Skip to content
NumberReels

Public interestEpisode 30Leaderboard0:31

Counting down the world's most polluted cities

Annual average PM2.5, 2025 (µg/m³)

Guess the number before you watch

Guess the number

Guess the number: micrograms of PM2.5 per m³ in the worst city

100 µg/m³
0 µg/m³200 µg/m³
0:00 / 0:31

Source: IQAir 2025 World Air Quality Report, PM2.5

Part of The planet in numbers

Keep watching in the feed
The numbers
Answer at 0:28

15 on the list. The figures appear here once the clip gives the answer away.

Narration

Follows the clip · tap a line to jump

Runs 0:31.

How to read this chart: A long ranked list scrolls past, each row with a bar on one shared scale, and the number one entry is held back until the end. The rank number is the point, and entries next to each other are often nearly tied. More on leaderboard charts.

The takeaway

13 of the 15 most polluted cities are in India or Pakistan.

The data

The numbers

This clip asks you to guess first.

The numbers open when the clip reaches its answer, so they can't give it away.

Source: IQAir 2025 World Air Quality Report, PM2.5.

What the numbers show

IQAir's 2025 World Air Quality Report, published on 24 March 2026, ranked 9,446 cities in 143 countries and territories by annual average PM2.5, the fine particles small enough to reach deep into the lungs. The most polluted was Loni, in Uttar Pradesh, India, at 112.5 µg/m³, up nearly 23% from 2024.

Hotan in China (109.6) came second and Byrnihat in India (101.1) third, with Delhi (99.6) and Faisalabad in Pakistan (98.8) completing the top five. Thirteen of the 15 cities in this countdown are in India or Pakistan; the other two, Hotan and Kashgar, are in China.

For scale, the WHO's annual PM2.5 guideline is 5 µg/m³, so Loni's average is more than 22 times higher. IQAir reports that only 14% of the cities it tracked met that guideline in 2025, down from 17% the year before.

Numbers of the week, in your inbox

One email every Monday: last week’s clips, the number behind each, and what’s coming next. No spam, unsubscribe anytime.

Transcript

  1. 112.5 micrograms of PM2.5 per cubic metre. That's the world's worst city. Guess which.

  2. The countdown opens in the eighties with Madhyamgram and Lodhran. Then Lahore at 88.9, Delhi at 99.6, and Byrnihat at 101.1. Only two cities are worse, and Hotan, in China, is one of them. Thirteen of the fifteen are in India or Pakistan.

  3. Follow for daily stats from NumberReels, and tell us which stat you'd like to see next.

Source & method

Support the project

Public interest

More like this