Question

Which among the following is the secondary pollutant?
1. Smog
2. Carbondioxide
3. Carbon mono-oxide
4. Fly ash

Answer 1

Correct Answer - Option 1 : Smog

The correct answer is Smog.

• Smog is basically derived from the merging of two words-smoke and fog.
• Secondary pollutants are pollutants which form in the atmosphere. These pollutants are not emitted directly from a source.
• Smog is a secondary pollutant.
• Smog is a yellowish or blackish fog formed mainly by a mixture of pollutants in the atmosphere which consists of fine particles and ground-level ozone.
• It occurs mainly because of air pollution.
• Today, most of the smog we see is photochemical smog.
• Photochemical smog is produced when sunlight reacts with nitrogen oxides and at least one volatile organic compound (VOC) in the atmosphere.
• These VOC, SO₂, and NO_x are called precursors.
• The main sources of these precursors are pollutants released directly into the air by gasoline and diesel-run vehicles, industrial plants and activities, and heating due to human activities.
• During the winter months when the wind speeds are low, it helps the smoke and fog to become stagnate at a place forming smog and increasing pollution levels near the ground closer to where people are respiring.
• It hampers visibility and disturbs the environment.