Experimental studies of the human nasal air-conditioning capacity.

Nasal air-conditioning capacity was measured in human subjects by a method reported in 1977, which enables determinations to be made in each nasal cavity separately without introducing a foreign occluding structure between the soft palate and the posterior pharyngeal wall. The enthalpy for vaporization and for the warming of the air and the water vapour can be calculated separately. The error due to the escape of air from the lower airways, measured with both carbon dioxide and helium as tracer, was found usually to be about 1%, but sometimes greater. By varying the air flow through the relevant nasal cavity it was found that the maximum air conditioning capacity had still not been reached at 7 l/min. However, the patient suffered discomfort at flows in excess of 5 l/min. The nasal air conditioning capacity was lower at night than in the daytime. The total enthalpy and vaporization decreases with age.