Daily Air Quality Index

The 'Daily Air Quality Index' depends on pollutant concentrations averaged over specified periods. These averaging periods were specifically selected by the 'Committee on the Medical Effects of Air Pollutants' (COMEAP) on the basis of epidemiology studies concerning the short-term impacts of air pollution. With these specifications the air quality index is inherently a 'daily' index and it is not possible to display values representing shorter time periods (for example 3 hourly) without distorting the intended meaning of the index.

The daily air quality index comes in three parts and includes additional advice for susceptible individuals, alongside advice for the general population:

  1. Instructions on how the index should be used
  2. The short-term health effects of air pollution and action that can be taken to reduce impacts
  3. Health advice linked to each band to accompany the air quality index

These are detailed below:

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 can be found in the Additional information on the effects of air pollution section. 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 corresponding to the highest forecast level of pollution as a guide.

Additional information on the short-term effects of air pollution

The daily 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.

Adults or children with lung or heart conditions: It is known that, when levels of air pollutants rise, adults suffering from heart conditions, and adults and children with lung conditions, are at increased risk of becoming ill and needing treatment. Only a minority of those who suffer from these conditions are likely to be affected and it is not possible to predict in advance who will be affected. Some people are aware that air pollution affects their health: adults and children with asthma may notice that they need to increase their use of inhaled reliever medication on days when levels of air pollution are higher than average.

Older people are more likely to suffer from heart and lung conditions than young people and so it makes good sense for them to be aware of current air pollution conditions.

The general population: At very high levels of air pollution, some people may experience a sore or dry throat, sore eyes or, in some cases, a tickly cough even in healthy individuals.

Children need not be kept from school or prevented from taking part in games. Children with asthma may notice that they need to increase their use of reliever medications on days when levels of air pollution are higher than average.

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.

Older people and those with heart and lung conditions might avoid exertion on High pollution days.

Adults and children with asthma should check that they are taking their medication as advised by their health practitioner and may notice that they need to increase their use of inhaled reliever medication.

Adults with heart and circulatory conditions should not modify their treatment schedules on the basis of advice provided by the air quality index: such modification should only be made on a health practitioner's advice.

Some athletes, even if they are not asthmatic, may notice that they find their performance less good than expected when levels of a certain air pollutant (ground level ozone) are High, and they may notice that they find deep breathing causes some discomfort in the chest: This might be expected in summer on days when ground level ozone levels are raised. This does not mean that they are in danger but it would be sensible for them to limit their activities on such days.

Health advice to accompany the Daily Air Quality Index

Air pollution banding Value Accompanying health messages for at-risk groups and the general population
At-risk individuals* General population
Low
level 1 level 2 level 3
1-3 Enjoy your usual outdoor activities. Enjoy your usual outdoor activities.
Moderate
level 4 level 5 level 6
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
level 7 level 8 level 9
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
level 10
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 in the Additional information on the effects of air pollution section.

Daily Air Quality Index

The bandings for the Daily Air Quality Index are detailed in the table below:

Bandings for the Daily Air Quality Index
Band Index Ozone Nitrogen Dioxide Sulphur Dioxide PM2.5 Particles PM10 Particles
Running 8 hourly mean Hourly mean 15 minute mean 24 hour mean 24 hour mean
µg m−3 µg m−3 µg m−3 µg m−3 µg m−3
Low level 1 0-33 0-67 0-88 0-11 0-16
level 2 34-66 68-134 89-177 12-23 17-33
level 3 67-100 135-200 178-266 24-35 34-50
Moderate level 4 101-120 201-267 267-354 36-41 51-58
level 5 121-140 268-334 355-443 42-47 59-66
level 6 141-160 335-400 444-532 48-53 67-75
High level 7 161-187 401-467 533-710 54-58 76-83
level 8 188-213 468-534 711-887 59-64 84-91
level 9 214-240 535-600 888-1064 65-70 92-100
Very High level 10 241 or more 601 or more 1065 or more 71 or more 101 or more

For more information about the Daily Air Quality Index please take a look at the science background to the Met Office Air Quality Forecast.

Last updated: 22 April 2014