Which term refers to a pollutant released directly into the atmosphere from a source?

Which term refers to a pollutant released directly into the atmosphere from a source?

• A. Secondary pollutant
• B. Greenhouse gas
• C. Primary pollutant
• D. Odorant

Answer: (C)

When pollutants enter the air directly from a source, they are described as primary pollutants. This means they’re released in their pollutant form, such as smoke, soot, sulfur dioxide, or carbon monoxide from factories or vehicles, without needing chemical reactions in the atmosphere first. In contrast, secondary pollutants form after primary pollutants react with sunlight or other chemicals in the air—like ozone created from nitrogen oxides and volatile organic compounds. Greenhouse gases describe a pollutant’s heat-trapping effect rather than how it enters the atmosphere, and odorants relate to smell rather than the release mechanism. So, the term that fits “released directly into the atmosphere from a source” is primary pollutant.

When pollutants enter the air directly from a source, they are described as primary pollutants. This means they’re released in their pollutant form, such as smoke, soot, sulfur dioxide, or carbon monoxide from factories or vehicles, without needing chemical reactions in the atmosphere first. In contrast, secondary pollutants form after primary pollutants react with sunlight or other chemicals in the air—like ozone created from nitrogen oxides and volatile organic compounds. Greenhouse gases describe a pollutant’s heat-trapping effect rather than how it enters the atmosphere, and odorants relate to smell rather than the release mechanism. So, the term that fits “released directly into the atmosphere from a source” is primary pollutant.