Detailed Explanation:

Answer: Option 4 — 1, 2, 3 and 4

The burning of crop/biomass residue releases multiple pollutants into the atmosphere through incomplete combustion and chemical reactions. All four pollutants mentioned—carbon monoxide, methane, sulphur dioxide, and ozone—are associated with biomass burning, either as direct emissions or secondary formation.

✅ Carbon Monoxide (CO) – Released: Incomplete combustion of organic matter directly produces carbon monoxide, a toxic gas that reduces oxygen-carrying capacity in blood and contributes to air pollution.

✅ Methane (CH₄) – Released: Biomass burning releases methane, a potent greenhouse gas with 25 times the global warming potential of CO₂ over a 100-year period, contributing significantly to climate change.

✅ Ozone (O₃) – Formed: While not directly emitted, ozone forms as a secondary pollutant when nitrogen oxides (NOₓ) and volatile organic compounds (VOCs) from biomass burning react in the presence of sunlight, creating ground-level ozone.

✅ Sulphur Dioxide (SO₂) – Released: When biomass containing sulfur compounds burns, it releases sulphur dioxide, which causes respiratory problems and contributes to acid rain formation.

📝 Short Notes: Biomass Burning Emissions

• Primary Pollutants: Direct emissions include CO, CH₄, SO₂, NOₓ, particulate matter (PM2.5 and PM10), and black carbon
• Secondary Pollutants: Ground-level ozone forms when NOₓ and VOCs react in sunlight; acid rain forms from SO₂ and NOₓ reactions with water vapor
• Greenhouse Gases: Biomass burning releases CO₂, CH₄, and N₂O, contributing approximately 40% of global CO emissions and 20% of tropospheric ozone precursors
• Health Impacts: Particulate matter and toxic gases cause respiratory diseases, cardiovascular problems, and reduced visibility; CO interferes with oxygen transport in blood
• Environmental Impact: Contributes to air pollution, smog formation, acid deposition, soil nutrient loss, and climate change through greenhouse gas emissions
• Major Sources: Agricultural residue burning (stubble burning in Punjab/Haryana), forest fires, and traditional biomass fuel use for cooking and heating