asphyxiatorn.

/asˈfɪksɪeɪtə/Etymology: noun of agent formed as asphyxiation n.: see -ator suffix.
1882 31 Oct. 5/3 Portable fire engines or asphyxiators on every car.
This entry has not yet been fully updated (first published 1885; most recently modified version published online December 2018).