The World AQI Indices are based on the US EPA (United States Environmental Protection Agency) Scale, latest 24 hour running mean for the current day.

WORLD (US EPA) AQI PM2.5 Good Moderate Unhealthy for Sensitive Groups Unhealthy Very Unhealthy Hazardous
Range 0-50 51-100 101-150 151-200 201-300 300
µg/m³ 0-12 12-35 35-55 55-150 150-250 250
The Defra (UK Government Department for Environment and Rural Affairs) DAQI Indices are based on the daily mean concentration for historical data, latest 24 hour running mean for the current day.

UK DAQI Low Low Low Moderate Moderate Moderate High High High Very High
Band 1 2 3 4 5 6 7 8 9 10
PM2.5 µg/m³ 0-11 12-23 24-35 36-41 42-47 48-53 54-58 59-64 65-70 71 or more
PM10 µg/m³ 0-16 17-33 34-50 51-58 59-66 67-75 76-83 84-91 92-100 101 or more
The European CAQI (Common Air Quality Index) Indices are based on the daily mean concentration for historical data, latest 24 hour running mean for the current day.

Europe (CAQI) Very Low Low Medium High Very High
Range 0-25 25-50 50-75 75-100 100 or more
PM2.5 µg/m³ 0-15 15-30 30-55 55-110 110 or more
PM10 µg/m³ 0-25 25-50 50-90 90-180 180 or more