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. Use the links below to jump to specific content.
- Air Quality Standards
- Air Pollution Information Service
- Index Points and Bandings
- Additional information about the Short-Term Effects of Air Pollution
Air Quality Standards and Objectives
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.
The objectives adopted in Scotland are based on the Air Quality Standards (Scotland) Regulations 2007 for the purpose of Local Air Quality Management.
These have been adopted in order to:
a) transpose Directive 2004/107/EC of the European Parliament and of the Council of 15 December 2004 relating to arsenic, cadmium, mercury, nickel and polycyclic aromatic hydrocarbons in ambient air (also known as the Fourth Daughter Directive); and
b) replace the existing Air Quality Limit Values (Scotland) Regulations 2003 to consolidate the provisions of those Regulations so that, in addition to the Fourth Daughter Directive, the new Regulations also transpose the following Directives:
- Air Quality Framework Directive (96/62/EC);
- First Daughter Directive (1999/30/EC);
- Second Daughter Directive (2000/69/EC); and
- Third Daughter Directive (2002/3/EC).
A summary of the current UK Air Quality Objectives is provided here.
Summary of objectives of the National Air Quality Strategy
| Pollutant | Air Quality Objective | To be achieved by | |
|---|---|---|---|
| Concentration | Measured as | ||
| Benzene | |||
| All UK authorities | 16.25 µg m-3 | Running annual mean | 31 December 2003 |
| Authorities in Scotland and N. Ireland | 3.25 µg m-3 | Running annual mean | 31 December 2010 |
| 1,3-Butadiene | 2.25 µg m-3 | Running annual mean | 31 December 2003 |
| Carbon Monoxide | |||
| Authorities in Scotland Only | 10.0 mg m-3 | Running 8-hour mean | 31 December 2003 |
| Lead | 0.5 µg m-3 | Annual mean | 31 December 2004 |
| 0.25 µg m-3 | Annual mean | 31 December 2008 | |
| Nitrogen Dioxide | 200 µg m-3 not to be exceeded more than 18 times a year | 1-hour mean | 31 December 2005 |
| 40 µg m-3 | Annual mean | 31 December 2005 | |
| Particles (PM10) (gravimetric) | |||
| All authorities | 50 µg m-3, not to be exceeded more than 35 times a year | 24 Hour mean | 31 December 2004 |
| 40 µg m-3 | Annual mean | 31 December 2004 | |
| Scotland Only | 50 µg m-3, not to be exceeded more than 7 times a year | 24 Hour mean | 31 December 2010 |
| 18 µg m-3 | Annual mean | 31 December 2010 | |
| Particles (PM2.5) (gravimetric) * | 25 µg m-3 (target) | Annual mean | 2020 |
| All UK authorities | 15% cut in urban background exposure | Annual mean | 2010 - 2020 |
| Authorities in Scotland Only | 12 µg m-3 (limit) | Annual mean | 2010 |
| Sulphur dioxide | 350 µg m-3, not to be exceeded more than 24 times a year | 1-hour mean | 31 December 2004 |
| 125 µg m-3, not to be exceeded more than 3 times a year | 24-hour mean | 31 December 2004 | |
| 266 µg m-3, not to be exceeded more than 35 times a year | 15-minute mean | 31 December 2005 | |
| PAH * | 0.25 ng m-3 | Annual mean | 31 December 2010 |
| Ozone * | 100 µg m-3 not to be exceeded more than 10 times a year | 8 hourly running or hourly mean* | 31 December 2005 |
* not included in regulations at present
Shaded data shows new objectives
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UK Air Quality Objectives for protection of vegetation and ecosystems - July 2007
| Pollutant | Air Quality Objective | To be achieved by | |
|---|---|---|---|
| Concentration | Measured as | ||
| Oxides of Nitrogen (for protection of vegetation & ecosystems) * | 30 µg m-3 | Annual mean | 31 December 2000 |
| Sulphur dioxide (for protection of vegetation & ecosystems) * | 20 µg m-3 20 µg m-3 |
Annual mean Winter Average (Oct - Mar) |
31 December 2000 |
| Ozone * | 18000 µg m-3.h | AOT40+, calculated from 1h values May-July. Mean of 5 years, starting 2010 | 01 January 2010 |
* not included in regulations at present
+ AOT 40 is the sum of the differences between hourly concentrations greater han 80 µg m-3 (=40ppb) and 80
µg m-3, over a given period using only the 1-hour averages measured between 0800 and 2000.
Shaded data shows new objectives
Air Pollution Information Service
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
- Ozone
- Particles 2.5µm (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.
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 at Additional information on the short-term effects of air pollution 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 for cast for the Highlands, North East Scotland, Central Scotland and the Scottish Borders.
Step 3: Use the health messages corresponding to the highest forecast level of pollution as a guide.
Air Pollution Bandings and Health Impacts
| 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 at Additional information on the short-term effects of air pollution below.
Boundaries Between Index Points for Each Pollutant
| Band | Index | Ozone | Nitrogen Dioxide | Sulphur Dioxide | PM2.5 Particles | PM10 Particles | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Running 8 hourly mean | hourly mean | 15 minute mean | 24 hour running mean | 24 hour running mean | |||||||
| µgm-3 | µgm-3 | µgm-3 | µgm-3 | µgm-3 | |||||||
| Low | |||||||||||
| 1 | 0-33 | 0-67 | 0-88 | 0-11 | 0-16 | ||||||
| 2 | 34-66 | 68-134 | 89-177 | 12-23 | 17-33 | ||||||
| 3 | 67-100 | 135-200 | 178-266 | 24-35 | 34-50 | ||||||
| Moderate | |||||||||||
| 4 | 101-120 | 201-267 | 267-354 | 36-41 | 51-58 | ||||||
| 5 | 121-140 | 268-334 | 355-443 | 42-47 | 59-66 | ||||||
| 6 | 141-160 | 335-400 | 444-532 | 48-53 | 67-75 | ||||||
| High | |||||||||||
| 7 | 161-187 | 401-467 | 533-710 | 54-58 | 76-83 | ||||||
| 8 | 188-213 | 468-534 | 711-887 | 59-64 | 84-91 | ||||||
| 9 | 214-240 | 535-600 | 888-1064 | 65-70 | 92-100 | ||||||
| Very High | |||||||||||
| 10 | 241 or more |
601 or more |
1065 or more |
71 or more |
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.
- Adults and 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 medication 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.
