Background Occupational exposures to vapours, gasses, dusts and fumes (VGDF) and chest X-ray abnormalities by the International Labour Office (ILO) classification system are associated with reduced lung function, with the majority of published studies being cross-sectional. We examined the effects of VGDF exposures, as well as ILO parenchymal changes, pleural plaque and diffuse pleural thickening (DPT) on reduction in lung function in a longitudinal study.

Methods Chest radiographs and spirometry for 3150 ageing construction workers enrolled in a medical screening programme with a baseline and at least one follow-up examination were studied. Indices for VGDF exposure, parenchymal changes, pleural plaque and DPT severity were developed and used in longitudinal mixed models of lung function.

Results Smoking and VGDF exposure were associated with decreased FEV₁ and FVC at baseline as well as accelerated rates of annual decline. High VGDF exposure was associated with a yearly decline of −19.5 mL for FEV₁ and −15.7 mL for FVC. Parenchymal abnormalities, pleural plaque and DPT were more strongly associated with reduced FVC. An increase of one unit in the pleural plaque severity index resulted in approximately −5.3 mL loss of FVC and −3.3 mL loss of FEV_1, with a possible non-linear effect of plaque on FEV₁.

Conclusions Increasing pleural plaque severity was associated with progressively greater loss of FVC and FEV₁, supporting a causal association. VGDF exposures were associated with reduced FVC and FEV₁ at baseline as well as accelerated annual loss of lung function.