Abstract: For or attached to an aircrew respirator of the type having a hood with a cowl and visor enveloping at least the face of a user and a mask for delivering respirable air and oxygen to the user, means for maintaining a gas pressure within the hood but outside the mask greater than that outside the hood and means for preventing misting of a visor portion thereof, a non-respirator borne apparatus for controlling and supplying the required amounts of clean oxygen and air to the respirator in all conditions. The apparatus comprises a control unit and ducting assembly, the ducting being adapted for communication between the unit and the respirator and the control unit having a normal hood cavity supply facility, a normal mask breathable gas supply facility, and being mountable on the person remote from the respirator.