Chemical and gas grenades Chemical and gas grenades are thrown weapon s that appears in all of the " Fallout " games . Chemical and gas grenades are used to disperse chemical or gas agents , ignite targets or materiel or create smoke as a means of concealment . Due to their varied nature , different grenade models may be more effective against some targets , and less effective against others . Chemical and gas models . Chemical gas grenades are used to deliver or disperse a chemical or biological agent designed to incapacitate or kill . Although most utilize a small explosive charge to disperse the chemical agent , the mode of wounding action is through the agent not the explosive . The chemical agent is usually dispersed by the grenade in a small radius around the grenade , creating a cloud of deadly gas . This cloud of chemical agent will typically remain active for a short time , effecting anything that enters , until it dissipates . Bio - gas canister . This grenade does not explode by itself , but instead releases highly - flammable bio - gas vapors upon hitting the ground . The vapors can then be ignited from a distance with an energy or incendiary weapon , causing the leaking gas to erupt in a spectacular fireball . In this way , they function as portable gas - leaks . Added in the " Point Lookout " add - on . Cryo grenade . Cryo grenades do only one point of damage , but release frigid Liquid Nitrogen upon detonating , freezing any opponents caught in the blast , and rooting them in place for several seconds . Added in the " Mothership Zeta " add - on . Mirelurk bait grenade . Mirelurk bait grenades were to be in " Fallout 3 " , but have since been cut from the game . They would ' ve been used to draw mirelurks to the point where they detonated . This allowed you to either distract them , or to lure them into a trap . Gas grenade . A non - lethal grenade that lets out a cloud of gas / smoke upon detonation . Whether it was to be used as smokescreen cover or flammable gas is unknown . Acid grenade . Acid grenades spray a sticky , corrosive substance upon detonation , dissolving anything caught in its blast . They appear to have increased effectiveness against the metal shells of robotic opponents . Boom bug . Boom bugs are mutant ladybugs that are used as improvised toxic grenades . When thrown , upon impact , they explode releasing a cloud of poison gas in the immediate area . Chemical grenade . The chemical grenade was a combination of the acid grenade and the cut smoke grenade . The gas released was designed to be horribly toxic against organic targets . Powder bag . Powder bags are improvised thrown weapons that act as stun grenades . They are small bags filled with a chemical powder that can stun the target when the powder is released through the cloth of the bag . Tangle grenade . The tangle grenade was designed to be able to ensnare personnel with a tangler polymoid . It was planned to be in " Fallout Tactics " , but was never added . Toxic grenade . This grenade does very little damage initially , but releases a cloud of poisonous vapours upon detonation , inflicting Poison Damage over time to anyone caught in its blast . Bio grenade . Not much is known about this model of bio grenade . While present in the game files of " Van Buren " , it is effectively unusable so its exact effects are unknown . It can be assumed that it was to release some kind of biological agent upon detonation . BITE - ME tear gas . Tear gas grenades are non - lethal chemical gas grenades used for riot control . They use a noxious chemical agent that irritates the mucous membranes in the eyes , nose , mouth and lungs to induce tears , pain , difficulty breathing , vomiting or even blindness . Incendiary models . Incendiary grenades are used to ignite objects with the intense heat created by a chemical reaction . Typically , the reaction is created by aluminum metal and iron oxide , or by the reaction of white phosphorus and air . Incendiary grenades are usually much more effective against unprotected organic targets . AN - 205 incendiary grenade . The incendiary grenades that appears in the Mojave Wasteland , release a blast of burning material on detonation , making it especially effective against fleshy foes . Super mutants and robots are significantly less affected by the blast . Incendiary grenade . Incendiary grenades release a blast of burning material on detonation , making it especially effective against fleshy foes . Super - Mutants and Robots are significantly less affected by the blast . Smoke models . Smoke grenades are used as both signaling devices and to provide concealment . A chemical reaction of different agents , when mixed and ignited , produce either colored smoke as a signaling device , or a dense cloud of chemical smoke to screen for concealment . Smoke grenade . The smoke grenade was planned to be used in " " , but was cut . Smoke grenades were also planned for " " , but didn ' t make the cut either .