“防毒面具”常见的英文表达是 gas mask 。
例如：
The soldiers were equipped with gas masks to protect themselves from the poisonous gas.（士兵们配备了防毒面具以保护自己免受毒气的侵害。）
He quickly put on his gas mask when he heard the warning alarm.（听到警报声后，他迅速戴上了防毒面具。 ）