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.
Primary Pollutants
Secondary Pollutants
Carbon monoxide (CO)Oxides of nitrogen (NOx, NO) Sulfur oxides (SOx)Hydrocarbons Particulate matter (dust, ash, salt particles)