Last update:

31st January 2008

Quick links:

What is air pollution?

What causes air pollution?

Air quality in the South West

Sources of emissions in the South West

South West air quality monitoring map

Air Quality Strategy

UK air quality maps

National air quality trends

Local Air Quality Management

A more local perspective

• Cornwall air quality
• Devon air quality
• Somerset Air Quality
• Dorset air quality
• Bath & North East Somerset, Bristol and Gloucestershire
• Wiltshire air quality

Air quality and health

Action to reduce air pollution

Carbon dioxide

Acid rain

Light

Noise

Releases to air

Climate change

Health

Transport

Useful websites:

Defra air quality pages

Air Quality Strategy

Air Quality Archive

National Atmosphereic Emissions Inventory (NAEI)

DEFRA stategy consultation

Expert Panel on Air Quality Standards

NETCEN

Sustainable Development's indicators

Department of Health air quality information

Cornwall Air Quality Forum

Earth Observatory

Environment Agency

National Society for Clean Air

UK air emissions database

Air Quality

What's new on this page...

• Local Air Quality Management Areas designated in the South West 2008
• Air quality indicator for sustainable development 2007 (provisional results)
• Air quality in the South West 2006
• Ground level ozone in the South West 2006

Good air quality is critical to people's good health and the condition of the region's wildlife, habitats and built environment. Sources of emissions include energy generators, waste, industry, transport and agriculture.

What is air pollution?

Air pollution comes from many sources and different types of pollutants impact on our environment and health.

There are many different types of air pollutant. These pollutants have different effects on the environment and on our health. Some, directly because they are harmful chemicals and others because they can react together to produce harmful chemicals. Other pollutants or pollutant combinations upset the natural balance of acidity and nitrogen in the environment which can affect the diversity of species in sensitive areas. Other pollutants can contribute to changing global conditions and potentially give rise to dramatic changes in climate and sea level.

More information about air pollution, its causes and effects are available from the National Atmospheric Emissions Inventory (NAEI) and the Air Quality Archive

Air quality indicator for sustainable development 2007 (provisional results)

The air quality indicator is one of the 68 indicators of the Government’s Sustainable Development Strategy. It measures annual levels of pollution from particulates (PM10) and ozone (O3), the two pollutants thought to have the greatest health impacts, as well as the number of days on which levels of any one of a basket of five pollutants were ‘moderate or higher’.

The main results are:

• Urban background particulate levels averaged 21 microgrammes per cubic metre (µg m-3) in 2007 compared to 24µg m-3 in 2006. These levels have fluctuated in the last 5 years, although there has been an overall decreasing trend since 1993, the first year for which data were available.
• Roadside particulate levels averaged 31 µg m-3 in 2007 compared to 32 µg m-3 in 2006. There has been a general downward trend since monitoring started in 1997, although this decline has slowed since 2001.
• Rural ozone levels averaged 67 µg m-3 in 2007 compared to 74 µg m-3 in 2006 and 68 µg m-3 in 1993. There is no clear long term trend.
• Urban background ozone levels averaged 57 µg m-3 in 2007 compared to 61 µg m-3 in 2006 and 44 µg m-3 in 1992. These levels have shown an overall increasing long term trend since 1992, the first year for which data were available.
• In urban areas, air pollution in 2007 was recorded as moderate or higher on 23 days on average per site, compared with 41 days in 2006, and 59 days in 1993. This series has reflected a high degree of year-on-year variability over time, and this has again been apparent for 2007.
• In rural areas, air pollution in 2007 was moderate or higher for 26 days on average per site, compared with 56 in 2006. This figure has also varied significantly over time.
• These results are provisional and are therefore subject to change. Final results we be available in the spring.

Background

An air quality “headline” indicator was introduced in 1999 in support of the UK Sustainable Development Strategy. When this strategy was updated in 2005, a new air quality indicator was included, better reflecting the effects on health of long term exposure to lower levels of pollution. The indicator is split into two parts covering; (a) annual exposure to pollutants and (b) the number of days when levels pollutants are moderate or higher.

Days with moderate or higher air pollution

There is no clear trend in the number of either urban or rural pollution days, due to the effects of variability in weather patterns from year to year.

Carbon monoxide and nitrogen dioxide have very rarely reached moderate or higher levels since the urban index began in 1992.

Causes of air pollution in urban sites

Three of the five pollutants, ozone, particulates and sulphur dioxide caused over 99% of the pollution days, either separately or in combination with each other. Between 1993 and 2007, the average number of days of pollution at urban sites caused by particulates, solely or in combination with other pollutants, fell from an average per site of about 43 days to 11 days per year.

