1. Pollutants present

Among all the compounds present in the air, a simple classification can be proposed including :

• primary pollutants from specific sources (natural emissions, road traffic, agricultural, industrial or domestic waste, etc.) such as particulates, sulfur, nitrogen or carbon oxides, VOCs, etc;

• secondary pollutants resulting from natural transformation reactions of compounds present in the air (ozone, nitrogen dioxide, etc.).

Atmospheric pollutants can also be classified according to their impact on the environment