A disposable or reusable mask worn over the nose and mouth for hygiene, illness prevention, or pollen protection. In everyday Japanese, マスク alone is more common, but 衛生マスク explicitly emphasizes sanitary use.
Since a cold is going around, please wear a face mask.
Wearing a surgical mask is mandatory in the hospital.
Compound of 衛生 (hygiene, sanitation) and マスク (mask, from English).