Aerosols are classified based on their size, formation process, and chemical composition. In terms of size, they are typically divided into three categories: nanoparticles (less than 100 nm), fine particles (100 nm to 2.5 µm), and coarse particles (2.5 µm to 10 µm). Based on formation, aerosols can be primary, directly emitted into the atmosphere, or secondary, formed through chemical reactions in the air.
