Air Quality Index

Air pollution is nothing that we are not aware of; by now, we all know the source, the problems or the health risks. But did you know that methods tell us the air quality we are breathing? Air quality index- a number that tells you which pollutant is present in the air, in what amount, how sensitive it is for your health, etc. If you are preparing for the UPSC Exam, you must thoroughly understand AQI.

What is air quality index?

The Air Quality Index is acquired by measuring emissions of eight major pollutants present in the air: Particulate matter (PM2.5 and PM10), Ozone (O3), Carbon Monoxide (CO), Nitrogen Dioxide (NO2), Sulphur Dioxide (SO2), Lead (Pb) and Ammonia (NH3) emissions. Readings are noted every hour. Each country has their air quality indexes based on its air quality standards.

Air Quality Index India

The government agencies are responsible for communicating to the public about the health hazards and how to keep a check on them. Under the Swachh Bharat Abhiyan, the National Air Quality Index was launched in September 2014 in New Delhi to measure India’s air quality index.

The Central Pollution Control Board (CPCB) has formed an expert group of medical professionals, air quality experts, academia, advocacy groups, and SPCBs. Also, a technical study was awarded to IIT Kanpur. In 2014, the IIT Kanpur and the expert group recommended an AQI scheme for India.

Six cities of India- New Delhi, Kolkata, Mumbai, Pune, and Ahmedabad have a continuous monitoring system that records data in real-time.

Instrument to Measure Air Quality

Few instruments that are used for measuring air quality are:

  1. PCE-RCM 05
  2. PCE-RCM 8
  3. PCE-HFX 100

Calculation of AQI

The computation of the AQI is based on the average air pollutant concentration over a specified period, which is obtained from an air monitor or model.

The AQI increases because of an increase in the emission of air pollutants; for example, during heavy traffic or forest fire, a high value of AQI is observed. In addition, due to anticyclone or temperature inversion, Stagnant air leads to high concentrations of pollutants in the air. This results in chemical reactions between air pollutants and hazy conditions, thus increasing the AQI.

Particulate Matter or PM: A substantial pollutant

PM 2.5 and PM 10 is the most common method of measuring air quality. It measures the particles in micrograms per cubic metre. As a UPSC 2023 aspirant, you must know about Particulate Matter or PM. It is a mixture of solid particles and liquid droplets present in the air. While some particles such as dust, smoke and soot are visible through naked eyes, numerous others are visible only through an electron microscope. Pollutants emitted by power plants, industries, automobiles, etc., form complex chemical reactions in the air, thus producing particulate matter.

Categories of Air Quality Index

The National Air Quality Index has set up six AQI categories: Good, Satisfactory, Moderately polluted, Poor, Very Poor, and Severe. Each category specifies health impacts associated with it as mentioned below given table:

AQI Category Health Impacts
0-50 Good/ Safe Minimal Impact
51-100 Satisfactory Sensitive people might experience minor breathing discomfort
101-200 Moderately polluted Lung disease patients may have discomfort in breathing, and heart disease, children and older adults might experience discomfort
201-300 Poor Breathing discomfort on prolonged exposure, and discomfort to heart disease patients
301-400 Very poor Prolonged exposure might lead to respiratory illness. Severely affects people with lung and heart diseases.
401-500 Severe While healthy people may experience respiratory problems, lung or heart disease patients can have severe health impacts. Even during light physical activity, people may experience health impacts.

Under the current affairs quiz, you will come across questions related to the air quality index of India and measures taken to manage the value to a safer level or how to protect our health from the adverse effects of air pollution.

Frequently Asked Questions on Air Quality Index


What is PM 2.5 and PM 10?

PM 2.5 refers to the concentration of microscopic particles less than 2.5 microns in diameter, and PM 10 refers to the concentration of particles less than 10 microns in diameter.


When was the National Air Quality Index India launched?

The National Air Quality Quality (AQI) India was launched on 17 September 2014 in New Delhi under the Swachh Bharat Abhiyan by Environment Minister Shri PrakashJavadekar.


Which city in India has the worst air quality?

New Delhi, the capital of India, has the worst air quality, according to the National Air Quality Index, where the main components of air pollution are the PM 2.5 and PM 10 particles.


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