UPSC Prelims 2014 Q24: Environment & Ecology – Pollution & Waste Management
Which of the following are some important pollutants released by steel industry in India?
1. Oxides of sulphur
2. Oxides of nitrogen
3. Carbon monoxide
4. Carbon dioxide
Select the correct answer
using the code given below.
- (a) 1, 3 and 4 only
- (b) 2 and 3 only
- (c) 1 and 4 only
- (d) 1, 2, 3 and 4
Answer: (d) 1, 2, 3 and 4
Explanation
Pollutants released by the steel industry
Steel is made by burning coke with iron ore and limestone in a blast furnace.
| Pollutant | Released? | Source in a steel plant |
|---|---|---|
| 1. Oxides of sulphur | Yes | Sulphur in coal and iron ore |
| 2. Oxides of nitrogen | Yes | High-temperature burning in furnaces |
| 3. Carbon monoxide | Yes | Coke reduces iron ore, giving off carbon monoxide |
| 4. Carbon dioxide | Yes | Burning of coke and breakdown of limestone |
Other pollution from steel plants:
| Type | Example |
|---|---|
| Particulate matter | Dust from sinter plants and coke ovens |
| Solid waste | Slag, used in cement and road making |
| Water pollution | Phenols, cyanides and ammonia from coke ovens |
Answer: (d) 1, 2, 3 and 4.
Why each option is right or wrong
- (a) Incorrect. Oxides of nitrogen are also released.
- (b) Incorrect. Oxides of sulphur and carbon dioxide are also released.
- (c) Incorrect. Oxides of nitrogen and carbon monoxide are also released.
- (d) CORRECT. The steel industry releases all four pollutants.
Key point
Steel industry emits oxides of sulphur and nitrogen, carbon monoxide, carbon dioxide and particulates; slag is its main solid waste.
Remember
Steel plants emit SOx, NOx, CO and CO2.
Common mistakes
- Leaving out oxides of nitrogen, formed in any high-temperature burning.
- Forgetting that carbon monoxide is produced inside the blast furnace.
- Thinking steel plants cause only dust pollution.
Exam tip
Any industry burning coal at high heat emits all the common air pollutants.
Sources
- Central Pollution Control Board — Environmental standards for the integrated iron and steel industry
- NCERT Class XII — Biology (Environmental Issues: air pollution)