Air Pollution

Sources

Because air pollutants are classified by how they are formed, it is important to know which ones are directly released into the atmosphere and which are subsequently formed by chemical reactions that take place in the atmosphere. Air pollution is also characterized by geographic source. The geographic sources of air pollution are divided into three main categories: point source, line source, and regional source. Point sources refer to any air pollutants that result from a single “ejection” point. For example, a volcanic eruption or a manufacturing plant would be a point source. A line source of pollutants occurs when a number of point sources are connected. The prime example of a line source is a long traffic jam extended over a stretch of highway. A regional source is comprised of any number of point and line sources that pollute a large area. Some examples of regional sources include fuel combustion, industrial process losses, and waste disposal.

Generally, people associate air pollution with human activity, though this is not always the case. Anthropogenic sources are those caused by human activities, such as the burning of fuel and combustion within factories and power plants. Motor vehicles and large marine vessels running mainly on coal or fuel power generate harmful fuel emissions into the air. Stoves or furnaces that run on wood, coal, natural gas, oil, or fuel also release toxic chemicals into the air. Landfills, with their tons of waste, can produce methane gas and release it into the environment. The military's use of nuclear weapons, toxic gases, and germ warfare also discharges harmful emissions into the atmosphere. Even household products can have extremely harmful effects: The fumes from paint, varnish, aerosol sprays, and other solvents can cast harmful vapors into the air.

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