, India's pollution regulator).

Experts say those gaps understated the city's real pollution levels. Several stations simply stopped reporting for hours, while the ones still working recorded severe air.

Why is everyone talking about it?

Because the timing looks awkward. Saurabh Bharadwaj of the opposition Aam Aadmi Party (AAP) alleged "AQI data fraud" by the government and claimed Delhi's AQI crossed 3,000. That figure is his allegation, not an official reading.

The government has not accepted that charge. Mishra said the government will look into the missing data.

It's also a wider regional story. Loni, about 30 km from Delhi, ranked among the world's most polluted places in an annual list by Swiss monitoring firm IQAir. It is one of five areas in the Delhi metropolitan region on that list.

What came before?

Last year, on 15 October 2025, the Supreme Court allowed limited use of green firecrackers (lower-emission crackers) in Delhi-NCR for Diwali. This year's numbers are now being measured against that backdrop.

Environmentalist Sunita Narain has also weighed in on the post-Diwali air crisis in Delhi and North India and on possible solutions.

What's next?

The government says it will examine why the data went missing. Whether the gaps were a technical failure is not something the available information settles. For now, the official picture is of "very poor" air, and experts say the real picture may be worse.