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Daily Air Quality Index

The Daily Air Quality Index (DAQI) tells you about levels of air pollution. It also provides health advice in the form of recommended actions you may wish to take, according to the level of air pollution. The index is numbered 1-10 and divided into four bands, low (1) to very high (10), to provide detail about air pollution levels in a simple way. This system was recommended by the Committee on Medical Effects of Air Pollutants (COMEAP).

AQ Index Bands

The Daily Air Quality Index Bands are expressed as a value between 1 (Low) – 10 (Very High)

Defra applies the DAQI to its air quality forecasts to tell you what pollution levels are predicted to be the next day. The forecasts are provided to allow you to plan ahead and where relevant, take the recommended action to reduce the effects of air pollution. In addition, York’s latest air pollution monitoring data are displayed using the same index and this tells you what pollution has been like.

The overall air pollution index for a site or region is determined by the highest concentration of five pollutants:

  • Nitrogen Dioxide
  • Sulphur Dioxide
  • Ozone
  • Particles < 2.5µm (PM2.5)
  • Particles < 10µm (PM10)

You should follow the 3 steps below to use the Daily Air Quality Index.

  • Step 1: Determine whether you (or your children) are likely to be at-risk from air pollution.  Further information is provided here.
  • Step 2: If you may be at-risk, and are planning strenuous activity outdoors, check the air pollution forecast.
  • Step 3: Use the health messages below corresponding to the highest forecast level of pollution as a guide.

Air Quality Index Values

Recommended Actions and Health Advice
Air Pollution BandingValueAccompanying health messages for at-risk individuals*Accompanying health messages for the general population
Low (green)1-3Enjoy your usual outdoor activities.Enjoy your usual outdoor activities.
Moderate (orange)4-6Adults and children with lung problems, and adults with heart problems, who experience symptoms, should consider reducing strenuous physical activity, particularly outdoors.Enjoy your usual outdoor activities.
High (red)7-9Adults and children with lung problems, and adults with heart problems, should reduce strenuous physical exertion, particularly outdoors, and particularly if they experience symptoms. People with asthma may find they need to use their reliever inhaler more often. Older people should also reduce physical exertionAnyone experiencing discomfort such as sore eyes, cough or sore throat should consider reducing activity, particularly outdoors.
Very High (purple)10Adults and children with lung problems, adults with heart problems, and older people, should avoid strenuous physical activity. People with asthma may find they need to use their reliever inhaler more often.Reduce physical exertion, particularly outdoors, especially if you experience symptoms such as cough or sore throat.

*Adults and children with heart or lung problems are at greater risk of symptoms. Follow your doctor’s usual advice about exercising and managing your condition. It is possible that very sensitive individuals may experience health effects even on Low air pollution days. Anyone experiencing symptoms should follow the guidance provided