Air Quality Index · GS-III
Delhi records ‘very poor’ air quality on Diwali with 376 AQI ↗
Consider the following statements regarding the Central Pollution Control Board (CPCB), its statutory basis, and the Air Quality Index (AQI) framework:
- The CPCB was constituted under the Water (Prevention and Control of Pollution) Act, 1974, and the Air (Prevention and Control of Pollution) Act, 1981 extended its mandate to include air-quality functions without creating a separate body.
- Under the CPCB's AQI classification, an index value of 301–400 falls in the 'very poor' category, while values above 400 up to 500 constitute the 'severe' category.
- PM2.5 is classified as a 'coarse' particulate matter because its aerodynamic diameter exceeds 10 micrometres, making it the primary pollutant of concern in urban air quality monitoring.
Which of the statements given above is/are correct?
Explanation
Statement 1 is correct. The CPCB was constituted under Section 3 of the Water (Prevention and Control of Pollution) Act, 1974. The Air (Prevention and Control of Pollution) Act, 1981 did not create a new body — it extended the mandate of the already-existing CPCB to cover air pollution as well, adding air-quality functions under Section 16 of the Air Act. This is a commonly confused point: the Air Act broadened CPCB's scope but is not its founding statute. Statement 2 is correct. The CPCB's AQI scale runs from 0–500 and is divided into six bands. The 'very poor' band spans values from 301 to 400, and 'severe' covers 401 to 500. An AQI at or above 401 triggers the most stringent pollution-management responses under frameworks such as GRAP (Graded Response Action Plan). Statement 3 is incorrect. PM2.5 refers to fine particulate matter with an aerodynamic diameter of 2.5 micrometres or less — not coarse particles. It is precisely because PM2.5 particles are so fine that they penetrate deep into the lungs and even enter the bloodstream, making them far more hazardous than coarser PM10 particles. PM2.5 is the predominant pollutant of concern in Delhi's urban air quality, particularly during winter and firecracker-related episodes.