Most Polluted Countries in the World (2026 Rankings)
Pakistan, Bangladesh, Chad, and the DR Congo top the world's most polluted countries, with fine-particle levels over 10 times the WHO limit. See the 2026 picture.
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Guides on the UV index, air quality, and staying healthy outdoors.
Air QualityLatest
Ozone, NO2, PM2.5, PM10: The Pollutants Behind Your AQI
The pollutants behind your AQI are ozone, nitrogen dioxide, sulfur dioxide, carbon monoxide, and fine and coarse particles. Where each comes from and why.
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How to Check Air Quality Near You in 2026 (5 Ways)
Check air quality near you with AirNow or Europe's EAQI, a PurpleAir sensor map, the World Air Quality Index map, your phone's weather app, or a dedicated app.
AQI Scale Explained: What Is a Good Air Quality Index?
The AQI runs 0 to 500 across six color-coded bands. 0 to 50 (green) is good air, and 101 or higher means sensitive groups should start adjusting outdoor plans.
US AQI vs. EU Air Quality Index: What's the Difference?
The US AQI is a 0 to 500 number covering six pollutants; the European index is a named band from Good to Extremely poor covering five. Same air, different labels.
What UV Index Is Best for Tanning Without Burning?
You can tan from a UV index of about 3 and up, and UV 3 to 5 has the lowest burn risk. But every sun tan is UV damage, and burn speed depends on your skin type.
The UV index scale explained: what 1 to 11+ really means
A plain-language guide to the UV index scale from 1 to 11+, what each band means for your skin, and the simple sun-safety steps to take at every level.