Question 33 from UPSC CSE 2019 - Environment

Question

Consider the following:
1. Carbon monoxide
2. Methane
3. Ozone
4. Sulphur dioxide
Which of the above are released into the atmosphere due to the burning of crop/biomass residue?

IASCODEX · Accepted Answer

Correct Option: D. 1, 2, 3, and 4

Strategy: Recognize that burning organic matter like crop or biomass residue emits a wide spectrum of pollutants. Carbon monoxide and methane are direct byproducts of incomplete and anaerobic combustion. Sulphur dioxide is also released if the residue contains sulphur. Ozone is not directly emitted but forms secondarily when precursors like methane and NOx react photochemically in the atmosphere. As all four pollutants are released directly or indirectly from burning, all statements are correct.

Key Info: Crop residue or biomass burning is a major source of air pollution, contributing to both local and regional hazes.

- Carbon monoxide (CO) is generated by incomplete combustion of organic matter and is a toxic gas affecting respiratory health.
- Methane (CH4) is released when decomposition is anaerobic, and also during low-temperature burning. It is a potent greenhouse gas with high global warming potential.
- Ozone (O3) at ground level is a secondary pollutant. Its precursors—methane, volatile organic compounds, and nitrogen oxides released during burning—lead to photochemical reactions in the lower atmosphere forming ozone.
- Sulphur dioxide (SO2) is formed when biomass containing sulphur is combusted. It contributes to acid rain and respiratory issues.

Other notable emissions include carbon dioxide, particulate matter (including black carbon and organic carbon), oxides of nitrogen (NOx), and various volatile organic compounds (VOCs), all playing roles in deteriorating air quality and impacting climate. Crop burning is particularly problematic in regions like North India, affecting visibility and public health across vast areas.

IASCODEX · Answer

Option A: 1 and 2 only

IASCODEX · Answer

Option B: 2, 3, and 4 only

IASCODEX · Answer

Option C: 1 and 4 only

Consider the following: Carbon monoxide Methane Ozone Sulphur dioxide Which of the above are released into the atmosphere due to the burning of crop/biomass residue?

Consider the following:

Carbon monoxide

Methane

Ozone

Sulphur dioxide
Which of the above are released into the atmosphere due to the burning of crop/biomass residue?