Environmental Armor

Environmental Armor was developed for use in heavily contaminated environments, and is prized in the wasteland for its ability to protect against biological threats. This Armor affords the wearer 60% protection against harmful airborne agents and radiation. A superior version of this armor is Environmental Armor Mark II.

Eastern Brotherhood of Steel Knights are sometimes dressed in Environmental Armor. This protects them against radiation, chemical and biowarfare agents. Of course, it also helps with the Brahmin smell.

Appearances in games
Environmental armor appears only in Fallout Tactics. It was to appear in the cancelled Fallout d20 as well. It is described in J.E. Sawyer's Fallout Role-Playing Game, so it might have appeared in Van Buren as well.

The art for this armor is in Fallout 2's pro files leading one to suspect it was originally intended for that game as well.

Environmental Armor was indeed implemented in Killap's Fallout 2 Restoration Project mod. It is found in EPA and has a use in that game. See http://falloutmods.wikia.com/wiki/Main_Page, Fallout 2 Mods, for details.