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.