Despite significant reductions in emissions of many pollutants since the 1970’s, air pollution still causes significant harm to both public health and the natural environment. Air pollutants are largely the products of combustion and are emitted from various sources including power generation, industry, transport and agriculture.

Many of these sources are shared with greenhouse gas emissions. greenhouse gases are most active high in the atmosphere, whereas the most important factor for air quality is the concentration of pollutants closer to the ground. Nevertheless, air pollutants can travel long distances, chemically reacting in the atmosphere to produce other pollutants, leading to air pollution problems locally as well as a long way from the source (which is known as long-range transboundary air pollution).

Air pollutants are damaging to human health and adversely affect the natural environment in a number of ways.  Emissions of sulphur (SO₂), nitrogen (NO_X) and ammonia (NH₃) can be deposited to land and water causing either acidification, or nutrient enrichment (eutrophication).  This results in damage to biodiversity in both semi-natural environments and upland rivers and lakes. Ozone (O₃) on the other hand, can lead to direct damage to crops and vegetation, affecting ecosystem function and resulting in loss of crop yields.

Legislation

In response to the pressing need to tackle acid rain, an issue identified in the 1970s, the UK and other European countries, the US, Canada and Russia signed the United Nations Economic Commission for Europe’s (UNECE) Convention on Long-Range Transboundary Air Pollution (CLRTAP) in 1979.

Initially focused on reducing SO₂ emissions, the Convention was soon extended to cover other air pollutants under various protocols, with the aim of reducing transboundary air pollution.  In 1999, the Gothenburg Protocol was agreed, which set national emission limits (ceilings) for SO₂, NO_X, NH₃ and volatile organic compounds for countries to meet from 2010 onwards.  Similar ceilings have since been set in European law under the 2001 National Emission Ceilings Directive (2001/81/EC), which was subsequently made into UK law as the National Emission Ceilings Regulations 2002.

• Gothenburg Protocol
• National Emission Ceilings Directive (2001/81/EC)
• National Emission Ceilings Regulations 2002

European policies governing industrial emissions vehicle engine standards, and emissions from fuel and domestic sources as well as wider socio-economic policies and developments have contributed to reducing total UK air pollutant emissions. These actions were last summarised in the UK programme of measures that was reported to the European Commission in 2007.  Looking ahead, the requirements of the UK Climate Change Act will also bring about reductions in emissions of air pollutants. The links between air quality and climate change were set out in 2010 in the publication Air Pollution: Action in a changing climate.

• Vehicle engine standards
• Programme of measures (PDF120 KB)
• Air Pollution: Action in a changing climate

Emissions assessment

The UK maintains a National Atmospheric Emissions Inventory (NAEI) in which estimates of emissions to the atmosphere from UK pollution sources such as cars, trucks, power stations, industry and agricultural activities are compiled. The NAEI is continually improved and used to produce estimates of UK emissions on an annual basis.  This information is reported annually to the European Commission and UNECE as required in the National Emission Ceilings Directive and the protocols under the CLRTAP.

• NAEI website

The latest UK emissions data shows the UK to be compliant with its 2010 emission ceilings for all four of the major air pollutants. The UK is currently projected to remain compliant with its ceilings in 2010 and beyond.

• Latest UK emissions data (PDF 120 KB)

Review of national emission ceilings

Work is currently underway to review the Gothenburg Protocol with a view to encouraging more non-EU countries to sign up to the protocol whilst setting new emission ceilings for 2020 and updating the protocol’s technical requirements. Timing of review of the National Emissions Ceilings Directive is uncertain though the European Commission may include this in their planned review of the ambient air quality directive (2008/50/EC) (PDF 490 KB) in 2013.