Concept: Air pollutants: Pollutants are classified in different ways. According to origin pollutants are two types.
1). Primary pollutants:● These are directly emitted from the sources in the atmosphere in a harmful form.● They can be natural (volcanic eruptions or fires, for example) or of anthropogenic origin (carbon monoxide from vehicles).2).
Secondary Pollutants: ● These are derived from primary pollutants due to chemical or photochemical reactions in the atmosphere they become hazardous after reaction in the air.
● The best known of the secondary pollutants is certain gases that are synthesized by photochemical reactions in the lower atmosphere.
● The primary emitted chemicals in these reactions are hydrocarbons and gaseous oxides of nitrogen such as nitric oxide and nitrogen dioxide.
● Its origin lies in the interactions between the primary emissions in the atmosphere.