The potential of coal mine dust to cause disabling pneumoconiosis has long been recognised, but research now suggests that pneumoconiosis is not the only respiratory hazard of coal mining. Over the last 30 years evidence has accumulated that miners also experience an excess of chronic obstructive pulmonary disease (COPD), and this has led the British Government to classify chronic bronchitis and emphysema in coal miners as an occupational disease for which industrial injuries benefit can be paid. In Germany, too, COPD in miners is now compensated as an occupational disease. However, some scientists have expressed doubts as to whether coal mine dust can cause clinically important loss of lung function in the absence of complicated pneumoconiosis.1 In view of this continuing controversy, it is helpful to review the evidence as it now stands.

The epidemiological investigations that bear on the relation between coal mining and COPD are of four main types: (1) studies comparing lung function in miners and non-miners; (2) studies of the patterns of symptoms and lung function in miners according to their exposure to coal mine dust; (3) analyses of mortality from COPD in relation to coal mining; and (4) analyses of the relation between emphysema in coal miners at necropsy and their previous exposure to dust. In addition, investigations in the laboratory provide information about the toxicological mechanisms whereby coal mine dust might cause obstructive lung disease.