1. CH4
(hydrocarbons) -- primary
pollutant
2.
NO2 (nitrogen dioxide) -- primary pollutant
3. O3
(Ozone) -- secondary pollutant
A primary
pollutant is an air pollutant emitted directly from a source while a secondary
pollutant is not directly emitted but forms when other pollutants (primary
pollutants) react in the atmosphere.
