[A follow-up study on pulmonary functions of workers exposed to various forms of dust. Observation on the workers of pneumoconiosis in Kitakyushu].

Serial spirograms of 121 dust workers whose chest X-rays were found to be "class 1" of the diagnostic criteria for pneumoconiosis were obtained during 1978-80. Yearly changes of pulmonary function variables (%VC, FEV1, FEV1/FVC%,V25/H, and V50/V25) by age, smoking habit, total years of exposure to dust, and work history were evaluated. The average age of the dust workers was 48.0 +/- 5.5 years, and the average years of exposure to dust was 21.6 +/- 6.8 years in 1978. Eighty-two dust workers smoked with the mean smoking history of 24.7 pack-years. No significant differences of spirograms were found between the smoking and non-smoking groups. Among the smokers, however, linear regression of FEV1/FVC% by age gradually decreased during 1978-80. All the pulmonary function variables showed no correlation with smoking history as well as total years of dust exposure. All the dust workers were classified into eight types of work by their histories; crushing and quarrying operators, brick mason, foundry and grinding operators, asbestos workers, underground miners, refractory material workers, pyrites roasters, and welders. The underground miners showed lower FEV1/FVC% and V25 than the average. However, the difference of such pulmonary function variables by eight types of work was not significant by analysis of variance. Since aging is the most dominant factor for pulmonary dysfunction, a longer observation on this group will be needed.