The average number of pollution days at urban sites caused by sulphur dioxide, solely or in combination with other pollutants, was 20 days per site in 1993. In 2007 sulphur dioxide did not cause any pollution days, either solely or in combinations with other pollutants.

Ozone causes the great majority of pollution days in rural areas. Since 1999 it has also caused more days of poor air quality in urban areas than particulates have, as pollution by particulates has declined. The number of days caused by ozone pollution has fluctuated in both rural and urban areas, with no clear overall trend. The hot summers in 1999, 2003 and 2006 led to the greatest number of days of moderate or higher ozone pollution since this series began in 1987. A proportion of the ozone experienced in the UK originates from releases of pollution that are blown over from mainland Europe.

The series can be volatile from one year to the next, reflecting the variability in levels of ozone, more of which is produced in hot, sunny weather, as was the case during 2003 and 2006.

Air quality in the South West

Government air quality statistics show that air quality in the South West is generally good with low levels of sulphur, nitrogen dioxides and particulates in comparison to the rest of England. However, pockets of poor air quality exist in the region, especially within large urban industrial areas such as Bristol.

Nationally, in 2006 there was an average of 41 days of moderate or higher air pollution in urban areas (up from 22 days in 2005) and 57 days in rural areas (up from 40 days in 2005).

It is not possible to provide regional averages because there are too few sites in some regions. Instead, Plymouth Centre and Bristol Centre have been chosen as representative urban sites in the region, whilst Yarner Wood (Devon) and Somerton (Somerset) are representative rural sites.

Data was not available for Bristol City and Plymouth City in 2006. However, monitoring at the two rural sites in the region revealed that Yarner Wood experienced 73 days of moderate or higher air pollution (up from 35 in 2005) whilst Somerton had 43 (up from 34 in 2005).

The average number of days with moderate or higher air pollution has generally decreased significantly in urban areas since 1993, largely because of a reduction in particles and sulphur dioxide. In rural areas, where ozone is the main cause of pollution, there has been no overall trend.

From year to year there can be significant variations caused by the weather, particularly for ozone, more of which is created in hot sunny weather. For example, the hot summer of 2003 was a major factor in the high figures for that year.

Air Quality - days when air pollution is moderate or higher in the South West with national comparison 1987 - 2006

Click to enlarge

Source: Defra & Netcen (2007)

Instances of moderate and high air pollution in the region have occurred due to high levels of ground level ozone (as can be seen in the ozone map and the graph below). Ozone is formed by chemical reactions between oxides of nitrogen and hydrocarbons in the lower layers of the atmosphere. Concentrations tend to be highest in the southern regions, near the coast and at high altitudes because high temperatures and sunshine levels promote the photochemical reactions that generate ground level ozone. Urban areas tend to have lower levels of ground level ozone due to higher levels of nitric oxide than rural areas, which can destroy ozone.

High levels of ground level ozone can be detrimental to health, causing irritation of eyes, nose and lungs. As a result, Defra's provisional health objective is that the daily maximum 8 hour running mean should not exceed a concentration of 50 parts per billion on more than 10 days a year at any site by 2005. As can be seen in the graph below, there has been no clear trend in the average annual concentration of ground level ozone over the last 20 years both nationally. The 6 Monitoring sites in the South West also show no clear trend, however, all showed a significant decline between 2003 and 2005 and an increase between 2005 and 2006.

Ozone - days exceeding maximum 8 hour running mean in the South West with national comparison 1987 - 2006

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Source: Netcen & Defra (2007)

Sources of air pollution in the South West

More information about carbon dioxide emissions in the South West is available here.

Air quality monitoring in the South West

There are eight automatic air quality monitoring sites in the South West (more information about which is available from Defra). Click on any of these sites on the map below to view:

• Last hour's data
• Weekly graphs
• Site information (description, location, photos)
• UK background concentration data

Air quality monitoring sites in the South West:

Detailed air quality statistics can also be downloaded by local authority area. Click on a local authority area in the map below to view air quality strategy pollutant statistics. (click to enlarge and access more data from South West monitoring sites)

NB. The Bristol Centre site has now closed

Source: Air Quality Archive

Air quality in South west local authority areas - air quality strategy pollutants

The UK National Air Quality Archive contains detailed statistics for local authorities in terms of individual pollutants or Air Quality Strategy pollutants. Click here to go to this web-based search facility

Local air quality management

Since 1997 local authorities in the UK have been carrying out a review and assessment of air quality in their area. The aim of the review is to make sure that the national air quality objectives will be achieved. If a local authority finds any places where the objectives are not likely to be achieved, it must declare an Air Quality Management Area there and put together a plan to improve the air quality - a Local Air Quality Action Plan.

