Air Quality Index (AQI)

AQI measures how safe the air around you is for breathing. Organizations that report AQI measure the density of various pollutants in the air (such as PM2.5, PM10, nitrogen dioxide, ozone, etc) at different monitoring stations.
The widely-used National Air Quality Index (NAQI) given by the Central Pollution Control Board is a 24-hour average.
Its unit is micrograms per cubic meter.
A particular amount of one pollutant may not be as harmful as the same amount of another pollutant.
So, each pollutant’s quantity in the air is adjusted to a common scale (say, 0 to 500) that works for all pollutants.
Finally, the pollutant with the worst sub-index determines the AQI for that time and location.

What are NAAQ standards?

The mandate provided to the Central Pollution Control Board (CPCB) under the Air (Prevention and Control of Pollution) Act empowers it to set standards for the quality of air.
Hence the current National Ambient Air Quality Standards were notified in November 2009 by the CPCB.
Prior to this, India had set Air Quality standards in 1994, and this was later revised in 1998.
The 2009 standards further lowered the maximum permissible limits for pollutants and made the standards uniform across the nation.
Earlier, less stringent standards were prescribed for industrial zones as compared to residential areas.

Pollutants covered:

(Air Pollutants that most of us NEVER heard of)

System of Air Quality and Weather Forecasting and Research (SAFAR) Portal
Air Quality Index: AQI has been developed for eight pollutants viz. PM2.5, PM10, Ammonia, Lead, nitrogen oxides, sulphur dioxide, ozone, and carbon monoxide.
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