A composite, standardized environmental metric that converts complex, individual ambient concentrations of criteria air pollutants into a single numerical score, risk category, and colour code to communicate air pollution levels and associated health risks to the public.

Background:

• Launched on September 17, 2014, in New Delhi under the Swachh Bharat Abhiyan initiative by the Ministry of Environment, Forest and Climate Change (MoEFCC).
• Formulated by the Central Pollution Control Board (CPCB) in technical collaboration with IIT Kanpur and an expert committee of environmental health scientists.

AQI Categories and Health Breakpoints

• India’s official AQI framework classifies air quality across six standardized colour-coded bands:

Key Features of the AQI:

• Eight Criteria Pollutants: Monitors eight major air pollutants: PM₁₀, PM₂.₅, NO₂, SO₂, CO, O₃, NH₃ and Pb, assessing ambient air quality and associated health risks.
• Worst-Pollutant Principle: The highest pollutant sub-index determines the overall AQI, rather than an average, preventing severe pollution from individual pollutants from being masked.
• Minimum Data Requirement: AQI calculation requires data for at least three pollutants, including at least one particulate pollutant (PM₂.₅ or PM₁₀).
• Maximum AQI Limit: India’s official AQI scale is capped at 500, even when pollutant concentrations exceed severe thresholds, unlike some international reporting scales.