What dangerous gas is given off by a running gasoline engine?

The gas produced by a running gasoline engine that poses a danger is carbon monoxide. Carbon monoxide is a colorless, odorless gas that forms during the incomplete combustion of fossil fuels, including gasoline. This means that when gasoline is burned in an engine, especially in conditions where there is insufficient oxygen, carbon monoxide can be produced.

The danger of carbon monoxide arises from its ability to bind with hemoglobin in the blood, preventing oxygen from being transported effectively. This can lead to symptoms ranging from headache and dizziness to more severe health issues, and in high concentrations, it can be lethal.

While carbon dioxide is also produced by gasoline engines, it is generally not as immediately hazardous as carbon monoxide, since carbon dioxide is a natural product of respiration and is typically present in the atmosphere in larger amounts. Ozone, on the other hand, is created by photochemical reactions involving sunlight and various pollutants, rather than being directly emitted in harmful quantities by gas engines. Nitrogen dioxide is another pollutant formed from combustion processes but is less prevalent than carbon monoxide in this specific context.