A pollutant formed in the atmosphere rather than emitted directly is known as a

A pollutant formed in the atmosphere rather than emitted directly is known as a

• A. Secondary air pollutant
• B. Primary air pollutant
• C. Ambient pollutant
• D. Toxic pollutant

Answer: (A)

Secondary air pollutants are formed in the atmosphere after pollutants are released, through chemical reactions driven by sunlight, oxygen, and moisture. For example, ozone a pollutant in the lower atmosphere is produced when nitrogen oxides and volatile organic compounds react in sunlight. Sulfate and nitrate particles form from sulfur dioxide and nitrogen oxides, respectively, via atmospheric oxidation, becoming fine particulate matter. Because these substances are created by atmospheric chemistry rather than being emitted directly, they fit the concept of secondary pollutants. In contrast, primary air pollutants are emitted directly into the air, ambient pollutant is a general term for anything present in the air (whether formed or emitted), and toxic pollutant refers to hazard, not how the pollutant is formed.

Secondary air pollutants are formed in the atmosphere after pollutants are released, through chemical reactions driven by sunlight, oxygen, and moisture. For example, ozone a pollutant in the lower atmosphere is produced when nitrogen oxides and volatile organic compounds react in sunlight. Sulfate and nitrate particles form from sulfur dioxide and nitrogen oxides, respectively, via atmospheric oxidation, becoming fine particulate matter. Because these substances are created by atmospheric chemistry rather than being emitted directly, they fit the concept of secondary pollutants. In contrast, primary air pollutants are emitted directly into the air, ambient pollutant is a general term for anything present in the air (whether formed or emitted), and toxic pollutant refers to hazard, not how the pollutant is formed.