Air Quality Health Index

The 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).

You should follow the 3 step method to use the index.

  • Step 1: Determine whether you (or your children) are likely to be at-risk from air pollution. Information on people who may be affected is provided on the Additional information on the short-term effects of air pollution page. Your doctor may also be able to give you advice.
  • 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.

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,

Boundaries Between Index Points for Each Pollutant

Use the tabs below to view the bandings for each pollutant.

Ozone is based on the running 8-hourly mean.

Band Low Low Low Moderate Moderate Moderate High High High Very High
µg/m³ 0-33 34-66 67-100 101-120 121-140 141-160 161-187 188-213 214-240 241 or more

Health Advice

Generally if you are young and in a good state of health, moderate air pollution levels are unlikely to have any serious short term effects. However, elevated levels and/or long term exposure to air pollution can lead to more serious symptoms and conditions affecting human health. This mainly affects the respiratory and inflammatory systems, but can also lead to more serious conditions such as heart disease and cancer. People with lung or heart conditions may be more susceptible to the effects of air pollution. Effects on sensitive people can be reduced by spending less time outdoors. 'Reliever' inhalers should lessen effects on asthma sufferers.

The table below shows the types of health effects experienced by the most common pollutants at elevated levels:

Pollutant Health effects at very high levels
Nitrogen Dioxide, Sulphur Dioxide, Ozone These gases irritate the airways of the lungs, increasing the symptoms of those suffering from lung diseases
Particles Fine particles can be carried deep into the lungs where they can cause inflammation and a worsening of heart and lung diseases

Recommended actions for at risk individuals according to the air quality health index

Air Pollution Banding Value Accompanying health messages for at-risk groups and the general population
At-risk individuals* General population
Low 1-3 Enjoy your usual outdoor activities. Enjoy your usual outdoor activities.
Moderate 4-6 Adults 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 7-9 Adults 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 exertion. Anyone experiencing discomfort such as sore eyes, cough or sore throat should consider reducing activity, particularly outdoors.
Very High 10 Adults 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 below.