Q. Which of the following is usually not an air-pollutant?

Explanation by: Babita

The six air pollutants are carbon monoxide, lead, ground-level ozone, nitrogen dioxide, particulate matter, and sulfur dioxide.The combustion of gasoline and other hydrocarbon fuels in automobiles, trucks, and jet airplanes produces several primary air pollutants. Nitrous oxide (N2O), commonly known as laughing gas, is used in surgery and dentistry for its anaesthetic and analgesic effects.