The atmosphere of a refrigeration space of a food transport vehicle is controlled by cooling the interior space of a preselected temperature by spraying liquid nitrogen within the space. After discontinuing the spraying, liquid nitrogen is conducted through a heat exchanger which extends across a portal communicating the space with ambient air. A ventilator (50) forces air through the portal (42) and the heat exchanger and into the space, whereby the ambient air is cooled and displaces gaseous nitrogen from the space. This creates a cold breathable atmosphere within the space to enable food to be loaded or unloaded. During the loading/unloading operation, liquid nitrogen can be conducted through an evaporator (40) disposed in the space to maintain the temperature in the space.