Major UK Air Pollution Emissions from Power Stations & Industry
Introduction
Industries contribute significantly to the air pollution problems in the UK. During the Industrial Revolution industries were often located in urban areas. Following the Clean Air Acts and with the decline in heavy industry, few large industries and power stations are located in towns and cities today. Many large industries are now located in the more rural areas of the UK. However, most urban areas have some smaller industries and possibly a power station. The larger industrial sources, even though located out of town, also have an impact on urban air quality.
Industrial Smoke Pollution
Smoke pollution can be defined as particulate material less than 15mm in diameter, which arises from the incomplete combustion of fuel. Estimates for emission of particulates which are 10 m in diameter or less (PM10) in the UK for 2001 identify that power stations account for 10% of UK emissions and other industries for 21%. The significant sources of smoke pollution are therefore not industries, but rather vehicles (24%), other sources such as construction, agriculture (24%) and domestic and commercial sources (21%).
In the past, urban air pollution was dominated by thick black smoke, which was emitted by industries and power plants burning coal. Levels of smoke in cities and towns during the wintertime in particular were at much higher concentrations than those measured today. In the early 1960s, winter smoke concentrations in Manchester averaged at more than 250mgm-3. Today the typical urban annual mean for smoke is 10 - 40mgm-3. The amount has decreased dramatically due to technical industrial air pollution control, the decline in the use of coal for domestic purposes and the general shift of power stations and industries from town and city centres to more rural locations.
Sulphur Dioxide Pollution
Industries are the major source of UK sulphur dioxide pollution. Power stations and all other types of industry account for 90% of all UK SO2 pollution. Most industries and power stations are now located in rural areas, but urban areas often lie in the prevailing wind path of these industries.
Small industries located within urban areas may greatly affect local SO2 levels as their emissions may become trapped by temperature inversions in the urban environment.
Sulphur dioxide pollution is one of the main pollutants that cause acid rain, when it combines with water in the atmosphere to form sulphuric acid. Industry is the main source of SO2 in the UK and therefore also the main contributors to rainfall acidity. Acid rain affects urban areas by causing faster erosion of certain building materials and it can causes damage to urban vegetation.
Industrial Oxides of Nitrogen Pollution
Power stations contribute significantly to the total emissions of nitrogen oxides in the UK. In 2001, 23% of NOx came from this source and a further 13% from other industries, iron and steel and refineries. The major source of NOx pollution in the UK is road transport (50%).
Whilst the majority of NOx emissions arise from road transport, the contribution of industrial NOx pollution is still important. Nitrogen oxides are also converted into nitric acid when combined with water in the atmosphere, hence, like SO2, contributing to acid rain.
Other Air Pollutants
Industries do not emit large quantities of the other urban air pollutants. The UK contribution of power stations and industrial sources in 2001 for carbon monoxide was 5% and for volatile organic compounds only 1%.
Conclusion
Power generation and industry are the main sources of sulphur dioxide emissions, the precursor for sulphuric acid in acid rain, in the UK. Such emissions, however, have been falling steadily since 1990. For other major air pollutants, including oxides of nitrogen, particles, VOCs and carbon monoxide, transport accounts for a much larger proportion of UK emissions than power generation and industry.