UPSC Mains 2021 GS Paper 3 Q7: model answer
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?
What the question wants
Describe the key points of the WHO's 2021 Air Quality Guidelines, how they differ from 2005, and what NCAP changes are needed to meet them.
How to structure it
New AQGs, differences, NCAP changes.
- Key points
- Differences from 2005
- NCAP changes
How to think it through
Sept 2021: first update since 2005; based on evidence that harm occurs at lower levels. PM2.5 annual 10→5 µg/m³, 24h 25→15; PM10 annual 20→15, 24h 50→45; NO2 annual 40→10, new 24h 25; ozone new peak-season 60; CO new 24h 4 mg/m³; SO2 24h 20→40. Interim targets for countries. India NAAQS 2009: PM2.5 annual 40. NCAP changes: PM2.5 focus, revise NAAQS, binding targets, airshed approach, health-based, monitoring expansion.
Model answer
In September 2021, the World Health Organization revised its Air Quality Guidelines for the first time since 2005. The message was blunt: air pollution harms health at much lower levels than once thought.
Key points
- Guideline values for six pollutants: PM2.5, PM10, ozone, nitrogen dioxide, sulphur dioxide and carbon monoxide.
- Interim targets to help polluted countries improve step by step.
How they differ from 2005
- PM2.5 annual: halved from 10 to 5 µg/m³; 24-hour from 25 to 15.
- PM10 annual: from 20 to 15; 24-hour from 50 to 45.
- Nitrogen dioxide annual: cut sharply from 40 to 10.
- New limits for peak-season ozone and 24-hour carbon monoxide.
Changes needed in NCAP
- India's PM2.5 standard is 40 µg/m³ a year, eight times the WHO value; revise the NAAQS in stages using the interim targets.
- Shift NCAP's focus from PM10 to PM2.5.
- Make targets binding, with an airshed approach across states.
- Expand monitoring to rural areas.
The WHO has moved the goalposts closer to health; India must move its targets towards them.
Draw: A table: pollutant, WHO 2005, WHO 2021, India NAAQS.
Keywords, cases and data to drop in
WHO AQG 2021, first update since 2005, PM2.5 5 µg/m³, PM10 15, NO2 10, peak-season ozone, interim targets, India NAAQS 2009 PM2.5 40, NCAP, airshed.
Where most answers lose marks
- Giving only the new numbers without the NCAP changes.
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Question text as printed in the official UPSC Civil Services (Main) question paper. The model answer is original Battle IAS work; use it to learn structure, not to memorise.
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