What poisonous gas is produced by vehicle exhaust?

Carbon monoxide is a colorless, odorless gas that is produced when fuel is burned in vehicles. It is a byproduct of incomplete combustion, which can occur in gasoline and diesel engines when there isn't enough oxygen to fully convert carbon in the fuel into carbon dioxide.

The danger with carbon monoxide lies in its ability to bind to hemoglobin in the blood, forming carboxyhemoglobin. This reduces the blood’s ability to carry oxygen to vital organs and tissues. Prolonged exposure to carbon monoxide can lead to serious health issues, including poisoning, which can be fatal in high concentrations.

Carbon dioxide, while it is a greenhouse gas and present in vehicle exhaust as a byproduct of complete combustion, is not toxic at the levels typically encountered in exhaust fumes. Hydrogen sulfide is often associated with decaying organic matter and is not a product of vehicle exhaust, while methane is primarily released from natural gas combustion and other sources and isn't a significant component of vehicle exhaust. Therefore, carbon monoxide stands out as the most hazardous gas produced by vehicle emissions.