Air Quality Index (AQI)


    In News

    • Recently, the AQI in NCR dipped to the ‘severe’ category.

    About Air Quality Index (AQI)


    • Background
      • It was launched by the central government in 2014 as part of the Swachh Bharat campaign
      • IIT Kanpur and the Expert Group recommended an AQI scheme.
    • Meaning
      • AQI is a number, which is a measure of air quality
      • The higher the AQI, the worse the air.
    • Pollutants
      • The pollutants measured include PM 10, PM 2.5, Nitrogen Dioxide, Ozone, Carbon, etc. 
    • There are six categories of AQI:
      • Good (0-50)
      • Satisfactory (50-100)
      • Moderately polluted (100-200)
      • Poor (200-300)
      • Very Poor (300-400)
      • Severe (400-500)
    • The colour-coded AQI index was launched in India in 2014, and it helps the public and the government understand the condition of the air and what subsequent measures are to be taken to combat the situation, based on its severity.

    What is GRAP?


    • It was first implemented in 2017. 
    • The GRAP is a set of anti-air pollution measures followed in the capital and its vicinity according to the severity of the situation.
    • It classifies the air quality in the Delhi-NCR under four different stages: 
      • Stage 1 – “poor” (AQI 201-300)
      • Stage 2 – “very poor” (AQI 301-400)
      • Stage 3 – “severe” (AQI 401-450) 
      • Stage 4 – “severe plus” (AQI above 450).

    Impact of PM 2.5

    • It is an atmospheric particulate matter of diameter smaller than 2.5 micrometres (or around 3 percent of the diameter of a human hair).
    • It causes respiratory problems and reduces visibility.
    • The particles can only be detected with the help of an electron microscope because they are so small.
    • It can easily bypass the nose and throat and can easily enter the circulatory system.
    • The particles can also lead to chronic diseases such as asthma, heart attack, bronchitis and other respiratory problems. 

    Source: IE