28 Air Quality Management Areas (AQMAs) have been designated in 18 local authorities in the region:

• The 5 AQMAs designated in Exeter City in previous years have now been amalgomated into one
• The 5 AQMAs designated in Salisbury city in previous years have now been amalgomated into one
• 26 of the 28 AQMAs (92%) in the region are established due to high levels of nitrogen dioxide (NO2) as a result of traffic
• 3 AQMAs (10%) are established to monitor both nitrogen dioxide and particulate matter (Bristol, Crediton and Bradford-on-Tone)
• 1 AQMA is established to monitor benzene (Plymouth)
• 1 AQMA is established to monitor sulphur dioxide (Sedgemoor)

Full details of AQMAs and links to further information are available below.

Emissions maps

Air quality in Cornwall

Work carried out for the Cornwall Air Quality Strategy, has highlighted that air quality in the county is generally good due to:

• Atlantic / south west winds
• Pro active local authorities / Cornwall Air Quality Fourm
• Use of renewable energy
• Only one border so fewer external effects and greater impacts of local initiatives
• Relatively low population density
• Plenty of open space
• Less pollution from heating due to new fuels
• Insultation to houses
• Carbon sink (biomass 'v' population)
• Low level of industrial emissions
• Less traffic than other parts of the country

However, air pollution can be a problem in some parts of the county, particularly in relation to:

• Low level ozone
• Particulates (from natural and industrial sources such as china clay dust)
• Light pollution
• Greenhouse gases
• Transboundary ozone
• Radon (especially in West Cornwall)
• Airborne arsenic, cadmium and other toxic heavt materials (especially in West Cornwall)
• Car emissions / fumes such as CO2, NOx and PM10.

More information about air quality in Cornwall can be found on the Cornwall Air Quality Forum - a partnership established in 1995 with representatives from five of the District Councils in the county, Cornwall County Council, the Environment Agency and Cornwall College.

Facilities on the Cornwall Air Quality Forum website

More information about air quality in each of the Cornwall districts is available on the following local authority websites (online content varies):

• Cornwall County Council - better air quality for Cornwall
• Carrick District Council
• Kerrier District Council
• North Cornwall District Council / North Cornwall District Council's Air Quality data
• Penwith District Council
• Restormel Borough Council

Air quality in Devon

• Devon environmental protection group
• Exeter City Council
• Plymouth City Council
• East Devon District Council / East Devon Local Air Quality Management (2003)
• Mid Devon District Council
• North Devon District Council / North Devon Local Air Quality Management
• South Hams District Council / South Hams Air Quality Strategy
• Teinbridge District Council
• Torbay District Council
• Torridge District Council / Torridge Local Air Quality Management
• West Devon Borough Council

Air quality in Somerset

• Somerset Local Air Quality Sub Group
• Mendip District Council
• Sedgemoor District Council
• South Somerset District Council
• Taunton Deane Borough Council
• West Somerset District Council

Air quality in Dorset

• Bournemouth Borough Council
• East Dorset District Council
• North Dorset District Council
• West Dorset District Council
• Weymouth District Council / Weymouth Air Quality Strategy

Air quality in Bath & NE Somerset, Bristol and Gloucestershire

The former Avon area is made up of four unitary authorities, each of which has identified locations where pollutant concentrations may exceed national targets in future. Traffic emissions are responsible for the elevated concentrations at such pollution ‘hot spots’, and reductions in traffic emissions will be necessary to improve local air quality across the former-Avon area.

• Bristol Air Quality Data website - local air quality & emissions readings
• CUBA (Councils that Used to Be Avon) environmental protection group
• Gloucestershire pollution group
• Bath and NE Somerset
• Bristol City Council
• Gloucestershire County Council / Gloucestershire Air Quality Management
• Cheltenham Borough Council
• Gloucester City Council
• South Gloucestershire Council
• Stroud District Council
• Tewksbury Borough Council

Air quality in Wiltshire

• Wiltshire local air quality management sub-group
• Kennet District Council
• North Wiltshire District Council
• Salisbury District Council
• Swindon Borough Council
• West Wiltshire District Council

National air quality trends

Air quality - days when air pollution was moderate or higher: is one of the Government's 15 Headline Indicators of Sustainable Development. It presents trends for annual levels of particulate and ozone pollution, the two pollutants thought to have the greatest health impacts, as well as the number of days on which levels of any one of a basket of five pollutants were ‘moderate or higher’.

