UPSC Prelims 2020 Q48: Environment & Ecology – Pollution
Which of the following are the reasons/factors for exposure to benzene pollution?
1. Automobile exhaust
2. Tobacco smoke
3. Wood burning
4. Using varnished wooden furniture
5. Using products made of polyurethane
Select the correct answer using the code given below:
- (a) 1, 2 and 3 only
- (b) 2 and 4 only
- (c) 1, 3 and 4 only
- (d) 1, 2, 3, 4 and 5
Answer: (a) 1, 2 and 3 only
Explanation
Sources of benzene exposure
Benzene is a carcinogenic hydrocarbon released mainly by burning fuels and organic matter.
| Factor | Benzene source? | Why |
|---|---|---|
| 1. Automobile exhaust | Yes | The largest outdoor source; petrol contains benzene and combustion releases more |
| 2. Tobacco smoke | Yes | A major indoor source for smokers and passive smokers |
| 3. Wood burning | Yes | Incomplete combustion of wood releases benzene |
| 4. Varnished wooden furniture | No (official key) | Releases other VOCs such as formaldehyde; benzene is not a notable component |
| 5. Polyurethane products | No (official key) | Linked to isocyanates and other VOCs rather than benzene |
The common thread in the correct items is combustion.
Answer: (a) 1, 2 and 3 only.
Why each option is right or wrong
- (a) CORRECT. Vehicle exhaust, tobacco smoke and wood burning are the main combustion sources of benzene.
- (b) Incorrect. It leaves out vehicle exhaust, the largest benzene source, and adds varnished furniture.
- (c) Incorrect. It drops tobacco smoke, a key indoor source, and adds varnished furniture.
- (d) Incorrect. Per the official key, varnish and polyurethane are not notable benzene sources.
Key point
Main benzene sources: vehicle exhaust (largest), tobacco smoke and wood burning, all combustion processes.
Remember
Benzene = burning: exhaust, tobacco, wood.
Common mistakes
- Treating every VOC-emitting product as a benzene source.
- Forgetting tobacco smoke as a leading indoor source of benzene.
- Choosing 'all of the above' without checking each item.
Exam tip
Benzene comes mostly from burning: fuel, tobacco and wood. Paints and foams release other VOCs.
Sources
- WHO — Exposure to Benzene: A Major Public Health Concern
- UPSC Civil Services (Preliminary) 2020 — Official Answer Key, GS Paper I