title: Mean alveolar air in a small breath.
mesh_terms: D002245:Carbon Dioxide / Q000032:analysis*; D006371:Helium; D006801:Humans; D008954:Models, Biological; D010313:Partial Pressure; D011650:Pulmonary Alveoli; D011653:Pulmonary Diffusing Capacity; D012119:Respiration; D012129:Respiratory Function Tests; D014692:Ventilation-Perfusion Ratio
chemical_list: D002245:Carbon Dioxide; D006371:Helium