Does anyone know of an item (magic or otherwise) that act like a gas mask, preventing one from ingesting gasseous poisons and such?
In a 3E game, my character and another bought a Bottle of Air, some tubing, some sealing wax, and some some clothespins. That was after we found ourselves shunted through a portal from an Atlantis analog into the elemental plane of water.
It was a sequence of rather improbable events, but the dice rolled our way that night.Fortunate that you found a store on the elemental plane of water.
With all those things.
Before you ran out of air.
That was wiling to sell them for less than your net worth, under the circumstances.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.