What is air quality Index

What is Air Quality Index

According to world heath organization 90% of Earth population inhale polluted air. Every country, including India, is facing this problem.
There are some cities of India in top 12 most polluted cities of the world like Delhi, Faridabad and Kanpur, where the level of pollution is very high and it's average value is more than 300. But how people find the level of pollution of a particular place?

To indicate the level of pollution we use AQI (Air Quality Index). Air quality Index is a numerical scale from which we get day to day air pollution level report on human health and environment. We measure Air Quality Index in between 0 to 500 unit scale. According to it's value we identify the air pollution level. If the value of it is high then the pollution level is high.

Identification of air pollution

If the level of air quality Index is 50 unit or less then it is said to be good quality Index.

If the value air quality Index  is between 50 and 100 units the level of pollution is moderate.

If the value of air quality Index is in between 100 and 150 units, then the air quality is said to be unhealthy.

The value of air quality Index in between 150 to 200 then the air is said to be very unhealthy.

If the value of air quality Index is between 200 to 250 then it is not suitable for humans to live in such polluted air.

If the value of air is more than 300 then it is hazardous for humans. It can be very much harmful for humans.

CPCB ( central pollution control board) has set a limit of quality.

Components of Air Quality Index

Particulate matter (PM)
Nitrogen oxide
Sulfur dioxide
Carbon monoxide

Components of Air Quality Index

Particulate matter (PM)
Nitrogen oxide
Sulfur dioxide
Carbon monoxide

These are the components which causes the value of Air quality Index to rise up. The most dangerous and harmful pollutant is particulate matter.
Particulate matter is the fine particles which pollutes air.  There are two types of particulate matter PM10 and PM2.5 .  PM10 are 10 micron diameter particles and PM2.5 is are 2.5 micron diameter particles. These particles can enter into the body by enhaling polluted air which can be a cause of asthama. These pollutants comes through both indoor and outdoor activities, Outdoor activities which produce PM10 and PM2.5 are vehicle smokes, smoke from industries, forest fire, volcano eruption and the main source of this pollutants is thermal power plants, to generate electricity people are burning coal continuously which produce a huge amount of this pollutants. Indoor activities which produce these pollutants are smoking, traditional cooking system and use of fossil fuels. These particles are present in the environment in both water and air.

Some PM10 particles get into the surface through rain drop but some particles of PM2.5 are still present in the atmosphere. So after raining we can see the air pollution has decreased and visibility increases.

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References:- wikipedia and quora