POLLUTION-CHINA.COM

The air we are breathing is essential for our life as it supplies us with oxygen. Clear air is a balance of nitrogen (78%) and oxygen (21%), water vapor as well as small amounts of inert gases such as neon, carbon dioxide or helium.

Unfortunately, pollutants which can be released into the air by human activities, alter this mixture and pose health risks to everyone who breathes air and can therefore cause problems to humans, animals and also plants. As a recognized threat to human health, air pollution is responsible for a large number of deaths and both acute and chronic respiratory diseases, which enforces the set up of worldwide air quality standards.

Air pollution is composed of several main types of pollutants such as particulate matter (PM10 or PM 2.5), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), ozone (O₃),  volatile organic compounds (VOCs), carbon monoxide (CO)...

In developping countries the major air pollution problem is still high levels of smoke and SO2 arising from the combustion of fossil fuels. In developped countries, the main threat to the air is posed by the traffic as vehicles emit a wide variety of pollutants ranging from CO, oxides of nitrogen (NO_x), VOCs to particulates (PM10).

The major pollutants

Substances that are not naturally found in the air or found in different locations or at greater concentrations as usual are called “pollutants”. In classifying pollutants you can distinguish two classes: primary and secondary pollutants.

Primary pollutants are directly produced by a process such as carbon monoxide (CO) gas from a motor vehicle exhaust.

Secondary pollutants are not emitted, but are formed when primary pollutants react or interact. Ground level ozone which is one cause for the formation of smog belongs to this group of secondary pollutants.

Some pollutants may even be both primary and secondary; they are emitted but can also be formed by interaction of other pollutants.

The major pollutants:

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