asphyxiative
/ˌæsfɪɡˈzɪætɪv/; /ˌæsfɪɡˈzɪvətɪv/Definitions
1. adjective
causing or tending to cause asphyxiation
“The toxic gas was asphyxiative, and anyone entering the room would have been at risk of immediate harm.”
2. noun
a substance or condition capable of causing asphyxiation
“The hospital warned of the asphyxiative effects of inhaling the fumes from the chemicals.”