• # question_answer Pollutants can be classified as primary and secondary. Which of these is/are primary pollutant? 1. Volatile Organic Compounds 2. Ground Level Ozone 3. Acid Rain Select the correct answer using the codes given below. A)  1 only B)  1 and 2 only C)  1 and 3 only D)  1, 2 and 3

[a] A primary pollutant is an air pollutant emitted directly from a source. A secondary pollutant is not directly emitted as such, but forms when other pollutants (primary pollutants) react in the atmosphere. Ground Level Ozone is a "secondary" pollutant because it is produced when two primary pollutants react in sunlight and stagnant air. These two primary pollutants are nitrogen oxides $(NOx)$ and volatile organic compounds (VOCs). Acid rain is a secondary pollutant.