Air Quality Management

What do WRS do?

Worcestershire Regulatory Services undertake monitoring, assessment and reporting of air quality in the county on behalf of the six district authorities. Additionally, we provide technical guidance to our district authorities and Air Quality Partners to inform local strategies and policies and to make informed decisions, for example for planning applications.

We collaborate with neighbouring authority air quality experts and other groups such as sustainability and public health colleagues, and local academia to improve air quality across the West Midlands. We also raise awareness of air pollution and encourage behavioural change to protect human health and the environment through working with local schools and communities, and provision of information on these webpages.

Click the links below to find out further information on the work we do, about air pollutants and health, advice on how to protect yourself, your family and environment and to access interactive maps of current air quality in Worcestershire.

Common atmospheric pollutants

NO2 is a gas that is produced along with nitric oxide (NO) by combustion processes. Together they are often referred to as oxides of nitrogen (NOx).

The Department for Environment, Food & Rural Affairs (Defra) estimates that 80% of NOx emissions in areas where the UK is exceeding NO2 limits are due to transport, with the largest source being emissions from diesel light duty vehicles (cars and vans). Other sources include power generation, industrial processes, and domestic heating.

The Committee on the Medical Effects of Air Pollutants (COMEAP) has established that short-term exposure to NO2, particularly at high concentrations, is a respiratory irritant that can cause inflammation of the airways leading to - for example - cough, production of mucus and shortness of breath. Studies have shown associations of NO2 in outdoor air with reduced lung development, and respiratory infections in early childhood and effects on lung function in adulthood.

Epidemiological studies have also shown associations of outdoor NO2 with adverse effects on health, including reduced life expectancy. It has been unclear whether these effects are caused by NO2 itself, or by other pollutants emitted at the same time by sources such as road traffic.


PM is a generic term used to describe a complex mixture of solid and liquid particles of varying size, shape, and composition. Some particles are emitted directly (primary PM); others are formed in the atmosphere through complex chemical reactions (secondary PM). The composition of PM varies greatly and depends on many factors, such as geographical location, emission sources and weather.

The main sources of man-made PM are the combustion of fuels (by vehicles, industry and domestic properties) and other physical processes such as tyre and brake wear. Natural sources include wind-blown soil and dust, sea spray particles, and fires involving burning vegetation.

PM is often classified according to by aerodynamic size and referred to as:

  • coarse particles (PM10; particles that are less than 10 microns (µm) in diameter)
  • fine particles (PM2.5; particles that are less than 2.5 µm in diameter)
  • ultrafine particles (PM0.1; particles that are less than 0.1 µm in diameter)

The size of particles and the duration of exposure are key determinants of potential adverse health effects. Particles larger than 10 µm are mainly deposited in the nose or throat, whereas particles smaller than 10 µm pose the greatest risk because they can be drawn deeper into the lung. The strongest evidence for effects on health is associated with fine particles (PM2.5).

There is an extensive body of evidence that long-term exposure to PM increases mortality and morbidity from cardiovascular and respiratory diseases. Outdoor air pollution, particularly PM, has also been classified by the International Agency for Research on Cancer (IARC) as carcinogenic to humans (a Group 1 carcinogen) and causing lung cancer. There is some experimental evidence, however, that ultrafine particles may also pass through the lungs into the bloodstream.


SO2 is produced when sulphur-containing fuels, such as coal, are burned. It is an invisible gas with a sharp smell and can dissolve in water. Chemical reactions of SO2 can also produce sulphates, which remain in the air as secondary particles, contributing to the PM mix.

SO2 has an irritant effect on the lining of the nose, throat and airways, and the effects are often felt very quickly. Due to the increased use of gas and electricity, coal-burning is now relatively uncommon, and levels of SO2 have steadily declined over the last 50 years. Most SO2 in the UK now comes from industrial sources, such as coal and oil-burning power stations, as well as domestic sources such as boilers and stoves.


NH3 is a gas released into the atmosphere from natural and man-made sources. Once emitted into the atmosphere, the subsequent deposition of NH3 can be a major source of pollution, causing nitrogen (N) enrichment (eutrophication) and acidification of soil and water sources. Atmospheric NH3 also reacts with acid gases, such as sulphuric and nitric acid, to form secondary PM2.5.

The main health impacts of NH3 arise through its role in secondary PM2.5 formation and health effects associated with exposure to PM, as described above. Thus, NH3 not only plays a role in acidification and eutrophication but also contributes to the overall PM burden. Agricultural emissions of NH3 have been reported to be key contributor to some short-term episodes of high PM pollution in recent years.


CO is a colourless, odourless and tasteless gas, produced when fuels such as gas, oil, coal and wood burn without enough oxygen. These are sources of fuel used in many household appliances, including boilers, central heating systems, gas fires, water heaters, cookers and open fires. Burning charcoal, running cars and the smoke from cigarettes also produce CO gas.

Exposure to high indoor levels can be fatal, while exposure to lower levels can result in symptoms that resemble flu, viral infections or food poisoning.


Ozone is a very reactive chemical, which is potentially toxic to both plants and animals. In the stratosphere, ozone helps to protect the earth from the harmful effects of ultra-violet rays from the sun. However at ground level it is a pollutant.

Unlike the other pollutants mentioned above, ozone is not emitted directly. Rather, it is formed as a result of a complex series of reactions involving hydrocarbons, sunlight and nitrogen dioxide (NO2).

The involvement of sunlight in this process means that ozone levels tend to be highest in summer. The reactions take time to generate ozone and the highest concentrations are frequently experienced many miles away from the source of the pollution, perhaps in rural areas. In fact, a significant proportion of ozone incidents experienced in the UK are due to pollution imported from abroad.

The problem of ozone pollution can therefore only be adequately dealt with as a result of international agreements