Secondary Air Pollution is the pollutant not directly emitted but forms when other primary pollutants react in the atmosphere. (e.g., Ozone - formed when hydrocarbons (HC) and nitrogen oxides (NOx) combine in the presence of sunlight; NO2 - formed as NO combines with oxygen in the air; Acid rain - formed when sulphur dioxide or nitrogen oxides react with water.) The Secondary Pollutant is harder to control because of having the different ways of synthesising and the formation are not well understood.
Related Definitions in the Project: The HSE Management
