The Environmental Suit is a Strife item that protects the user from toxic water and radiation, and gives total immunity to the Player's/Crusader's flamethrower. Toxic water can generally be found in the Sewers. When exposed to toxic water and/or radiation for more than 30 seconds, you start taking damage (which can be reduced by armor) directly proportional to the time you are exposed past the initial 30 seconds. Using an environmental suit would be similar to having not been exposed to the poison at all. However, if you had already started taking damage, it will not prevent that damage that prolonged exposure to poison will normally have.
Poison exposure/radiation is noticed by the flashing green tint (in the original EXE; a green cast in ZDoom) on the screen. Once 30 seconds have passed, the screen stops flashing and it becomes totally green where you start taking damage. You will stop taking damage when the screen starts to flash green again.
You can hold a maximum of five suits. It lasts for 80 seconds.
The armor store in town sells these for 25 coins per unit.