Small airways dysfunction among non-smoking shipyard arc welders.

Increased volume of trapped gas (VTG), indicating small airways dysfunction, was found among 14 never smoking non-atopic welders who had worked for 10-31 (mean 22) years in their occupation. Spirometry and nitrogen wash out data were compared with those from a reference group of 14 never smoking men not exposed to welding. A methacholine provocation test was carried out. The effect was measured by change in forced expiratory volume in one second (FEV1) and VTG. The maximum decrease in FEV1 after inhalation of methacholine was 6% in welders and 2% among referents. Before provocation VTG and VTG total lung capacity (TLC) was higher among welders (127 ml v 98 ml and 1.76% v 1.38%). The increase in VTG and VTG/TLC was higher in welders after inhalation of methacholine at concentrations of 0.001% to 2% and remained increased after inhalation of salbutamol. The differences indicate small airways disease among shipyard welders.