Which of the following is called secondary air pollutant?

The correct answer is Both 1 and 2.

Key Points

• Primary vs. Secondary Air Pollutants
  • Primary Air Pollutants are emitted directly from a source.
  • Examples:- Carbon Monoxide (CO), Sulfur dioxide (SO₂), and Nitrogen oxides (NOx).
  • Secondary Air Pollutants are not emitted directly but form in the atmosphere when primary pollutants react or interact.
  • Examples:- Ozone (O₃), peroxyacetyl nitrate (PAN), and certain particulates.

Additional InformationSecondary Air Pollutants:

• Peroxyacetyl Nitrate (PAN):
  • PAN is a component of photochemical smog.
  • It forms in the atmosphere through the reaction of volatile organic compounds (VOCs) and nitrogen oxides (NOx) in the presence of sunlight.
• Ozone (O₃):
  • Ozone at ground level (tropospheric ozone) is a major component of smog.
  • It forms when nitrogen oxides (NOx) react with VOCs in the presence of sunlight.