primary pollutant 

in atmospheric chemistry
https://doi.org/10.1351/goldbook.P04838
A pollutant emitted directly into the air from identifiable sources (e.g. SO2, NO, hydrocarbons, etc.). Secondary pollutants, such as ozone, are generated within the atmosphere through chemical changes which occur in primary pollutants.
Source:
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2208 [Terms] [Paper]
Citation: 'primary pollutant' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.P04838 RIS BibTex EndNote
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Last revised: February 24, 2014