What is the colorless and odorless gas that can be toxic and is produced from incomplete combustion of fuels?

The gas produced from the incomplete combustion of fuels that is colorless and odorless, yet can be highly toxic, is carbon monoxide (CO). This gas forms when there is insufficient oxygen available for burning fuel completely. Because it cannot be detected by human senses, carbon monoxide can accumulate in enclosed spaces and pose serious health risks without obvious warning.

When inhaled, carbon monoxide binds with hemoglobin in the blood much more efficiently than oxygen, leading to reduced oxygen transport throughout the body. This can result in symptoms ranging from headaches and dizziness to severe complications like unconsciousness or death at high levels of exposure.

Unlike carbon dioxide (CO2), which is a natural byproduct of combustion but is less toxic in normal atmospheric concentrations, carbon monoxide is a much more immediate danger in poorly ventilated environments where fuel-burning appliances are used. Ozone and nitrogen dioxide are also gases produced through combustion but do not fit the description of being colorless, odorless, and highly toxic in the same way carbon monoxide does.