Objectives To investigate the relationship between dust exposure and annual change in lung function among employees in Norwegian silicon carbide (SiC) plants using a quantitative job exposure matrix (JEM) regarding total dust.

Methods All employees, 20–55 years of age by inclusion (n=456), were examined annually for up to 5 years (1499 examinations). Spirometry was performed at each examination, and a questionnaire encompassing questions of respiratory symptoms, smoking status, job and smoking history, and present job held was completed. A JEM was constructed based on 1970 personal total dust exposure measurements collected during the study period. The association between lung function and total dust exposure was investigated using linear mixed models.

Results The annual change in forced expiratory volume (FEV) in one second per squared height, FEV₁/height², per mg/m³ increase in dust exposure was −2.3 (95% CI −3.8 to −0.79) (mL/m²)×year⁻¹. In an employee of average height (1.79 m) and exposure (1.4 mg/m³) the estimated contribution to the annual change in FEV₁ associated with dust was 10.4 mL/year. The annual change in FEV₁/height² in current, compared with non-smokers was −1.9 (−7.2 to 3.4) (mL/m²)×year⁻¹. The estimated overall annual decline in FEV₁ among current and non-smokers in the highest exposed group was −91.2 (−124.3 to −58.1) (mL/m²)×year⁻¹ and −49.0 (−80.2 to −17.8) (mL/m²)×year⁻¹, respectively.

Conclusions Dust exposure, expressed by a quantitative JEM, was found to be associated with an increased yearly decline in FEV₁ in employees of Norwegian SiC plants.