What is the poisonous gas produced by internal combustion engines?

Internal combustion engines produce carbon monoxide as a byproduct of the combustion process. This gas is formed when fuel does not burn completely due to insufficient oxygen supply. Carbon monoxide is colorless, odorless, and highly toxic, which makes it particularly dangerous as it can be inhaled without immediate realization of the risk involved.

In contrast, carbon dioxide, while also a byproduct of combustion, is not poisonous, though it can be harmful in high concentrations as it displaces oxygen. Carbon trioxide is not a recognized compound associated with combustion processes. Carbon techrocloride does not relate to standard internal combustion engine emissions. Thus, carbon monoxide is the relevant and harmful gas emitted by these engines, highlighting the importance of adequate ventilation and monitoring in environments where internal combustion engines operate.