Question

Which of the following is an example of a secondary pollutant?

• A. Sulfur dioxide
• B. PAN (Peroxyacetyl Nitrate)
• C. Lead
• D. Carbon monoxide

Answer 1

Answer:

B. PAN (Peroxyacetyl Nitrate)

• Correct Answer: Option B - PAN) Peroxyacetyl Nitrate

• Air pollutants are categorized into two main types:

• Primary pollutants: These are substances that are directly emitted into the atmosphere from sources such as vehicles, factories, or natural processes. Examples include:

• Sulfur dioxide (SO₂) - released from burning fossil fuels containing sulfur

• Carbon monoxide (CO) - emitted from incomplete combustion of fuels

• Lead (Pb) - historically from leaded gasoline and still from some industrial processes

• Secondary pollutants: These are not emitted directly but are formed in the atmosphere when primary pollutants react with each other or with other atmospheric components (often through photochemical reactions involving sunlight). Examples include:

• PAN (Peroxyacetyl Nitrate) - formed when nitrogen oxides and volatile organic compounds react in the presence of sunlight

• Ozone (O₃) at ground level - formed when nitrogen oxides and volatile organic compounds react in sunlight

• Sulfuric acid (component of acid rain) - formed when sulfur dioxide oxidizes in the atmosphere

• PAN (Peroxyacetyl Nitrate) is a classic example of a secondary pollutant because it is not directly emitted from any source but forms through photochemical reactions in the atmosphere. It is a component of photochemical smog and can cause eye irritation and respiratory problems.