A personal protective suit including a sealed shell equipped with connection device intended to be connected to one same pressurized air source, air distribution device having an air intake connected to the connection device, and at least one first and one second air outlet, respectively intended to supply device for delivering air to the wearer and device for ventilating the suit, wherein the air distribution device includes a valve designed to reduce the air flow rate of the second air outlet when the air pressure at the air intake is below a determined value, while maintaining the supply of air to the wearer.