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

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)

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विश्व स्वास्थ्य संगठन (डब्ल्यू.एच.ओ.) द्वारा हाल ही में जारी किए गए संशोधित वैश्विक वायु गुणवत्ता दिशानिर्देशों (ए.क्यू.जी.) के मुख्य बिंदुओं का वर्णन कीजिए। विगत 2005 के अद्यतन से, ये किस प्रकार भिन्न हैं ? इन संशोधित मानकों को प्राप्त करने के लिए, भारत के राष्ट्रीय स्वच्छ वायु कार्यक्रम में किन परिवर्तनों की आवश्यकता है ? (150 शब्दों में उत्तर दीजिए)

The question as printed in the 2021 General Studies paper

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Model answer

Drafted with AI by UPSC Answer Check against this question's marking rubric, to the 150-word length. UPSC does not publish answers for Mains — this is one way to score well, not an official key. How we build rubrics and answers.

(a) Key points of the 2021 AQGs: Annual limits were lowered: PM2.5 to 5 µg/m³, PM10 to 15 and NO2 to 10. Short-term guidelines were revised: a new CO 24-hour value of 4 mg/m³, a new O3 peak-season value of 60 µg/m³ (8-hour 100 unchanged), and SO2 24-hour relaxed to 40 µg/m³.

(b) Difference from 2005: The 2005 values were PM2.5 10, PM10 20 and NO2 40 µg/m³. The revision reflects stronger evidence that even low exposure causes mortality and morbidity, and adds good-practice statements on black carbon, ultrafine particles and sand and dust storms.

(c) Changes needed in NCAP: NCAP targets up to 40% PM10 reduction by 2025-26 in 131 cities, a process-oriented target. India's NAAQS for annual PM2.5 (40 µg/m³) is eight times the WHO value. NCAP should adopt phased WHO-aligned standards, add PM2.5 and outcome-based targets, expand monitoring beyond 131 cities, mandate sectoral emission inventories and strengthen CPCB-SPCB enforcement, with tighter industrial and vehicular (BS-VI) norms and measures against crop-residue burning.

How this answer will be evaluated

Framework: GS3 Environment: threat, causes, impact, mitigation

What earns full marks: Precise comparison of 2005 vs 2021 values with specific NCAP policy shifts.

Evaluation rubric

Each sub-part is marked on its own, against the marks and word limit printed on the paper.

The answer Key points of revised AQGs, differences from 2005, and required changes in NCAP. 10 marks · 150 words

describe— define → structure or process in order → labelled diagram → significance
Must cover
- Mentions specific pollutants (PM2.5, PM10, NO2, O3, SO2, CO)
- Notes the drastic reduction in guideline values (e.g., PM2.5 annual mean)
- Identifies NCAP's current focus (131 non-attainment cities) vs global standards
- Suggests specific NCAP changes (stricter targets, source-specific measures)
Loses marks
- Vague generalities about 'pollution control' without specific pollutants
- Failing to distinguish between 2005 and 2021 guidelines
- Ignoring the specific requirement for NCAP changes
Earns more
- Mentions the 2021 revision date
- References specific NCAP actions (e.g., dust control, vehicle norms)
- Notes the gap between current Indian standards and WHO guidelines
- Mentions the health impact of the new guidelines
Extra mark
- Cites specific numerical values for the new PM2.5 guideline
- Mentions the 'National Clean Air Programme' (NCAP) launch year (2019)

What "Describe" is asking you to do

Give a full, ordered account of the thing named — its parts, stages or mechanism — in the sequence in which it actually exists or occurs. Most describe questions come from the science optionals, where the marks sit in correct technical detail and, where the stem says so, a labelled diagram.

Structure that answers it

One-line identification of the subject → the parts or stages in their real order, each with its defining detail → labelled diagram where the subject is structural → closing line on function or significance

Where marks are lost

Loose general prose where the examiner is ticking named parts, correct terminology and their sequence; and in the General Studies papers, turning to evaluation before the description is finished.

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