Live DEFRA air quality data and wildfire smoke alerts for smoke allergy sufferers across the UK. Check the Daily Air Quality Index (DAQI) before leaving home — and know when to close your windows and run your air purifier.
What Is the DEFRA DAQI?
The Daily Air Quality Index (DAQI) is DEFRA's official measure of UK outdoor air pollution. It rates air quality from 1 (Low) to 10 (Very High) across four key pollutants: PM2.5 particulate matter, PM10 coarser particles, nitrogen dioxide (NO₂), and ozone (O₃). For smoke allergy and asthma sufferers, PM2.5 is the most important indicator — it represents the fine particles that penetrate deepest into the lungs. The DAQI is updated hourly at uk-air.defra.gov.uk across a network of monitoring stations throughout England, Scotland, Wales, and Northern Ireland.
When Should You Close Windows and Run Your Purifier?
Close windows and run your MERV 13/16 air purifier on medium speed when: DAQI reaches 4 (Moderate) or above; there is a local wildfire, bonfire, or fireworks event nearby; the Met Office pollen count is High or Very High (if you have hay fever); or you can smell smoke entering your home. Run on maximum speed and keep windows fully closed when: DAQI reaches 7 (High) or above; there is an active wildfire in your region; it is Bonfire Night and the surrounding weekend; or you are experiencing asthma symptoms. At DAQI 9–10 (Very High), vulnerable individuals — asthmatics, COPD patients, children, elderly — should avoid outdoor exposure entirely.
