All of the world's 25 most air polluted cities are located in , , and .
in South Africa was recognised as the world’s cleanest city, with an annual average PM2.5 concentration of 1.0 µg/m³.

https://www.newindianexpress.com/nation/2026/Mar/24/global-air-pollution-india-is-sixth-most-polluted-country-pakistan-tops-list-for-2025