Data for 2005 indicates that:

• Annual average urban background particulate (PM 10) levels remained unchanged at 22 microgrammes per cubic metre (µg m-3) from 2004 to 2005, generally showing a decreasing trend from 36 µg m-3 in 1993.
• Rural ozone levels (measured as the daily maximum 8-hour running mean) averaged 70 µg m-3 in 2005 compared to 73 µg m-3 in 2004 and 68 µg m-3 in 1993. There is no clear long term trend.
• Urban background ozone levels were 57 µg m-3 in 2005, the same as in 2004 and have generally increased from 42 µg m-3 since 1993.
• In urban areas in 2005, air pollution was recorded as moderate or higher on 22 days on average per site, compared with 23 days in 2004, 50 days in 2003, and 59 days in 1993, reflecting a general decline in urban pollution.
• In rural areas, air pollution in 2005 was moderate or higher for 40 days on average per site, compared with 44 in 2004, and 64 in 2003. The number of days has fluctuated between 21 days in 1987 and the 2003 figure of 64 days, showing little overall trend.

Days when air pollution is moderate or higher in the united kingdom: 1987-2005

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Source: NETCEN and Defra (2006)

UK Air quality strategy

The Air Quality Strategy for England, Scotland, Wales and Northern Ireland (2000) sets out the government's plan to improve and protect ambient medium-term air quality in the UK.

The objectives in the Strategy have been set with regard to the scientific and medical evidence on the effects of particular pollutants on health. The objectives for the pollutants covered in the Strategy are shown in the table below:

Summary of national objectives of the Air Quality Strategy

Source: Defra (2003)

Local authorities in England, Scotland and Wales are required to review and assess air quality in their area against the objectives specified for each pollutant in their respective Air Quality Standards regulations. Northern Ireland has a separate environmental legislative code, and its District Councils have voluntarily engaged in the air quality review and assessment process.

Particulate matter in the UK

Particulate Matter in the UK (2005) is a new report from the Air Quality Expert Group (AQEG) following on from the Air Quality Strategy for England, Scotland, Wales and Northern Ireland.

The total emissions of primary PM10 in the UK fell between 1970 and 2001, mainly due to reductions in emissions from domestic heating, energy production and from industrial combustion. This trend is similar to that experienced in mainland Europe. During 1990 to 2001, emissions of primary PM10 in the UK fell by 42% compared with 23% in Germany, 13% in France and 39% in Sweden.

AQEG expect emissions to fall by a further 28% by 2010, mainly from reductions in power station and road transport emissions, but to level off between 2010 and 2020. However, the reduction may not be as great as this if the recent growth in the numbers of diesel cars on the road continues. The Department for Transport now expects that more diesel cars will be sold in the UK than it had previously forecast. Emissions of particulate matter from diesel cars are greater than those from petrol cars.

In terms of the future, the report finds it is clear that, although road traffic emissions are a major source of particulate matter near to roads, the regional contribution to particulate matter is substantial. Controlling background particulate matter must, therefore, be a central part of any UK strategy to control exposure to particulate matter.

In addition, because there is no known safe level for exposure to particulate matter, it is not appropriate to rely solely on the use of air quality objectives. They focus attention on ‘hotspots’ – places where the pollutant concentration is high, for example close to busy roads, but where relatively few people tend to live. Controls on particulate matter must focus more widely than at present.

This report gives a full background into particulate matter in the UK as well as how and where PM10 is monitored, what leads to high concentrations, PM10 and health, concentrations outside of monitoring sites, future trends and recommendations.

What causes air pollution?

In both developed and rapidly industrialising countries, the major historic air pollution problem has historically been high levels of smoke and sulphur dioixide arising from the combustion of sulphur-containing fossil fuels such as coal for domestic and industrial purpose.

In more recent years, however, the major threat to clean air is posed by traffic emissions. Petrol and diesel-engined motor vehicles emit a wide variety of pollutants, principally carbon monoxide (CO), oxides of nitrogen (NOx), volatile organic compounds (VOCs) and particulates (PM10), which have an increasing impact on urban air quality. According to Defra, the main sources of air pollution are:

• Road transport is the main source of nitrogen dioxide and carbon monoxide.
• Power stations and other industrial sources also produce nitrogen dioxide. Industry is the main source of sulphur dioxide.
• Particles come from many sources, including road transport, power stations and other industry. The burning of wood or coal for home heating can also be an important source of sulphur dioxide and particles.
• Ground level ozone is not emitted directly from any source. Instead it is formed when sunlight acts on nitrogen dioxide and other atmospheric substances close to the ground. The pollutants that cause ground level ozone come from a range of sources, including petrol and other fuels. Ground level ozone is different to the ozone layer, which is affected by ozone depleting substances, such as CFCs, that have been released into the atmosphere.

