Ideally, the oxygen provided via ventilation would be just enough to saturate the blood fully. In the typical adult, 1 litre of blood can hold about 200 mL of oxygen; 1 litre of dry air has about 210 mL of oxygen. Therefore, under these conditions, the ideal ventilation perfusion ratio would be about 0.95. If one were to consider humidified air (with less oxygen), then the ideal v/q ratio would be in the vicinity of 1.0, thus leading to concept of "ventilation-perfusion equality" or "ventilation-perfusion matching". This matching may be assessed in the lung as a whole, or in individual or in sub-groups of gas-exchanging units in the lung. On the other side "Ventilation-perfusion mismatch" is the term used when the ventilation and the perfusion of a gas exchanging unit are not matched.