Dust Exposure Assessed by a Job Exposure Matrix Is Associated with Increased Annual Decline in FEV1 A 5-year Prospective Study of Employees in Norwegian Smelters

Rationale: The relationship between dust exposure and annual decline in lung function among employees in the smelting industry is unknown. Objectives: The aim of the study was to investigate the relationship between annual change in lung function and occupational dust exposure among workers in 15 Norwegian smelters. Methods: All employees (n = 2,620) were examined annually for 5 years (11,335 health examinations). At each examination spirometry was performed and a respiratory questionnaire was completed. The smelters were grouped as follows: (1) ferrosilicon alloys (FeSi) and silicon metal (Si-metal); and (2) silicon manganese (SiMn), ferromanganese (FeMn), and ferrochromium (FeCr). A job exposure matrix was available on the basis of 2,619 personal dust exposure measurements. The association between lung function expressed as FEV1 and FVC per squared height (height2) and dust exposure was investigated using multivariate linear mixed model analyses. Measurements and Main Results: The annual change in FEV1/height2 (δFEV1) related to dust exposure in the FeSi/Si-metal and SiMn/FeMn/FeCr smelters was –0.42 (95% confidence interval, −0.95 to 0.11) and −1.1 (−2.1 to −0.12) (ml/m2) × (mg/m3)−1 × year−1, respectively. The annual decline in FEV1/height2 was 1.6 ml/m2 (0.15 to 3.1) steeper in smokers than in nonsmokers. The median geometric mean of the...