An oxygen mask is a medical device used to deliver oxygen to a person who needs it. It covers the nose and mouth and is typically secured with elastic straps around the head. The mask is connected to an oxygen source, such as an oxygen tank or a wall outlet, through tubing. When the oxygen supply is turned on, the mask delivers a steady flow of oxygen to the person wearing it, helping to increase the level of oxygen in their blood. Oxygen masks are commonly used in hospitals, clinics, ambulances, and other healthcare settings to treat conditions such as respiratory distress, low blood oxygen levels, or during surgery or medical procedures where extra oxygen is needed. They come in different sizes to fit both adults and children, and some masks have features like adjustable straps or reservoir bags to deliver higher concentrations of oxygen when necessary.