There is provided a mass exchange apparatus (114) for use in blood/air mass exchange comprising plural blood flow conduits for defining a blood flow from a blood flow inlet provided thereto; and plural air flow conduits for defining an air flow from an air flow inlet provided thereto. The plural air flow conduits and plural blood flow conduits at least partially comprise gas-permeable membrane material, and the conduits are arranged relative to each other such as to enable transfer of oxygen from the air flow to the blood flow and transfer of carbon dioxide from the blood flow to the air flow through the membrane material.