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Daily Air Quality Index (DAQI)

In the UK most air pollution information services use the index and banding system approved by the Committee on Medical Effects of Air Pollution Episodes (COMEAP). The system uses 1-10 index divided into four bands to provide more detail about air pollution levels in a simple way, similar to the sun index or pollen index.

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

Air Pollution Forecasts

Air Pollution Forecasts are issued on a regional basis for three different area types:

Forecasts are based on the prediction of air pollution index for the worst-case of the five pollutants listed above, for each region.

How to use the Daily Air Quality Index

Step 1: Determine whether you (or your children) are likely to be at risk from air pollution. Information on groups who may be affected is provided in the Additional information on the short-term effects of air pollution section below. 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 Regional Forecasts page.

Step 3: Use the health messages corresponding to the highest forecast level of pollution as a guide.

Air Pollution Banding Value Accompanying health messages for at-risk individuals* Accompanying health messages for the 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 on the Defra UK-AIR website.

Boundaries Between Index Points for Each Pollutant

The tables below show the bandings for each pollutant.

Ozone

Based on the running 8-hourly mean.

Index 1 2 3 4 5 6 7 8 9 10
Band Low Low Low Moderate Moderate Moderate High High High Very High
µgm-3 0-33 34-66 67-100 101-120 121-140 141-160 161-187 188-213 214-240 241 or more

Nitrogen Dioxide

Based on the hourly mean concentration.

Index 1 2 3 4 5 6 7 8 9 10
Band Low Low Low Moderate Moderate Moderate High High High Very High
µgm-3 0-67 68-134 135-200 201-267 268-334 335-400 401-467 468-534 535-600 601 or more

Sulphur Dioxide

Based on the 15-minute mean concentration.

Index 1 2 3 4 5 6 7 8 9 10
Band Low Low Low Moderate Moderate Moderate High High High Very High
µgm-3 0-88 89-177 178-266 267-354 355-443 444-532 533-710 722-887 888-
1064
1065 or more

PM2.5 Particles

Based on the daily mean concentration for historical data, latest 24 hour running mean for the current day.

Index 1 2 3 4 5 6 7 8 9 10
Band Low Low Low Moderate Moderate Moderate High High High Very High
µgm-3 0-11 12-23 24-35 36-41 42-47 48-53 54-58 59-64 65-70 71 or more

PM10 Particles

Based on the daily mean concentration for historical data, latest 24 hour running mean for the current day.

Index 1 2 3 4 5 6 7 8 9 10
Band Low Low Low Moderate Moderate Moderate High High High Very High
µgm-3 0-16 17-33 34-50 51-58 59-66 67-75 76-83 84-91 91-100 101 or more

Additional Information on the Short-Term Effects of Air Pollution

The air quality index (DAQI) has been developed to provide advice on expected levels of air pollution. In addition, information on the short-term effects on health that might be expected to occur at the different bands of the index (Low, Moderate, High, Very High) is provided. It is possible that very sensitive individuals may experience health effects even on Low air pollution days. This advice applies to anyone experiencing symptoms.

Short-term effects of air pollution on health

Air pollution has a range of effects on health. However, air pollution in the UK does not rise to levels at which people need to make major changes to their habits to avoid exposure; nobody need fear going outdoors.

Action that can be taken

When levels of air pollution increase it would be sensible for those who have noticed that they are affected to limit their exposure to air pollutants. This does not mean staying indoors, but reducing levels of exercise outdoors would be reasonable.