Breathing equipment comprising a closed circuit and a hood which surrounds the head of the wearer and is closed at the neck. An oronasal mask is located in the hood and is connected with an air supply. Chemical oxygen generation is effected via potassium dioxide. In order to avoid air losses from the closed circuit into the hood the oronasal mask is equipped with a valve. In the normal state the valve is closed. The valve connects the interior of the mask with the interior of the hood. On reduced pressure inside the oronasal mask the valve opens, so that the hood acts like an emergency auxiliary respiratory vessel.
