a. (UN-1 7 b, 5 b.)
1807. Aikin, Dict. Chem., II. 94/2. Foul or unrespirable air.
1836. Brande, Chem., 392. Ammonia is … acrid, and of course unrespirable.
1839. Ure, Dict. Arts, 991. The pit … is rendered unsafe … by the unrespirable gases.
