Is inhalation therapy noxious to the ciliated nasal epithelium?

It is well known from in vitro studies that the functional state of the ciliary epithelium is temperature-dependent. The ciliary beat is irreversibly arrested above about 40-45 degrees C. We exposed 30 volunteers to inhalation therapy with hot moist vapour of about 50 degrees C. The functional state of the nasal mucosa was assessed by counting ciliary beat frequency and the percentage of dead and vital ciliated cells from a vital cytological sampling of the nose before and after treatment. The percentage of vital cells was the same whereas the ciliary beat frequency rose significantly. It is discussed that in the mucosal layer temperatures are not as high as in the inhaled vapour due to the air-conditioning capacity of the nose.