The Effect of Air Humidification on Symptoms and Nasal Patency, Tear Film Stability, and Biomarkers in Nasal Lavage: A 6 Weeks' Longitudinal Study

Abstract

Air humidification is sometimes used to reduce dryness symptoms in temperate climates, but the biological mechanism behind this effect is not well understood. We have investigated the effect of air humidification on physiological signs from the eyes and nose, other medi cal symptoms and on perceived air quality. An experi mental study was performed in two units of a well-venti lated geriatric hospital in southern Sweden. Blinded cen tral steam air humidification in one of the units during 6 weeks raised the relative air humidity to 43% RH (Janu ary-March 1997), while the other unit with 35% RH served as control. All staff (N = 32) working the day shift were invited to undergo a medical investigation per formed in the hospital units. It included measurement of tear film stability, acoustic rhinometry, nasal lavage and completing a medical questionnaire. The investigation was repeated at both units after 6 weeks and 26 subjects participated on both occasions (81 %). The technical mea surements were room temperature, relative air humidity