According to the Environmental Protection Agency (EPA), which one of the following is the largest source of sulphur dioxide emissions ?
- (a) Locomotives using fossil fuels
- (b) Ships using fossil fuels
- (c) Extraction of metals from ores
- (d) Power plants using fossil fuels ✓ UPSC's answer
Why the answer is (d)
• According to the US Environmental Protection Agency, the largest source of sulphur dioxide (SO₂) in the atmosphere is the burning of fossil fuels by power plants and other industrial facilities, since coal and oil contain sulphur that is oxidised on combustion — option (d).
• Smaller sources include industrial processes such as extracting metal from ore, and vehicles, locomotives and ships burning high-sulphur fuel.
• SO₂ causes respiratory harm, forms fine particulate matter and acid rain, and is why flue-gas desulphurisation is mandated for Indian thermal plants.
• Hence option (d).
Why the other options are wrong
- (a) Locomotives using fossil fuels
- Locomotives are a minor SO₂ source compared with power plants.
- (b) Ships using fossil fuels
- Ships are a significant but smaller source than power plants.
- (c) Extraction of metals from ores
- Metal extraction is a secondary source; power plants dominate.
Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2024, held on 16 June 2024. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.