[Importance of the relative humidity values in determining thermohygrometric comfort]

A condition of discomfort with specific symptoms, such as throat dryness, eye irritation, in a group of workers of a small, air conditioned, working department, is described. Neither the measurements of the possible environmental pollutants concentrations, nor the assessment of the usually adopted comfort indexes (PMV-PPD) justified the worker's symptoms. They completely disappeared by means of appropriate environmental improvements aiming to increase the relative humidity values from 29% to 50-55% (drop of the amount of the hygroscopic material stored, setting up of an humidifier). The effects of the low humidity values on the hygrometric and thermal comfort are finally discussed.