Which of the following is a secondary air pollutant?

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Multiple Choice

Which of the following is a secondary air pollutant?

Secondary pollutants are formed in the atmosphere from chemical reactions after emissions. PM2.5 fits this idea because a large part of these fine particles forms when precursor gases such as sulfur dioxide, nitrogen oxides, ammonia, and volatile organic compounds react in air to produce sulfate, nitrate, and organic aerosol particles. These particles aren’t just released as dust or smoke; they are created in the atmosphere, which is the essence of a secondary pollutant. The other substances listed are typically released directly from sources as gases or soot (primary pollutants), though ozone is also formed secondarily by photochemical reactions; the emphasis here is on the particulate matter that becomes secondary through atmospheric chemistry.

Secondary pollutants are formed in the atmosphere from chemical reactions after emissions. PM2.5 fits this idea because a large part of these fine particles forms when precursor gases such as sulfur dioxide, nitrogen oxides, ammonia, and volatile organic compounds react in air to produce sulfate, nitrate, and organic aerosol particles. These particles aren’t just released as dust or smoke; they are created in the atmosphere, which is the essence of a secondary pollutant. The other substances listed are typically released directly from sources as gases or soot (primary pollutants), though ozone is also formed secondarily by photochemical reactions; the emphasis here is on the particulate matter that becomes secondary through atmospheric chemistry.

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