Respiratory Disability in Coal Miners-Reply

In Reply.—  In response to Mr Elisburg, our sample may not have been representative, but our data are in accord with previous studies in working coal miners whose ventilatory capacity closely resembled that of the normal population, except when complicated CWP was present.¹ In regard to the role played by coal dust in the cause of COPD, while dust may lead to the development of industrial bronchitis and minor abnormalities of large-airways function, cigarette smoking is between six and ten times more important.² Moreover, industrial bronchitis does not lead to emphysema and is not peculiar to miners, but occurs in all dusty trades. Why, therefore, should miners be singled out for special attention? Nowhere has it been shown that the effects of coal dust and smoking are additive, and studies from the National Coal Board have shown that with increasing age and exposure, the contribution of dust to