Sick building syndrome symptoms caused by low humidity

Sick building syndrome (SBS) symptoms were investigated in a laboratory study of low humidity environments: 30 subjects were exposed to clean air at 22C with 5%, 15%, 25% and 35% RH and 30 were exposed to polluted air at 18C, 22C and 26C with a constant moisture content of 2.4 g/kg dry air and at 22C/35%RH. The subjects were exposed to each condition for 5 h and reported the intensity of SBS symptoms. Five hours of exposure to clean air at 5% RH caused only eye symptoms, while 5 h of exposure to polluted dry air at 15% RH aggravated a number of symptoms of the skin, nose, throat and lips. Increasing indoor air temperature from 18C to 26C aggravated nose and throat symptoms and the sensation of dryness. The effect of low humidity was found to have significant effects on SBS mainly for the environmentally sensitive subjects.