Perceived problems and discomfort at low air humidity among office workers

Abstract Dry air in office workplaces has been the target for discomfort complaints and a number of symptoms in the skin and the mucous membranes, such as eye irritation. To investigate the effects of dry ambient air, 39 office workers, working in the same building on two floors (23 on one floor and 16 on the other), were asked to participate in a study (single-blind design). The air temperature was 20–22°C during the whole 12-week test period. The relative humidity (RH) was changed from about 43%, which was the regulated normal RH of the particular office building (NORMAL), to about 15% (DRY) and was then changed back to NORMAL. Each humidity level was maintained for 4 weeks. Comfort and symptoms of the skin, eyes, mouth and throat were evaluated by a questionnaire at each RH level, and before and after each shift of air humidity. A few symptoms were already reported under NORMAL RH. 54% of the subjects reported that the air was ‘too dry’ in DRY conditions compared to 5% in NORMAL conditions. DRY resulted in more frequent perceived dryness of the mouth and throat (31% vs. 10%) and facial skin (44% vs. 15%), and more frequent symptoms of the eyes (36% vs. 8%), lips (38% vs. 10%) and running nose (46% vs. 8%) than did NORMAL. Some workers also reported sensations of heat/red skin in their faces more often in DRY conditions. Low relative air humidity resulted in more discomfort and more frequent symptoms in facial skin and the mucous membranes. This indicates that humidification of dry air most probably would reduce the number and frequency of air-related symptoms.