Gasmask

"An item intended to protect the user from toxic gas and radiation."

- Inventory description

"A gas mask is worn over the face to protect the wearer from inhaling airborne pollutants and toxic materials. The mask forms a sealed cover over the nose and mouth, but may also cover the eyes and other vulnerable soft tissues of the face. During the blowouts, the air becomes polluted, and you need to wear gasmasks, otherwise you will get radiation infection, and you will die in a few minutes.  It can be useful in underground areas too, since they were locked down a long time ago."

- Inventory description

Bugs
As of version 1.003, the item does nothing: toxic gas doesn't harm the player even without a gasmask on.