Delhi Overtakes Lahore as World’s Most Polluted City: AQI Hits 334 “Hazardous”

Delhi Became the Most Polluted City on 13th November 2026

On Friday, 13 November 2026, Delhi moved to the top of the world’s most polluted cities list, ahead of Lahore. Smog covered the city and made it hard to see far, which is a worry for the millions living there.

Swiss Monitoring Group IQAir Put Delhi’s AQI at 334 and Rated It Hazardous

IQAir, a Swiss air monitoring group, measured Delhi’s Air Quality Index (AQI) at 334, which is in the hazardous category. For comparison, an AQI of up to 50 is considered good, with little or no risk to health.

Why Are There Two Different AQI Readings?

India’s Central Pollution Control Board (CPCB) recorded a higher AQI of 403 at 9 am and rated it severe. The numbers differ because the Swiss and Indian systems use different scales and methods to calculate and classify pollution.

How Did Delhi’s AQI Change This Week?

CPCB readings have climbed steadily since Diwali on Sunday, 8 November. On Friday, 33 of Delhi’s 58 monitoring stations showed severe air, and several readings were above 450. 

1. Tuesday - 299 CPCB AQI
2. Wednesday - 313 CPCB AQI
3. Thursday (4 pm) - 350 CPCB AQI
4. Friday (9 am) - 403 CPCB AQI

Why Did Delhi Become the World’s Most Polluted City?

The steady rise in pollution after Diwali is the main reason Delhi moved ahead. The reference report points to firecrackers and fine particles as the key factors.

Role of Diwali Firecrackers

The Supreme Court had allowed only approved “green” firecrackers on Diwali, and only within fixed time windows. Even so, the AQI kept rising in the days after the festival.

Rise in Fine Particles (PM2.5)

The Centre for Science and Environment (CSE), a Delhi research group, studied PM2.5, which are fine particles small enough to enter the lungs. In the week before Diwali, PM2.5 averaged 236 micrograms per cubic metre of air. That is nearly double the 120 recorded in the same week of 2025. This shows pollution was already high before the festival began.