A positive-pressure respirator is a type of respiratory protection device in which positive air pressure is maintained within the facepiece while the device is in use and being worn properly. Air pressure within the facepiece is defined as positive when it is greater than the ambient air pressure within which the mask exists. The most common type of positive-pressure respirator is a pressure-demand respirator, which supplies air to the facepiece in response to a decrease in pressure due to breathing or a breach in the facepiece. Positive-pressure respirators provide a higher degree of protection than other types of respirators, as they prevent the intake of contaminants into the facepiece due to negative-pressure airflow.