What is the difference between primary and secondary pollutants?

The distinction between primary and secondary pollutants is crucial for understanding air quality. Primary pollutants are substances that are emitted directly into the atmosphere from identifiable sources, such as vehicles, industrial processes, or natural events like wildfires. These pollutants include things like carbon monoxide, sulfur dioxide, and particulate matter.

On the other hand, secondary pollutants are not emitted directly. Instead, they form in the atmosphere through chemical reactions between primary pollutants and other atmospheric components, such as sunlight or water vapor. A common example of a secondary pollutant is ozone, which forms from the reaction of sunlight with primary pollutants like volatile organic compounds (VOCs) and nitrogen oxides.

This understanding of how pollutants are classified highlights their different origins and behaviors in the environment, which is vital for regulating air quality and managing pollution effectively.