Pollution
Pollution questions sort by medium — air, water, soil, noise — and each medium has its own monitoring index and standard-setting body. Learn the AQI bands and the CPCB-SPCB split, because those are what get tested.
Mental model
Pollution is one template repeated four times: MEDIUM (air, water, soil, noise) → key pollutant → the measurable INDEX → the classic disease or damage. Air/particulate matter/Air Quality Index/respiratory disease. Water/sewage and effluent/biochemical oxygen demand/water-borne disease. Soil/heavy metals and plastics/none standard/crop contamination. Noise/decibels/hearing loss. Fill the four cells and the topic is done.
Associations
A short trigger on the left, everything it pulls with it on the right.
CPCB sets, SPCB enforces.
The Central Pollution Control Board, under the Ministry of Environment, sets national standards and coordinates state boards. The Gujarat Pollution Control Board enforces those standards within the state, issues consent to industries, and monitors compliance.
Good, satisfactory, moderate, poor, very poor, severe.
Six named bands make up India's National Air Quality Index, built mainly from PM2.5, PM10, ozone, and a few gaseous pollutants. Knowing the band names in order lets you answer any question that gives a numeric range or a health-effect description.
Things to remember
The night-before list. Short enough to recall cold.
- 1The Air (Prevention and Control of Pollution) Act was passed in 1981 and the Water Act in 1974; the Environment (Protection) Act, an umbrella law, came in 1986 after the Bhopal gas tragedy.
- 2PM2.5 refers to particulate matter smaller than 2.5 micrometres, small enough to penetrate deep into the lungs and bloodstream.
- 3The Central Pollution Control Board operates under the Ministry of Environment, Forest and Climate Change; state pollution control boards operate under state law.
- 4Gujarat's industrial belt around Vapi and Ankleshwar has historically ranked among India's most polluted industrial clusters, prompting stricter effluent norms.
- 5Noise pollution limits in India are set differently for industrial, commercial, residential and silence zones, with tighter limits at night.
In detail
- PM2.5 means particulate matter of diameter 2.5 micrometres or less; it is more dangerous than PM10 because it penetrates deep into the lungs and bloodstream.
- India's Air Quality Index runs from 0 to 500 in six categories from Good to Severe, and is reported on the single worst pollutant at that time.
- High biochemical oxygen demand indicates heavy organic pollution in water, because decomposing organic matter consumes dissolved oxygen and suffocates aquatic life.
- Eutrophication is nutrient enrichment of water, usually from fertiliser runoff and sewage, causing algal blooms and oxygen depletion.
- The Central Pollution Control Board at the national level and State Pollution Control Boards in the states are the statutory bodies that monitor and enforce pollution standards.
Where people slip
- The Central Pollution Control Board sets standards; it does not itself issue industrial consent within a state — that is the state board's job.
Check yourself
Nothing here is scored — it will not change your mastery figures.
PM2.5, used in air quality monitoring, refers to particulate matter of diameter smaller than:
From the question bank
Which pollutant is primarily measured by the Air Quality Index (AQI) and is a major concern in Indian cities during winter, consisting of fine particles less than 2.5 micrometers in diameter?
From the question bank
'Biochemical Oxygen Demand (BOD)' is used as an indicator of which of the following?
Books to read
- Environment for Civil Services — Shankar IAS Academy
- NCERT Class XII — Biology
- India Year Book — Publications Division, Government of India
Official sources
Hand-checked official domains only — the notes above carry no links of their own.