Describe the key points of the revised Global Air Quality Guidelines (AQGs) recently released by the World Health Organisation (WHO). How are these different from its last update in 2005? What changes in India’s National Clean Air Programme are required to achieve these revised standards ? (Answer in 150 words)

WHO’s 2021 AQGs tightened health-based recommendations because evidence shows harm from particulate matter and other pollutants at lower concentrations than previously recognised.

Key changes

• Annual PM2.5 guideline fell from 10 to 5 µg/m³ and PM10 from 20 to 15 µg/m³.
• Interim targets were retained to support staged improvement in highly polluted regions.
• Guidance was updated for NO₂, O₃, SO₂ and CO, with stronger emphasis on health protection and exposure reduction.

Implications for NCAP

• Shift from city averages to airshed-based management covering transport, industry, power, construction, waste and agriculture.
• Set legally enforceable, source-specific targets with continuous monitoring, emissions inventories and transparent health indicators.
• Prioritise clean fuels, public transport, dust control, stubble alternatives and independent compliance audits.

PM2.5; PM10; interim targets; airshed; emissions inventory; NCAP; health-based standards.