Air pollution levels vary from area to area and from day to day. Levels of pollution can be influenced by a number of things:

• Local landscape features and surroundings
• Local and regional sources of pollution
• Seasonal variations and prevailing weather conditions.

The following locations and weather conditions might lead to higher or lower levels of pollution

Source: Defra (2002)

More information about the causes of air pollution can be found on the Air Quality Archive's website.

Impacts of air pollution

Air pollutants can have significant impacts on the environment and our health (see pages on acid rain, releases to air & greenhouse gases and climate change). The following table summarises the key impacts according to pollutant:

Air pollutant types (including greenhouse gases) and their impacts

1 - Ozone is produced by photochemical reactions involving volatile organic compounds and nitrogen oxides in the lower atmosphere.
2 - Includes heavy metals and Persistent Organic Pollutants (POPs).

Source: Netcen, published by Defra (2003)

Air pollution and health

A comprehensive leaflet detailing the impacts of air pollution on health is available from Defra (hard copy available free of charge).

According to this leaflet, if your health is good, the levels of air pollution we usually experience in the UK are unlikely to have any serious short-term effects. But on the rare occasions when air pollution levels are high, some people may feel eye irritation, others may start to cough, and some may find breathing painful.

People with lung diseases or heart conditions are at greater risk, especially if they are elderly. Daily changes in air pollution trigger increased admissions to hospital and contribute to the premature death of those who are seriously ill.

The table below describes how the health of people who are sensitive to air pollutants might be affected by pollution at the different levels or bands (people with heart conditions or severe lung diseases (such as chronic bronchitis or emphysema) also be more sensitive to changes in air pollution than the descriptions:

Impacts of air pollutants on people

Source: Defra (2002)

The impacts of key air pollutants on health

Source: Air Quality Archive

More information about air quality and health is available from the Department of Health, including a free air pollution and health information pack (by post).

More information about the environment & it's impact on health can be found here.

How you can help to reduce air pollution

The Air Quality Strategy sets the framework for local action to reduce pollution and Local authorities are monitoring and assessesing their air quality and preparing action plans to help deal with pollution hot-spots. The Environment Agency and local authorities are monitoring and regulating emissions from industry. The European Union and other international organisations are acting to reduce global pollution. The Government and devolved administrations have introduced a wide range of measures, which have substantially cut harmful emissions from road vehicles and encouraged people to use cleaner fuels and vehicles.

However, you can also do you bit. Think before using your car and consider using alternatives, such as public transport, cycling or walking. You can also make a difference at home - by buying low solvent paints or being careful about when and what to light on bonfires.

More advice is available from Defra.

Air pollution from petrol stations to be cut by 85%

Defra have announced that damaging pollution from petrol fumes, which once leaked into the atmosphere whenever car tanks were topped up, will be captured and recycled as fuel under air quality rules which came into effect in October 2006.

Petrol fumes add to the formation of ‘summer smog', a combination of ground level ozone, which harms human health, vegetation, and buildings, and particulate matter – PM 10 - which is associated with premature mortality.

Now under the Petrol Vapour Recovery stage II controls (PVRII) every petrol station selling over 3.5 million litres of petrol a year has till 1 January 2010 to fit equipment to capture the fumes. This threshold has been set high enough to ensure that smaller service stations, particularly those in rural areas, will not face disproportionate costs which could affect their viability.

The technology will recover around 85% of the petrol fumes which would otherwise escape into the atmosphere - around 16,000 tonnes per year in total.

Ben Bradshaw, Minister for Air Quality, said:

“Summer smogs are a too familiar feature in some of our cities. They are tangible evidence of the implications for quality of life if we allow levels of pollutant emissions into the atmosphere to go unchecked.

“The legislation which comes into effect this month is part of a package of measures designed to reduce those levels and cut the risks to human health and the environment.

“The impact of the costs involved has been considered carefully. We want a common sense balance between the likely benefits for air quality and protecting the viability of businesses. That's why we are confining the measure to larger service stations. Many smaller rural service stations have a vital role in providing other services to communities, and we have set the threshold for fitting the equipment to ensure they are protected.”