Which term refers to pollutants formed as a result of chemical reactions in the atmosphere?

• A. Primary Pollutant
• B. Secondary Pollutant
• C. Particulate Matter
• D. Smog

Answer: (B)

Secondary pollutants are created through chemical reactions in the atmosphere rather than being released directly. When primary pollutants like sulfur dioxide, nitrogen oxides, and volatile organic compounds are present in sunlight and appropriate conditions, they react to form new pollutants such as ground-level ozone, sulfates, and nitrates. This in-air formation is what defines a secondary pollutant. In contrast, primary pollutants are the substances emitted directly, and particulate matter is a broad category that can include both primary and secondary particles. Smog describes a harmful mixture that often contains secondary pollutants, but the specific term for pollutants formed by atmospheric reactions is secondary pollutant.