Major air pollutants - Overview

Air pollution is serious environmental and health issue in many countries across the globe. Air pollution is caused by different substances in the air known as air pollutants. The list of major air pollutants includes carbon dioxide, carbon monoxide, nitrogen and sulfur oxides, volatile organic compounds (VOCs) and particulates.

Carbon dioxide is greenhouse gas which is mostly emitted into air by fossil fuels burning. Carbon dioxide is not only major source of air pollution but also major source of climate change and ocean acidification.

Carbon monoxide is very poisonous gas that is mostly being created by the vehicular exhaust. Carbon monoxide poisoning is the most common type of fatal air poisoning in many countries. Exposure to carbon monoxide can also have severe adverse effects on the fetus of a pregnant woman.

Nitrogen dioxide (NO2) is usually the most talked about nitrogen oxide when mentioning air pollution. The most important sources of NO2 are internal combustion engines and thermal power plants. Long-term exposure to NO2 at concentrations above 40– 100 µg/m3 causes adverse effects on human health.

Sulfur dioxide (SO2) is another major air pollutant. Sulfur dioxide is not only produced by different industrial processes but also by volcanoes. Sulfur dioxide is also a precursor to particulates in the atmosphere.

Volatile organic compounds (VOCs) also belong to major air pollutants. Many VOCs are dangerous to both human health and environment. VOCs have a high vapor pressure and low water solubility. Concentrations of many VOCs are much higher indoors (up to ten times higher) than outdoors. The examples are paints and lacquers, paint strippers, cleaning supplies, pesticides, etc.

Particulates or particulate matter are tiny particles of solid or liquid suspended in a gas. The burning of fossil fuels in vehicles, power plants and industry are the major sources of particulates though some particulates originate naturally, for instance from volcanoes and dust storms. Overexposure to particulates in air can lead to heart disease and problems with lungs, including lung cancer.