Air Quality Index

Explanation

Statement 1 is correct. The CPCB was established 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 merely added air-quality regulatory functions to the CPCB (Section 16) and to the State Pollution Control Boards (Section 17). Statement 2 is correct. According to CPCB's own AQI health guidance, air in the 'Poor' band (201–300) can cause breathing discomfort to most persons on prolonged exposure — it is the health descriptor that formally accompanies that band. Statement 3 is incorrect. Temperature inversion actually worsens dispersion rather than improving it. Under normal atmospheric conditions, surface air is warmer and rises, carrying pollutants aloft and dispersing them. During a temperature inversion, a layer of warmer air sits above cooler surface air, acting as a 'lid' that suppresses vertical mixing and traps particulate matter (such as PM2.5) close to the ground. This is why inversion events, common in evenings and winter months, cause sharp spikes in AQI readings in cities with bowl-shaped terrain or surrounding hills that further obstruct horizontal airflow.

Explanation

Pair 1 is correctly matched: 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 CPCB — it merely extended CPCB's mandate to cover air pollution functions. Pair 2 is correctly matched: the CPCB describes the 'Severe' AQI category as one that affects even healthy individuals and seriously impacts those with pre-existing diseases, distinguishing it from lesser categories that primarily affect only sensitive groups. Pair 3 is incorrectly matched: the Air Act, 1981 is not the statute under which CPCB was constituted. CPCB's origin lies in the Water Act, 1974; the Air Act, 1981 added air-quality responsibilities to an already-existing body.

Explanation

India's official AQI, launched in 2014, converts measurements of up to eight major air pollutants into a single number. These eight pollutants are: PM2.5, PM10, nitrogen dioxide, sulphur dioxide, ozone, carbon monoxide, ammonia, and lead. Ammonia is indeed a gaseous pollutant included in this framework — Pair 1 is correctly matched. PM2.5 refers to fine particulate matter with a diameter of 2.5 micrometres or less; these particles are well-established as capable of penetrating deep into the lungs and entering the bloodstream, making Pair 2 correctly matched. Lead, however, is a heavy-metal particulate pollutant — not a gaseous pollutant. It is measured as airborne particulate lead, not in its gaseous form. Classifying lead as a 'gaseous pollutant' is a conceptual error — Pair 3 is incorrectly matched. Hence only Pairs 1 and 2 are correctly matched.

Explanation

Statement 1 is correct. The AQI is designed precisely to translate raw pollutant concentration data — covering eight pollutants such as PM2.5, PM10, NO2, SO2, and CO — into a single composite number, making it easy to communicate air quality conditions and associated health risks to the public. The CPCB computes sub-indices for each pollutant and takes the highest sub-index as the overall AQI. Statement 2 is incorrect. CPCB was constituted under Section 3 of the Water (Prevention and Control of Pollution) Act, 1974 — not the Air Act. The Air (Prevention and Control of Pollution) Act, 1981 merely extended CPCB's mandate to cover air pollution; it did not create CPCB. Confusing the constituting statute (Water Act, 1974) with the later mandate-extension statute (Air Act, 1981) is a classic near-miss error.

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.