Increased decline in pulmonary function among employees in Norwegian smelters reporting work-related asthma-like symptoms

Objective: To investigate associations between work-related asthma-like symptoms (WASTH) and annual pulmonary function decline among employees of 18 Norwegian smelters. Methods: A 5-year longitudinal study in which WASTH was defined as a combination of dyspnea and wheezing that improved on rest days and vacation. Results: A total of 12,966 spirometry examinations were performed in 3084 employees. Crude annual decline in forced expiratory volume in 1 second (FEV1) (dFEV1) was 32.9 mL/yr (95% confidence interval, 30.5 to 35.3), and crude annual decline in forced vital capacity (FVC) (dFVC) was 40.9 mL/yr (37.8 to 43.9). After adjustment for relevant covariates, employees reporting WASTH showed higher dFEV1 by 16.0 m:/yr (3.4 to 28.6) and higher dFVC by 20.5 mL/yr (6.0 to 35.0) compared with employees not reporting WASTH. Conclusion: Work-related asthma-like symptom was associated with greater annual declines in FEV1 and FVC, indicating a restrictive pattern.