sources of air pollutants are?

Analyze the question: It asks for the sources of air pollutants, meaning things that release harmful substances into the air. We need the option where every item actually pollutes the air.

Concept: Air pollution comes from human activities and natural processes that release harmful gases, particles, and chemicals into the atmosphere. Common examples include:

• Vehicle exhaust fumes (carbon monoxide, nitrogen oxides, lead compounds)
• Industrial emissions (sulphur dioxide, smoke, particulates)
• Burning of fossil fuels and refuse
• Aerosol sprays (CFCs)

Evaluate each option:

• A. Industrial chimneys, burning fossil oils and river dams. The first two are valid sources, but river dams are not a source of air pollution. They relate to water and hydroelectric power. ❌
• B. Sulphur dioxide, acid rain and pesticides. Acid rain is a result of air pollution, not a source of it. Pesticides mainly pollute soil and water. ❌
• C. Sulphur dioxide, vehicle exhausts, and aerosols. Sulphur dioxide comes from industries and fuel burning. Vehicle exhausts release CO, NOx and other pollutants. Aerosols release CFCs and particles. All three are valid air pollutant sources. ✅
• D. Sewage, smoke and old vehicles. Sewage is mainly a water and soil pollutant. ❌

Answer: Option C is correct.

Exam tip: In pollution questions, match the pollutant to the medium it affects. Sewage and dams point to water, pesticides point to soil and water, while exhausts, smoke, SO₂ and aerosols point to air. Also watch for effects (like acid rain) being disguised as sources.