Exposure to air pollutants may adversely affect human health. For instance, ambient air pollution increases the risk of diseases in the heart and lung and can reduce life expectancy. The pollutants that are most harmful to health are inhalable particulate matter, ground-level ozone, nitrogen dioxide and certain hydrocarbons.
Air pollution also causes corrosion, speeding the breakdown of materials such as metals, plastics and limestone. This can, for example, result in damage to buildings and objects of cultural heritage. Soiling by soot and particulate matter may also be of importance. In addition, exposure to ground-level ozone causes damage to forest trees and farm crops, resulting in stunted growth and lower yields.
Damage to health, vegetation and materials by air pollutants represents a large cost to society in terms, for instance, of health care, reduced harvests and repair to valuable objects.
Local emissions, from industrial plants, vehicles, wood-fired domestic heating and other sources, affect the air in the local surroundings as well as on the regional and global scales. Several pollutants such as particulate matter, nitrogen oxides, sulfur dioxide and ground-level ozone, can be transported long distances across national borders and may cause harm far away from there sources.
What are the challenges?
A major source of air pollution, especially in urban areas, is road traffic. Vehicle exhausts contain particulate matter, nitrogen dioxide and organic compounds, and promote the formation of ground-level ozone. Traffic also causes emissions of abrasion particles, produced from road surfaces by the use of studded tyres. Positive trends include increasingly efficient engines, new fuels that are more environmentally-friendly and decreasing use of studded-tyres, but these developments are partly offset by a constant growth in traffic. In many towns, air quality problems can also arise from emissions of particles and organic compounds from the burning of wood.
To reduce emissions of pollutants that are transported over long distances by winds, international cooperation is ongoing within both the EU and the UN.