Exhaust
Exhaust gas was the gas created by the combustion of fuel from a vehicle and emitted from its tail pipe and was a major contributor towards creating smog. 

After Tom Paris started the internal combustion engine of the 1936 Ford truck that was discovered floating in space in 2371, expelled a considerable amount of exhaust into 's cargo bay. Upon doing so, B'Elanna Torres suggested that they increase the ventilation before they became asphyxiated. ()

See also 
 Plasma exhaust

External link 
 

Chemistry