mofette
moffette

The word is used in the plural as mofette, or, following the French, mofettes.

The volcanic vents yielding the emanations are themselves called mofette.

Until being drilled, Wallender Born was therefore at least a (periodic) mofette.

Depending of the mineral content of the different vapours, mofette may be used for therapeutic purposes as well.

He said suddenly, "What's a mofette?"

Today, the balneo-technology of the dry carbon-dioxide gas-bath using frozen carbon-dioxide (dry ice) is also used to reproduce the effects of a natural mofette.

Or it could be the serene Himalayan music played by Karma Mofette in the Buddhist tradition using Tibetan instruments, followed by Bharatanatyam temple dances performed by Eva Soltes.