Air Quality Index

Air Quality Index


  • The overall air quality in Delhi continued to remain in the ‘critical’ category on Monday morning, according to the System of Air Quality and Weather Forecasting and Research (SAFAR)-India.
  • Pollution levels in Delhi have remained in the ‘critical’ category for the past few days recording AQI in the ‘400’ range at several locations in and around Delhi.
  • According to data Data from the Central Pollution Control Board showed Delhi’s air quality index increased by over 200 points since October 27.

About AQI:

  • AQI is envisioned as the ‘One Number- One Colour-One Description’ for the common man to judge the air quality within his vicinity.
  • The formulation of the index was a continuation of the initiatives under Swachh Bharat Mission envisioned by the Hon’ble Prime Minister Shri NarendraModi.
  • While the earlier measuring index was limited to three indicators, the current measurement index had been made quite comprehensive by the addition of five additional parameters.
  • Under the current measurement of air quality, 8 parameters. The initiatives undertaken by the Ministry recently aimed at balancing environment and conservation and development.
  • Air pollution has been a matter of environmental and health concerns, particularly in urban areas.
  • Central Pollution Control Board along with State Pollution Control Boards has been operating National Air Monitoring Program (NAMP) covering 240 cities of the country.
  • In addition, continuous monitoring systems that provide data on near real-time basis are also installed in a few cities.
  • There are six AQI categories, namely Good, Satisfactory, Moderately polluted, Poor, Very Poor, and Severe.
  • The AQI will consider eight pollutants (PM10, PM5, NO2, SO2, CO, O3, NH3, and Pb) for which short-term (up to 24-hourly averaging period) National Ambient Air Quality Standards are prescribed.
  • Based on the measured ambient concentrations, corresponding standards and likely health impact, a sub-index is calculated for each of these pollutants.
  • The worst sub-index reflects overall AQI.
  • Associated likely health impacts for different AQI categories and pollutants have been also been suggested, 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:
AQI Category, Pollutants and Health Breakpoints
AQI Category (Range) PM10









8-hr (mg/m3)







Good (0-50) 0-50 0-30 0-40 0-50 0-1.0 0-40 0-200 0-0.5
Satisfactory (51-100) 51-100 31-60 41-80 51-100 1.1-2.0 41-80 201-400 0.5 –1.0
Moderately polluted


101-250 61-90 81-180 101-168 2.1- 10 81-380 401-800 1.1-2.0


251-350 91-120 181-280 169-208 10-17 381-800 801-1200 2.1-3.0
Very poor


351-430 121-250 281-400 209-748* 17-34 801-1600 1200-1800 3.1-3.5


430 + 250+ 400+ 748+* 34+ 1600+ 1800+ 3.5+


AQI Associated Health Impacts


Minimal Impact


May cause minor breathing discomfort to sensitive people.
Moderately polluted


May cause breathing discomfort to people with lung disease such as asthma, and discomfort to people with heart disease, children and older adults.


May cause breathing discomfort to people on prolonged exposure, and discomfort to people with heart disease
Very Poor


May cause respiratory illness to the people on prolonged exposure. Effect may be more pronounced in people with lung and heart diseases.


May cause respiratory impact even on healthy people, and serious health impacts on people with lung/heart disease. The health impacts may be experienced even during light physical activity.

Syllabus: Prelims