Nurses advancing through a cloud of smoke in a gas mask drill of the U.S. Army Air Forces Technical Training Command, Scott Field, Illinois, 1942. The gas mask is a mask used to protect the wearer from inhaling airborne pollutants and toxic gases. The mask forms a sealed cover over the nose and mouth, but may also cover the eyes and other vulnerable soft tissues of the face. Some gas masks are also respirators, though the word gas mask is often used to refer to military equipment.