Question

Examples of secondary air pollutant is/are?
A. Smog
B. PAN
C. O3
D. All of the above

Answer 1

Hint: Secondary pollutants are not introduced into the environment directly from the source such as power plants or vehicles; rather they are being formed in the environment when primary pollutants originating from a source interact with the molecules present in the atmosphere.

Complete answer:
Photochemical Smog is formed in the atmosphere when the ultraviolet light coming from the sun reacts with nitrogen oxides present in the environment. This smog occurs conspicuously in the warm cities that are thickly populated. It is commonly seen as a brown haze particularly in morning and afternoon time.
Ozone is a secondary pollutant having high reactivity. It forms when the sunlight reacts with the primary pollutants present in the atmosphere. The primary pollutants may be the nitrogen oxides or the hydrocarbons. Moreover, the production of ozone is catalyzed by the sun and elevated temperatures.
However, Peroxyacetyl nitrate (PAN) is a component of photochemical smog. It is produced in the atmosphere when oxidized volatile organic compounds combine with nitrogen oxide present in the atmosphere in the presence of light.

Hence, the correct answer is option (D).

Note: Any matter or energy having undesirable impacts on the environment is referred to as a pollutant. These pollutants pose hazardous effects on the useful resources. Primary pollutants are the ones that are emitted directly into the environment from a source while the secondary pollutants are formed when these primary pollutants react with the atmospheric components. These secondary pollutants are always formed in the presence of light.