A gas mask is a protective mask that covers your face to help you breathe clean air when there are harmful gases or pollutants in the environment. Full definition
If you have to go to work... wear gas mask or something to cover your face. (justarsenal.com)
He even had his own custom - made gas mask. (ohmidog.com)
The whole process became so disgusting that I had to prepare myself with gloves, trash bags and a make - shift gas mask. (catfooddispensersreviews.com)