Air Quality Index

About Air Quality Index

AQI is a number, which is a measure of air quality. The higher the AQI, the worse the air.
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.

There are six categories of AQI, namely ‘Good’ (0-50), ‘Satisfactory’ (51-100), ‘Moderately polluted’ (101-200), ‘Poor’ (201-300), ‘Very Poor’ (301-400), and ‘Severe’ (401-500).
The pollutants measured include PM 10, PM 2.5, Nitrogen Dioxide, Ozone, Carbon, etc.

What is the impact of these pollutants?

Among the more harmful pollutants are those of a smaller size, such as particulate matter (PM) 2.5, which is an atmospheric particulate matter of diameter smaller than 2.5 micrometres.
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.
Due to their size, the PM 2.5 particles 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.

Why in News?

As per Air Quality Index (AQI) data of the Central Pollution Control Board (CPCB), Delhi has witnessed maximum number of days with ‘Good to Moderate’ Air Quality during the first four months’ period of 2023 (i.e. January to April), as compared to the corresponding period of last 07 years since 2016 (barring the periods of very low anthropogenic, industrial and commercial activities during the Covid-19 lockdown year 2020).
A comparative chart for days with ‘Good to Moderate’ AQI witnessed for the first four months’ period during the 08 years (2016-2023) is depicted below:

In terms of daily average PM2.5 concentration levels in Delhi, 2023 has been the year with lowest levels of daily average PM2.5 concentration, as compared to the corresponding period for last 07 years i.e. from 2016 (barring 2020 – the year of Covid lockdown).
Moreover, 2023 has also been the year with lowest levels of daily average PM10 concentration in Delhi, as compared to the corresponding period for last 07 years i.e. from 2016 (barring 2020 – the year of Covid lockdown).
Delhi has also reported its lowest Average AQI in 2023 as compared to the corresponding period for last 07 years i.e. from 2016 (barring 2020 – the year of Covid lockdown).
A comparative chart depicting the Average AQI for the first four months’ period (January to April) during the 08 years (2016-2023) is given below:

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