Air Quality Standards
Air quality is measured by comparing against a range of health-effects based standards. This page gives information about what this means.
Standards for air pollution are concentrations over a given time period that are considered to be acceptable in the light of what is known about the effects of each pollutant on health and on the environment. They can also be used as a benchmark to see if air pollution is getting better or worse.
An exceedence of a standard is a period of time (which is defined in each standard) where the concentration is higher than that set down by the standard. In order to make useful comparisons between pollutants, for which the standards may be expressed in terms of different averaging times, the number of days on which an exceedence has been recorded is often reported.
An objective is the target date on which exceedences of a standard must not exceed a specified number. A summary of the current UK Air Quality Objectives is provided here.
Summary of objectives of the National Air Quality Strategy
|Pollutant||Objective||Measured as||To be achieved by|
Authorities in Scotland and Northern Ireland only
|3.25 µg/m3||Running Annual Mean||31 December 2010|
All UK Authorities
|16.5 µg/m3||Running Annual Mean||31 December 2003|
|1,3-Butadiene||2.25 µg/m3||Running Annual Mean||31 December 2003|
Authorities in Scotland only
|10.0 mg/m3||Running 8 Hour Meana||31 December 2003|
|Lead||0.5 µg/m3||Annual Mean||31 December 2004|
|0.25 µg/m3||Annual Mean||31 December 2008|
Not to be exceeded more than 18 times per year
|1 Hour Mean||31 December 2005|
|40 µg/m3||Annual Mean||31 December 2005|
|Nitrogen Oxides**||(V) 30 µg/m3||Annual Mean||31 December 2000|
Not to be exceeded more than 10 times a year
8 hourly running or hour mean
||31 December 2005|
Authorities in Scotland onlyc
Not to be exceeded more than 7 times per year
|Daily Mean||31 December 2010|
|18 µg/m3||Annual Mean||31 December 2010|
All UK authorities
Not to be exceeded more than 35 times per year
|Daily Mean||31 December 2004|
|40 µg/m3||Annual Mean||31 December 2004|
Not to be exceeded more than 35 times per year
|15 Minute Mean||31 December 2005|
Not to be exceeded more than 24 times per year
|1 Hour Mean||31 December 2004|
Not to be exceeded more than 3 times per year
|24 Hour Mean||31 December 2004|
|(V) 20 µg/m3||Annual Mean||31 December 2000|
|(V) 20 µg/m3||Winter Mean (01 October - 31 March)||31 December 2000|
|Poly aromatic hydrocarbonse||
|Annual mean||31 December 2010|
a. The Quality Objective in Scotland has been defined in Regulations as the running 8-hour mean, in practice this is equivalent to the maximum daily running 8-hour mean.
b. Measured using the European gravimetric transfer sampler or equivalent.
c. These 2010 Air Quality Objectives for PM 10 apply in Scotland only, as set out in the Air Quality (Scotland)Amendment Regulations 2002.
d. Measured using the European gravimetric transfer sampler or equivalent.
e. Not included in regulations
µg/m3 - micrograms per cubic metre
mg/m3 - milligrams per cubic metre
*Ozone is not included in the Regulations
** Assuming NOx is taken as NO2
(V) These standards are adopted for the protection of vegetation and ecosystems. All of the remainder are for the protection of human health.
New particle objectives for England, Wales, Northern Ireland and Greater London not included in Regulations
|Region||Objective||Measured as||To be achieved by|
|Greater London||50 µg/m3 not to be exceeded more than 10 times per year||24-hour Mean||31 December 2010|
|Greater London||23 µg/m3||Annual Mean||31 December 2010|
|Greater London||20 µg/m3||Annual Mean||31 December 2015|
|Rest of England, Wales and Northern Ireland||50 µg/m3 not to be exceeded more than 7 times per year||24-hour Mean||31 December 2010|
|Rest of England, Wales and Northern Ireland||20 µg/m3||Annual Mean||31 December 2010|
Index and Bands
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.
- 1-3 (Low)
- 4-6 (Moderate)
- 7-9 (High)
- 10 (Very High)
The overall air pollution index for a site or region is calculated from the highest concentration of five pollutants:
- Nitrogen Dioxide
- Sulphur Dioxide
- Particles PM2.5
- Particles < 10µm (PM10)
Air Pollution Forecasts
Air Quality Forecasts are issued on a regional basis for three different area types:
- In towns and cities near busy roads
- Elsewhere in towns and cities
- In rural areas
Forecasts are based on the prediction of air pollution index for the worst-case of the five pollutants listed above, for each region.
Latest studies report that:
- When air pollution is LOW (1-3) effects are unlikely to be noticed even by those who are sensitive to air pollution.
- When air pollution is MODERATE (4-6) sensitive people may notice mild effects but these are unlikely to need action.
- When air pollution is HIGH (7-9) sensitive people may notice significant effects and may need to take action.
- When air pollution is VERY HIGH (10) effects on sensitive people, described for HIGH pollution, may worsen.
Air pollution can cause short-term health effects to sensitive individuals (people who suffer from heart disease or lung diseases, including asthma). Effects on sensitive people can be reduced by spending less time outdoors. 'Reliever' inhalers should lessen effects on asthma sufferers.
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 on the Additional information on the short-term effects of air pollution page on the Defra UK-AIR website. 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 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 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 on the Defra UK-AIR website.