How it works
The 1–10 scale
We use the UK government's Daily Air Quality Index. Lower is better.
Good
Air is clean. A great time to be outside.
Moderate
Fine for most people. If you have asthma, take it a little easier.
Poor
Cut down on hard exercise outdoors, especially near busy roads.
Very poor
Avoid strenuous activity outside. Keep inhalers close.
Where the data comes from
Readings come live from the London Air Quality Network, run by Imperial College London's Environmental Research Group. It's the scientific network London's boroughs use. Stations measure pollution every hour, and we refresh every 15 minutes.
The headline for London is the typical (middle) reading across all stations reporting. Each dot's level is set by its worst pollutant.
Postcode search uses postcodes.io. This site gives general guidance, not medical advice.