Q. Consider the following statements regarding photochemical smog:

1. It is a type of secondary pollutant
2. It acts as a greenhouse gas
3. It contains ozone as an essential component

Which of the above statements is/are correct?
Answer: 1, 2 and 3
Notes: All the statements are correct. Photochemical smog forms as a secondary pollutant from reactions involving sunlight, contains ozone as a major component, and includes greenhouse gases like ozone which contribute to warming. Thus, photochemical smog is secondary, acts as a greenhouse gas, and has ozone as an essential component.