The gas grenade Ben used in ("The Man Behind the Curtain")
In the Purge, the Hostiles used a toxic gas to kill the DHARMA staff on the Island. Ben used a gas grenade to kill his father in the DHARMA van. The delivery method at the Barracks is not known. The gas causes severe coughing and bleeding from the nose, leading to death shortly thereafter. The grenades are labeled "...431CTP; ...ARGE GAS". The Hostiles protected themselves from the gas by using gas masks.
A poison warning label can be seen running up the side of the can with a skull and crossbones at the bottom. The poison label consists of a message in large letters over a message in small latters. The visible characters in the large message are "D-------SON". The visible portions of the small message are "CONTE----OSED." ("The Man Behind the Curtain")
In December 2004, Charlotte and Daniel sneaked away from Jack's group on the beach, making their way to the Tempest, where they ostensibly prevented a toxic gas from being released on the island. Harper had appeared to Juliet, claiming that Ben wanted the latter to stop them from releasing the gas, but she was unsuccessful in doing so, and the fact that everyone survived afterwards indicates that it was more likely Ben who wanted to release the gas, as Charlotte suggested. ("The Other Woman")
- The gas grenade prop used in the van was a repainted "ALSG272 Continuous Discharge, Smoke Grenade, CS" device. This same device was used without repainting in "Left Behind".
- CTP is an abbreviation for the MIT Center for Theoretical Physics.
- CTP is also an abbreviation for Critical Temperature and Pressure.
- On the computer screen in the Tempest station is a list of chemicals, O-Ethyl O-(2-diisopropylaminoethyl) methylphosphonite and N,N-diisopropyl-2-aminoethane thiol, which are the immediate precursors for VX nerve gas (screencap). Thionyl chloride is also shown, and is used to make G series nerve gas. Arsenic trichloride is also shown, as well as benzilic acid.