Correct Answer - Option 4 : Smog
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.
Examples of primary and secondary air pollutants:
Primary Pollutants
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Secondary Pollutants
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Carbon monoxide (CO)
Oxides of nitrogen (NOx, NO)
Sulfur oxides (SOx)
Volatile organic compounds (VOCs) highly
Particulate matter (dust, ash, salt particles)
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Ozone
PAN
Smog
Formaldehyde
Sulphuric Acid
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