Factors affecting FEV1 in workers with potroom asthma after their removal from exposure.

OBJECTIVE

In this study the relationship has been studied between exposure time and potential prognostic factors and FEV1 percent predicted (FEV1-% pred) in workers with potroom asthma, after their transfer from exposure to exposure-free departments.

METHODS

Between 1970 and 1990 in a Dutch aluminium-production plant, 179 workers had been diagnosed as having potroom asthma. We carried out a follow-up study (n = 122) in the population still present at the factory 5 years after their relocation to an exposure-free department. In this study population, we examined the relationship between FEV1-% pred at follow-up, and exposure time: the time interval between start of exposure and diagnosis. To correct for confounding factors, we included age, pre-employment FEV1-% pred, allergy, medical treatment, and smoking in the analysis.

RESULTS

The mean FEV1-% pred at follow-up was within the normal range (90.3, SD 13.5). Long exposure time was significantly associated with a low FEV1-% pred at follow-up (P = 0.0046). Adjustment was necessary for pre-employment FEV1-% pred and current smoking as confounding factors.

CONCLUSION

Long duration of exposure is a factor affecting FEV1 in workers with potroom asthma. The results of this study give support for additional preventive measures to be taken, such as early recognition of work-related respiratory complaints and repeated education.