Air Pollution

Posted and illustrated  by: Margie Babon

 air pollution

 Air pollution is the release into Earth’s atmosphere of substances that can cause harm or discomfort to living things. Pollutants are most often gases, but they can also take the form of fine solid particles (as in smoke) or tiny liquid droplets. Some air pollution results from natural phenomena such as volcanic eruptions, but more important factor is human activity, including coal-burning power stations, vehicle exhausts and agricultural burning.

The seven air pollutants highlighted here are among the most important. Other includes ammonia, volatile organic compounds (VOCs), and some toxic metals. A particularly noxious form of air pollution, photochemical smog, tends to develop in places that have both a dry, sunny climate and a huge number of automobiles for example, Mexico City and Los Angeles.

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Ozone is an uncommon form of oxygen that has three atoms in each molecule. Ozone in the stratosphere protects life on Earth by absorbing excess solar radiation. Near the ground, it can harm the lungs. In the lower atmosphere, ozone contributes to global warming.


Carbon Dioxide (CO2)

A colorless gas, carbon dioxide is considered a pollutant because it is a “greenhouse gas” and the main contributor to global warming. The main sources of carbon dioxide in the atmosphere include natural events such as volcanoes and human activity—notably the burning of fossil fuels such as gasoline and coal.



Particulates are fine particles floating in the air. Some occur naturally, originating from forest fires, volcanic eruptions, or dust storms. Other result from burning fossil fuels in power plants or are produced in car exhausts. A high level or particulate increases the risk of lung disease. Some of the most pollutant cities have concentrations up to six times higher than healthy levels.


Carbon Monoxide

A colorless, colorless gas, carbon monoxide is produced by wood fires and is also present in cigarette smoke. The gas is toxic because it reduces the blood’s ability to carry oxygen around the body. Most carbon monoxide in city air comes from car fumes. In some cities that gas is present ata level of 150 parts per million (good air quality requires a level below 10ppm).


Nitrogen Dioxide (NO2)

This acrid gas produced by power stations is present in vehicle exhausts and plays a part in ozone formation of acid rain. Good air quality specifies a concentration below 30 parts per billion. Higher levels can damage the lungs.


Sulfur Dioxide (SO2)

A colorless, pungent gas produced by many industrial processes, sulfur dioxide irritates the lungs. In the air, it combines with tiny water droplets to form into dilute sulfuric acid, a major component of “acid rain,” which is harmful to plants and aquatic animals. In some cities, levels reach over 200 parts per billion, whereas for good air quality, alevel below 50 ppb is required.



Once a major pollutant in car exhaust, fumes, emissions of lead from this source have dropped by 98 percent since leaded gasoline was phased out. Itis still emitted by some metal processing and battery processing plants. If breathed in, lead can damage many parts of the body and slows mental development in children. A concentration below 0.2 parts per billion is desirable.



Important Facts:

  • The main sources of human-caused air pollution are power stations, vehicle emissions, and agricultural burning.
  • The World Health Organization estimates that about two million premature deaths are caused by air pollution in cities across the world.
  • Polluted air is particularly damaging to those who have lung and heart disease.
  • The removal of lead from gasoline in the 1990s has been a notable success in the fight against air pollution.



Source: Wikipedia, Bite-size science


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