UPSC Prelims 2021 Q25: Environment & Ecology – Pollution & Waste Management
- (a) 1, 2, 3 and 5 only
- (b) 1, 2 and 4 only
- (c) 3, 4 and 5 only
- (d) 1, 2, 3, 4 and 5
Answer: (b) 1, 2 and 4 only
Explanation
Magnetite Particle Pollution Sources
| Source | Emits Magnetite? | Explanation |
|---|---|---|
| 1. Motor vehicle brakes | YES | Brake wear releases iron-oxide (magnetite) particles from brake pads and discs. Major urban PM source. |
| 2. Motor vehicle engines | YES | Diesel and petrol combustion generates magnetite nanoparticles from fuel additives and engine wear. |
| 3. Microwave stoves | NO | Microwaves heat food via electromagnetic waves; no particle emission. |
| 4. Power plants | YES | Coal-fired power plants release magnetite particles from fly ash and combustion residues. |
| 5. Telephone lines | NO | Copper telephone lines do not emit particles. |
Magnetite sources: 1, 2 and 4 only. Answer: (b).
Answer: (b) 1, 2 and 4 only.
Why each option is right or wrong
- (a) Incorrect. Microwaves and telephone lines do NOT emit magnetite particles.
- (b) CORRECT. Magnetite nanoparticles come from vehicle brakes (1), engines (2) and coal power plants (4). Suspected to cross the blood-brain barrier and contribute to neurodegenerative diseases (Alzheimer's link).
- (c) Incorrect. Neither microwaves nor telephone lines emit magnetite.
- (d) Incorrect. Microwaves (3) and telephone lines (5) do not emit magnetite.
Key point
Magnetite (Fe3O4) nanoparticle pollution = brake wear + engine combustion + coal power plants. Suspected link to Alzheimer's (crosses blood-brain barrier). NOT from microwaves or telephone lines. Answer: 1, 2 and 4.
Remember
Magnetite particles suspected of causing neurodegenerative problems come from motor vehicle brakes (1), engines (2) and power plants (4). Microwaves (3) and telephone lines (5) do not emit magnetite. Answer: (b) 1, 2 and 4 only.
Common mistakes
- Assuming any electromagnetic device emits magnetite. Only combustion and mechanical wear release magnetite particles.
- Not knowing magnetite nanoparticles can cross the blood-brain barrier - suspected link to Alzheimer's disease (Barbara Maher, 2016 research).
- Missing that brake wear is now a bigger PM source than tailpipe emissions in Bharat Stage VI-compliant vehicles.
Exam tip
Vehicle PM sources: (a) Tailpipe (regulated by BS-VI), (b) Brake wear (unregulated), (c) Tyre wear (unregulated), (d) Road dust resuspension. As tailpipe cleans up, brake/tyre share rises. EU is drafting Euro 7 to regulate non-exhaust emissions.
Sources
- Barbara Maher et al. - Magnetite Pollution Nanoparticles in the Human Brain, PNAS 2016
- WHO - Ambient Air Pollution: Health Effects (2021)