Occupational lung diseases are caused or made worse by exposure to harmful substances in the work-place. "Pneumoconiosis" is the term used for the diseases associated with inhalation of mineral dusts. While many of these broad-spectrum substances may be encountered in the general environment, many occur in the work-place for greater amounts as a result of industrial processes; therefore, a range of lung reactions may occur as a result of work-place exposure. Physicians in metropolitan cities are likely to encounter pneumoconiosis for two reasons: (i) patients coming to seek medical help from geographic areas where pneumoconiosis is common, and (ii) pneumoconiosis caused by unregulated small-scale industries that are housed in poorly ventilated sheds within the city. A sound knowledge about the various pneumoconioses and a high index of suspicion are necessary in order to make a diagnosis. Identifying the disease is important not only for treatment of the individual case but also to recognise and prevent similar disease in co-workers.