Air pollution is a complex mix of particles and gases of both natural and human origin. Particulate matter (PM) and nitrogen dioxide (NO2) are both major components of urban air pollution.
Nitrogen dioxide (NO) and nitric oxide (NO) are oxides of nitrogen collectively referred to as nitrogen oxides (NOx). All combustion processes produce NOx emissions, largely in the form of nitric oxide, which is converted to nitrogen dioxide, mainly as a result of reaction with ozone in the atmosphere. 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 (1).
PM is a generic term used to describe a complex mixture of solid and liquid particles of varying size, shape, and composition. 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.
Air pollution can affect everyone, and air in all areas of the UK contains some proportion of man-made air pollutants. Generally if you are young and in a good state of health, moderate air pollution levels are unlikely to have any serious short term effects. However at very high levels, air pollution can have various different health effects, which come about at every stage of life. The health effects of air pollution are complex, and range in severity of impact. In some cases, damage can be gradual and may not become apparent for many years (1).
There is currently concern about PM2.5 because "there is no evidence of a safe level of exposure to or a threshold below which no adverse health effects occur" (1). The technical evidence shows that smaller particles are more closely associated with adverse health effects. Although there is no specific air quality objective in the National Strategy, the Government has set a target reduction value of 15% in the concentration of PM2.5 at urban sites to be achieved by the end of the period 2010 – 2020.
The annual health cost to society of the impacts of particulate matter alone in the UK is estimated to be around £16 billion (1).
Our air quality action plan steering group, together with NHS Hampshire, has published a leaflet (974 KB) on the subject of poor local air quality. It lets you know how you can help reduce local air pollution by thinking about more sustainable forms of transport such as walking, cycling, taking public transport or car sharing. If you would like a copy please contact firstname.lastname@example.org.
Further information on air quality can be found at the following websites: