Which of the following is NOT regarded as a pollutant on land or in the air?

1. Analyze the question You are asked to find the one option that is NOT a pollutant. A pollutant is any substance or form of energy that harms the environment or living things when it is present in excess or in the wrong place.

2. Explain the concept Air and land pollutants include:

• Gases from burning fuels and industry (carbon monoxide, sulphur dioxide, nitrogen oxides)
• Particles (smoke, soot, dust)
• Energy pollution (noise, excess heat)
• Solid waste and chemicals on land

Nitrogen gas (N₂) is different. It makes up about 78% of clean air. It is chemically inert and harmless, and it is essential in the nitrogen cycle. Do not confuse it with oxides of nitrogen (NO, NO₂), which are pollutants that cause acid rain and respiratory problems.

3. Go through each option

• A. Smoke: a pollutant. It contains soot and harmful particles that cause respiratory illness.
• B. Nitrogen: a natural, harmless component of air, so it is not a pollutant.
• C. Noise: a pollutant (noise pollution). It causes hearing loss, stress and sleep disturbance.
• D. Sulphur dioxide: a pollutant. It comes from burning fossil fuels and causes acid rain and breathing problems.

4. Answer The correct option is B. Nitrogen.

5. Exam tip Watch the wording. "Nitrogen" is harmless, but "nitrogen oxides" are pollutants. Likewise, carbon dioxide is a natural gas but is considered a pollutant in excess, while oxygen and nitrogen are not. JAMB likes testing this difference.