The National Ambient Air Quality Standards (NAAQS) in India for PM2.5 are set at what 24-hour average concentration (µg/m³)?

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

Explanation

India's National Ambient Air Quality Standards (NAAQS) revised in 2009 by CPCB set PM2.5 standards at: Annual average = 40 µg/m³; 24-hour average = 60 µg/m³. These are significantly higher than WHO Air Quality Guidelines 2021 which recommend PM2.5 annual mean ≤5 µg/m³ and 24-hour mean ≤15 µg/m³. For PM10, India's NAAQS are 60 µg/m³ annual and 100 µg/m³ 24-hour. This discrepancy between India's NAAQS and WHO standards is relevant contextually — India's standards reflect feasibility constraints, not optimal health protection levels.

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

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