The Collaborative International Dictionary
Irrespirable
Irrespirable \Ir*res"pi*ra*ble\, a. [L. irrespirabilis: cf. F. irrespirable. See Respirable.] Unfit for respiration; not having the qualities necessary to support animal life; as, irrespirable air.
Wiktionary
irrespirable
a. Unbreathable.
Usage examples of "irrespirable".
I remember gasping a little, in an air that seemed to have been touched by the irrespirable chill of death.
The air was growing fouler and more irrespirable, with a thick, sodden quality, as if from a sediment of material rottenness.
Anything, even sudden death from the inhalation of some irrespirable atmosphere, would be better than the long confinement.