Basics of Environment and Pollution Control
This domain tests ecosystems, biodiversity, pollution sources and control, waste management, environmental legislation and climate concepts. Expect matching-type facts, standard limits and simple BOD/COD or dilution calculations.
Core rules and concepts
- Pollution: air pollutants include PM2.5, PM10, SO₂, NOₓ, CO and O₃; water pollution is measured by BOD, COD, DO and pH; noise is measured in dB, a logarithmic scale.
- Standards and institutions: CPCB sets and monitors national ambient standards. The Water Act 1974, Air Act 1981 and Environment Protection Act 1986 are core legislation. EIA is governed by the EIA Notification 2006.
- AQI categories: Good 0–50, Satisfactory 51–100, Moderate 101–200, Poor 201–300, Very Poor 301–400, Severe 401–500. AQI is computed from sub-indices, not a simple average.
- Waste and climate: apply reduce-reuse-recycle; CFCs deplete stratospheric ozone; CO₂, CH₄, N₂O and fluorinated gases are greenhouse gases.
Worked example
A diluted sample has initial DO 8.0 mg/L and final DO 3.0 mg/L after 5 days. The sample fraction is 20% (0.20). BOD₅ = (8.0 − 3.0)/0.20 = 25 mg/L. The dilution factor must be applied; otherwise the result is only the DO depletion.
Traps
Treating BOD and COD as identical, forgetting the dilution factor, reading AQI as an average, and confusing ozone-layer depletion with ground-level ozone pollution.