The Babylon Project

Morph Gas is an anesthetic gas often used by the Earth Alliance to quell rioters.[1][2]

Security forces on Babylon 5 tend to use morph gas if standard methods of handling riots involving the use of shock sticks and PPGs are proved ineffective.

This type of morph gas is highly effective against Centauri, Grome and Humans, but pak'ma'ra and Narns are quite resistant to it.[3]

When inhaled, morph gas can damage the lungs of humans, though the damage isn't necessarily permanent and can heal after a few weeks.[4]