Air Pollution



An air pollutant is known as a substance in the air that can cause harm to humans and the environment. Pollutants can be in the form of solid particles, liquid droplets, or gases. In addition, they may be natural or man-made.
Pollutants can be classified as either primary or secondary. Usually, primary pollutants are substances directly emitted from a process, such as ash from a volcanic eruption, the carbon monoxide gas from a motor vehicle exhaust or sulfur dioxide released from factories.
Secondary pollutants are not emitted directly. Rather, they form in the air when primary pollutants react or interact. An important example of a secondary pollutant is ground level ozone - one of the many secondary pollutants that make up photochemical smog.


Sources of air pollution refer to the various locations, activities or factors which are responsible for the releasing of pollutants in the atmosphere. These sources can be classified into two major categories which are:
Anthropogenic sources (human activity) mostly related to burning different kinds of fuel
• "Stationary Sources" as smoke stacks of power plants, manufacturing facilities, municipal waste incinerators.
• "Mobile Sources" as motor vehicles, aircraft etc.
• Marine vessels, such as container ships or cruise ships, and related port air pollution.
• Burning wood, fireplaces, stoves, furnaces and incinerators .
• Oil refining, and industrial activity in general.
• Chemicals, dust and controlled burn practices in agriculture and forestry management, (see Dust Bowl).
• Fumes from paint, hair spray, varnish, aerosol sprays and other solvents.
• Waste deposition in landfills, which generate methane.
• Military, such as nuclear weapons, toxic gases, germ warfare and rocketry.
Natural sources
• Dust from natural sources, usually large areas of land with little or no vegetation.
• Methane, emitted by the digestion of food by animals, for example...