Question

The primary pollutants are emitted directly into the atmosphere, while the secondary pollutants get formed in the atmosphere. Which of the following is an example of a secondary pollutant?

Options

• Smoke

• Smog

• Dust

• Sulphur dioxide

Answer 1

Smog

Explanation:

Smog is a secondary pollutant; it is formed in the atmosphere (for example, photochemical reactions of NOx and hydrocarbons produce ozone and PAN, and smog can result from the mixture of smoke and fog), whereas smoke, dust, and SO₂ are primary pollutants emitted directly.