Describe the key points of the revised Global Air Quality Guidelines (AQGs) recently released by the World…

Question

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 ?

Ghissu Editorial · Accepted Answer

WHO's 2021 Air Quality Guidelines halve the annual PM2.5 value to 5 µg/m³, add new ozone, NO2 and CO metrics and four interim targets. India's NCAP must shift to PM2.5-based, airshed-wide and legally binding targets measured against a revision of India's 2009 NAAQS.

**Introduction**

The WHO's Global Air Quality Guidelines of September 2021, the first revision since 2005, recognise that air pollution harms health even at very low concentrations; India's 2009 standards lag far behind them.

**Key Points of the 2021 Guidelines**

1. **Six pollutants**: Health-based levels are set for PM2.5, PM10, ozone, NO2, SO2 and CO from systematic reviews of health evidence.
2. **Interim targets and good practice**: Four particulate interim targets allow stepwise progress, and good practice statements cover black carbon, ultrafine particles and dust storms.

**How They Differ from the 2005 Update**

SKETCH: comparison | WHO Guidelines 2005 vs 2021
a: 2005
b: 2021
- PM2.5 annual 10 :: PM2.5 annual 5
- PM2.5 daily 25 :: PM2.5 daily 15
- PM10 annual 20 :: PM10 annual 15
- NO2 annual 40 :: NO2 annual 10
- No CO daily value :: CO daily 4 mg

1. **Halved benchmark**: Annual PM2.5 fell from 10 to 5 µg/m³, so India's 40 µg/m³ standard is now eight times the guideline.
2. **New metrics**: Peak-season ozone, 24-hour NO2 and 24-hour CO values were added, while daily SO2 was relaxed from 20 to 40 µg/m³.

**Changes Needed in India's National Clean Air Programme**

1. **Health-based targets**: NCAP should track PM2.5, not only a percentage cut in PM10 across 131 cities, against a revised NAAQS climbing the WHO interim targets, as the Parliamentary Standing Committee (2025) urged.
2. **Airshed governance**: Regional bodies modelled on the Commission for Air Quality Management (2021) should manage the Indo-Gangetic airshed.
3. **Legal teeth and sources**: Statutory backing, source apportionment and enforcement of the 2015 power-plant emission norms would tie funds to outcomes, with rural monitoring extended.

**Conclusion**

A PM2.5-centred, airshed-based and legally binding NCAP that climbs the interim targets would turn the 2021 guidelines into health gains and move India towards SDG 3.9.

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 ?

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