Secondary pollutants can be classified by the source of pollution,such as the stationary source or the mobile source.

Secondary Pollutants

Pollutants that are not emitted directly into the air; they form in the atmosphere when primary pollutants react chemically with other substances.

Stationary Source

Fixed locations or sites that release pollutants into the environment, such as factories, power plants, and refineries.

Mobile Source

Mobile source refers to any non-stationary source of air pollutants, such as vehicles, planes, and ships, contributing significantly to air pollution.