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  • The National Air Quality Index (AQI) was launched in 2014 under the Swachh Bharat Abhiyan.
  • It is outlined as ‘One Number-One Colour-One Description’ for the common man to judge the air quality within his vicinity.
  • The index constitutes part of the government’s mission to introduce the culture of cleanliness.
  • The Indian Institute of Technology (ITT), Kanpur and the Expert Group recommended an AQI scheme in 2014.
  • The current measurement index is based on eight pollutants such as PM10, PM2.5, NO2, SO2, CO, O3, NH3, and Pb, for which short-term (up to twenty-four-hour averaging period) National Ambient Air Quality Standards (NAAQS) are prescribed.
  • Based on the measured ambient concentrations corresponding standards and likely health impact, sub-indexes are calculated for each of these pollutants.
  • The worst sub-index reflects the overall AQI.

AQI Category, Pollutants and Health Breakpoints

  • Associated likely health impacts for different AQI categories and pollutants are suggested under six AQI categories, namely, Good, Satisfactory, Moderately polluted, Poor, Very Poor and Severe with primary inputs from the medical expert members of the group.
  • The AQI values and corresponding ambient concentrations (health breakpoints) as well as associated likely health impacts for the identified eight pollutants are as follows.
  • The Central Pollution Control Board along with the State Pollution Control Boards has been operating National Air Monitoring Programme (NAMP) covering 240 cities of the country having more than 342 monitoring stations.
  • In addition, continuous monitoring systems that provide data on near real-time basis are also installed in few cities.
  • The monitoring systems provide information on air quality in the public domain in simple linguistic terms that is easily understood by a common person.

List of Eight Pollutants under National AQI:

  1. Carbon monoxide (CO)
  2. Nitrogen dioxide (NO2)
  3. Sulphur dioxide (SO2)
  4. Particulate matter (PM) of less than 2.5 microns size (PM 5)
  5. PM of less than 10 microns size (PM10)
  6. Ozone (03)
  7. Lead (Pb)
  8. Ammonia (NH3).

Micron is a unit of length equal to one millionth of a metre.


Environment & Biodiversity

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