0 a device worn over the face to prevent you from breathing in poisonous gases --
1 a device a person wears over the face to protect against breathing in poisonous gases --
The gas mask referred to will give protection for at least 15 minutes against the highest concentrations of gas ever likely to be encountered.
There are problems about instruction in the fitting and use of the gas mask.
In my own division we have villages which have not yet received a single gas mask.
Again, with regard to the use of gas, each of us at the beginning of the last war was furnished with a gas mask.
If the gas mask had remained an expensive instrument of special manufacture, we could not have overcome our problem.
Four gas mask storage centres are now established.
The presence or absence of a good gas mask might be a matter of life or death.
Both of those are very difficult from behind a gas mask.
