Lung function of workers exposed to antigens from a contaminated air-conditioning system

Following the manifestation of humidifier fever in a number of workers in a carpet yarn texturing plant, a comparative study was begun of a group of workers exposed to fungi from the air-conditioning system and a control group not so exposed. For both group of workers anamnestic data were collected, intracutaneous skin tests were performed, certain lung function parameters were determined, and the presence of antibodies to a number of antigens from the system was tested for. It was found that the group of exposed workers had a significantly higher rate of positive intracutaneous skin test than non-exposed workers. Additionally, their serology was more often positive. Both positive skin test and positive serology were more frequent in non-smokers than in smokers. A positive immediate skin reaction among exposed workers was found to correlate with an FEF25–75 reduction during the working week. A positive delayed skin reaction among exposed workers correlated with a lower FVC prior to the start of the working week than recorded for non-exposed workers. A positive serology in exposed workers did not correlate with a difference in lung function compared with non-exposed workers, nor was there a correlation with a change in lung function in the course of the working week. When humidifier fever is diagnosed, steps should be taken to reduce exposure. It would also appear desirable to keep exposed workers under medical observation and to monitor the subsequent development of their lung function.