- 2072 Magh · 1+3 marks
Classification of air pollutants; sources, effects
Short answer
Air pollutants are classified by origin (primary or secondary), physical state (gaseous or particulate), and source (natural or man-made). Common ones: CO from incomplete combustion causes carboxyhaemoglobin; SO₂ from coal burning leads to acid rain and respiratory illness; NOx from vehicles contributes to smog and acid rain; particulate matter from construction and vehicles triggers asthma and lung cancer.
How are air pollutants classified? State four common air pollutants, their sources and effects on the human and environment.
Classification of air pollutants
- By origin: primary pollutants are emitted directly (CO, SO₂, NO, soot); secondary pollutants form in the air by reaction of primary ones (O₃, PAN, H₂SO₄ mist, NO₂).
- By physical state: gaseous (CO, SO₂, NOx, hydrocarbons) and particulate (dust, smoke, fumes, fly ash, aerosols).
- By source: natural (volcanoes, dust storms, forest fire) and man-made (vehicles, industries).
Common air pollutants (any four)
| Pollutant | Main sources | Effects |
|---|---|---|
| Carbon monoxide (CO) | Incomplete combustion in vehicles, wood and coal fires | Combines with haemoglobin (carboxyhaemoglobin), reducing O₂ transport; headache, death |
| Sulphur dioxide (SO₂) | Burning coal and oil, smelters, brick kilns | Respiratory diseases; acid rain; damages plants |
| Oxides of nitrogen (NOx) | Vehicles, power plants, high temperature combustion | Lung irritation; photochemical smog; acid rain |
| Hydrocarbons / VOCs | Vehicle exhaust, solvents, evaporation of petrol | Photochemical smog; some are carcinogenic |
| Particulate matter (dust, smoke, PM₁₀, PM₂.₅) | Brick kilns, construction, vehicles, burning of waste and forests | Asthma, bronchitis, lung cancer; reduced visibility |
| Lead | Leaded petrol, batteries | Damages brain and nerves, especially in children |
✓ Answer checked by Claude Opus 5.5 (high effort)
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