How do primary air pollutants differ from secondary air pollutants?

Question

Quizplus · Accepted Answer

Primary air pollutants are emitted directly from a source, such as car exhaust or factory emissions, into the atmosphere. Secondary air pollutants, on the other hand, are not emitted directly. Instead, they form in the atmosphere through chemical reactions between primary pollutants and other elements, such as the formation of ozone from nitrogen oxides and volatile organic compounds in the presence of sunlight.

How Do Primary Air Pollutants Differ from Secondary Air Pollutants