The National Ambient Air Quality Standard (NAAQS) in India for PM2.5 (24-hour average) is:

• A 25 µg/m³
• B 100 µg/m³
• C 40 µg/m³
• D 60 µg/m³ ✓

Explanation

The NAAQS (revised in 2009) for PM2.5 (particulate matter ≤2.5 µm diameter) is 60 µg/m³ for 24-hour average and 40 µg/m³ for annual mean. These are higher than the WHO guidelines (WHO 2021: 15 µg/m³ annual mean, 45 µg/m³ 24-hour mean). PM10 standard is 100 µg/m³ (24-hour) and 60 µg/m³ (annual). India's PM2.5 standards reflect a compromise considering feasibility, though most Indian cities far exceed even these standards. This distinction between Indian NAAQS and WHO guidelines is often tested.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.