A protective mask is a special covering that helps shield and safeguard your face and nose from harm or danger caused by harmful substances, germs, or pollution in the air. Full definition
She realized that although firefighters wear protective masks when fighting fires, they often do not wear masks when making a second check of the building after the fire is out. (sciencedaily.com)
Staying out of the direct line of exhaust and wearing protective masks help reduce the risk of lung disease. (health.com)