A gas mask is a mask worn over the face to protect the wearer from inhaling airborne pollutants and toxic materials. 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. It protects against inhaled chemical agents such as irritant gas or blood agents, and gives some protection against nerve agents. If worn as part of an NBC suit, the suit will provide complete protection against all chemical agents as long as it is intact.