Home › PYQs › Environment › All questions › 2014 · Steel industry pollutants
UPSC Prelims 2014 · Environment · Pollution Files
Which of the following are some important pollutants released by the steel industry in India? Select the correct answer using the code given below.
- Oxides of Sulphur
- Oxides of nitrogen
- Carbon monoxide
- Carbon dioxide
- (a) 1, 3 and 4 only
- (b) 2 and 3 only
- (c) 1 and 4 only
- (d) 1, 2, 3 and 4
Show the answer and explanation
Answer: (d) 1, 2, 3 and 4
All four come from steelmaking.
Statement by statement
1. ✓ YES Sulphur in coke and ore gives SO₂.
2. ✓ YES High-temperature burning makes NOₓ.
3. ✓ YES Blast furnaces run on carbon monoxide.
4. ✓ YES Steel is one of the biggest CO₂ emitters.
The idea
Iron ore is iron joined with oxygen. To free the iron, the oxygen is pulled away with carbon, in the form of coke. That chemistry is the source of the carbon gases; the other two come from the fuel and the heat.
Coke burns → carbon monoxide → Carbon monoxide takes oxygen from the ore → iron + carbon dioxide → Sulphur in coke and ore → sulphur oxides → Very high furnace temperature → nitrogen oxides from the air
Also know
Steel is a hard-to-abate sector because the carbon is part of the chemistry, not only a fuel. One route to green steel replaces coke with hydrogen: hydrogen takes the oxygen from the ore and leaves water instead of carbon dioxide.
🔒 Steel ≈ 7–9% of global CO₂. Green steel = low-emission steel, including hydrogen DRI and scrap-based routes.