A method of controlling gas composition within a container containing respiring produce is described. The container includes at least one gas outlet and at least one gas inlet and the method includes the steps of: drawing gas from within the container through a selective membrane element under selected control conditions through the at least one gas outlet introducing ambient air from outside die container into the container through the at least one gas inlet under selected control conditions to control the relative composition of gases inside the container. Apparatus for containing the goods and for controlling the atmosphere in the container according to the method are also described.