Which statement best distinguishes a primary air pollutant from a secondary air pollutant?

Question

Accepted Answer

A primary pollutant enters the atmosphere directly, whereas a secondary pollutant forms in the atmosphere through chemical reactions.

Answer

A primary pollutant is always natural, whereas a secondary pollutant is always human-made.

Answer

A primary pollutant occurs outdoors, whereas a secondary pollutant occurs indoors.

Answer

A primary pollutant affects only humans, whereas a secondary pollutant affects ecosystems.

Crowdly