[Humidifier syndrome as occupational disease in Switzerland]

Control of humidity may be necessary in various industrial processes. Contamination of humidifiers by algae and bacteria may lead in exposed workers to two distinct syndromes: extrinsic allergic alveolitis and humidifier fever. In Switzerland 18 cases of humidifier syndrome were accepted by SUVA as occupational disease. 13 of the 18 cases occurred in the printing industry. In 13 out of 18 cases contaminated humidifiers were the cause of the syndrome and in five cases contaminated air-conditioning systems. Due to the often uncharacteristic clinical signs and symptoms and variable clinical features diagnosis of humidifier syndrome was missed by the general practitioner. Once humidifier fever was clearly diagnosed most workers had to change their working place. Despite the avoidance of exposure respiratory problems, radiographic changes and pulmonary function changes often persisted. Major pulmonary function decreases resulting in pulmonary invalidity were observed in five of the 18 cases (28%). Technical measures to prevent humidifier syndrome are described.