noxious gas
nounUK /ˈnɒkʃəs ɡæs/
US /ˈnɑːkʃəs ɡæs/
A noxious gas is a gas that is very harmful or bad to breathe.
The workers wore masks to protect themselves from the noxious gas.
OTHER MEANINGS
2. A gas that smells very bad and unpleasant.
A noxious gas filled the room after the accident.
3. A gas released by chemicals or waste that can hurt people or the environment.
The factory was fined for releasing noxious gas into the air.
4. Any gas that is dangerous to health in high amounts.
Firefighters checked for noxious gas before entering the building.