Through our everyday activities, we have been gradually polluting the atmosphere, putting at risk our health and the health of our environment. The emission of pollutants from motor vehicles, industrial plants and other commercial and domestic activities, such as domestic wood burning, can increase concentrations of pollutant gases and particles in the atmosphere to levels that have harmful effects on humans and other organisms. There are also sources of pollution that we indirectly affect, such as wind-blown dust. Air pollution creates global problems, such as ozone layer depletion and global warming, that require national and global action. These pages only look at urban air pollution.
Some pollutants can interact to form secondary pollutants.
Air pollution can cause health problems. For example, smog can aggravate existing respiratory ailments such as asthma and bronchitis, or increase the risk of respiratory problems, particularly on smog days. Elevated lead levels can affect the central nervous system, and may impair intellectual development in children. Standards in the Ambient Air Quality NEPM are used to determine whether the air is of a quality that ensures the protection of human health and well being. The AAQ NEPM also specifies how the pollutants should be measured in conjuction with the standards.