EFFECT OF DUST SUPPRESSION MEASURES ON THE PREVALENCE OF COAL-WORKERS' PNEUMOCONIOSIS IN THE DUTCH COAL-MINES.

The underground workers in the Dutch coal-mines have been radiographed (70 mm.) seven times since 1949. The prevalence of coal-miners' pneumoconiosis shows a continuous decrease in all age groups. To evaluate the effect of the intensive system of dust suppression over this period a cohort analysis was made of the proportion of men with pneumoconiosis with the same number of years of exposure underground but who started work in different years. The results show that the number of men with pneumoconiosis decreases the longer they have worked in the period since dust suppression measures were applied intensively. The differences are significant at the 5% level.