Question

compare primary and secondary pollutants. which is more harmful?

Explanation:

Primary pollutants are emitted directly into the environment, like sulfur - dioxide from coal - burning. Secondary pollutants form through chemical reactions in the atmosphere, such as ozone which is formed from nitrogen oxides and volatile organic compounds reacting in sunlight. It's hard to simply say which is more harmful as it depends on the pollutant and the exposure scenario. Some primary pollutants like particulate matter can cause immediate respiratory issues, while secondary pollutants like ozone can damage plants and also harm human health over time.

Answer:

It's not straightforward to determine which is more harmful as both primary and secondary pollutants have significant and different impacts on the environment and human health depending on the specific pollutant and exposure conditions.