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As Delhi-NCR and its environs grapple with worsening air pollution, the Air Quality Index (AQI) has gained prominence as a critical measure of air quality.
Understanding Air Quality Index (AQI)
- The AQI gauges the safety of the air you breathe in. The density of different air pollutants (PM2.5, PM10, nitrogen dioxide, ozone, etc.) is measured at numerous monitoring sites by organizations that report the AQI.
- The Central Pollution Control Board’s widely used National Air Quality Index (NAQI) is a 24- hour average.
- Micrograms per cubic meter are used as its unit.
- It’s possible that a given quantity of one pollutant won’t be as damaging as a similar quantity of another.
- As a result, the amount of each pollutant in the air is calibrated to a standard scale (for example, 0 to 500) that applies to all contaminants.
- Ultimately, the AQI for that particular time and place is determined by the pollutant with the lowest sub-index.
Air Pollutants covered:
- Nitrogen Dioxide (NO2),
- Sulphur Dioxide (SO2)
- Particulate Matter (size less than 10 µm) or PM 10
- Particulate Matter (size less than 2.5 µm) or PM2.5
- Ozone (O3)
- Carbon Monoxide (CO)
- Ammonia (NH3)
(Pollutants that most of us NEVER heard of-)
- Benzene (C6H6)
- Lead
- Benzo(a)Pyrene (BaP)
- Arsenic(As)
- Nickel (Ni)
Influence on Government Policy
- Action Plan for Graded Response (GRAP): When it comes to influencing government initiatives to reduce air pollution, the AQI is crucial. Emergency protocols, including Stage 3 of GRAP, are triggered when air quality in locations such as Delhi-NCR deteriorates.
- Quick Reaction: For example, swift action was taken in response to the recent drop in the AQI to the “severe” level. Entry for trucks into Delhi was restricted, and diesel four-wheelers that did not comply with BS-VI were forbidden. Regular operations for gasoline-powered vehicles continued.
About Graded Response Action Plan (GRAP)
- In 2014, a WHO research revealed Delhi to be the most polluted city in the world. This led to the creation of the GRAP.
- Following numerous expert discussions, the Supreme Court accepted GRAP in the 2016 case of M. C. Mehta v. Union of India.
- The Ministry of Environment, Forests, and Climate Change announced the first GRAP in January 2017. As of 2021, the Commission for Air Quality Management in NCR & Adjoining Areas (CAQM) is in charge of carrying out GRAP.
Implementation
- The Supreme Court-appointed EPCA will direct states to implement GRAP measures before 2021.
- The EPCA was dissolved in 2020, and the Commission for Air Quality Management (CAQM) took its place.
- The Indian Institute of Tropical Meteorology (IITM) and the India Meteorological Department (IMD) produce meteorological forecasts, which are the basis for the CAQM recommendations. The Air Quality Index (AQI) is also used.
