Air quality
What is the air like where you are, right now?
Type a city or zip code for the US EPA Air Quality Index, the pollutants behind it, and who should take care today.
Largest US cities right now
The 12 most populous US cities (2020 Census), live US EPA index, refreshed hourly.
How the index works
The US EPA Air Quality Index runs from 0 to 500 in six bands. It is driven by the worst of the measured pollutants at that hour; the pollutant cards show each one against the World Health Organization’s guideline, which is stricter than the index for PM2.5 and NO₂.
Where the data comes from
- Readings and the seven-day history come from the Google Air Quality API, which blends government monitors, satellite data and models; they update hourly.
- Bands, names and colours are the US EPA’s own.
- Guidelines are the WHO 2021 air quality guidelines: PM2.5 5 µg/m³ and PM10 15 µg/m³ (annual), ozone 60 µg/m³ (peak season), NO₂ 10 µg/m³ (annual).