Question

Select the option(s) which is/are NOT considered as primary air pollutant(s).

• A. Suspended particulate matter
• B. Oxides of nitrogen
• C. Volatile organic compounds
• D. Peroxyacetyl Nitrate

Hint:

Shortcut: Primary = directly emitted, Secondary = formed later. Remember PAN, ozone, and photochemical smog are classic secondary pollutants.