A survey of the respiratory health of silica-exposed gemstone workers in Hong Kong.

Respiratory symptoms and radiographic and lung function alterations were studied in a cross-sectional survey of gemstone workers in Hong Kong. The study population included a group of grinders, polishers, and buffers who were heavily exposed to dust (principally free silica) and a less exposed group of cutters and carvers. Among all 218 male workers who answered the respiratory questionnaire, heavily exposed workers reported significantly higher prevalence of respiratory symptoms suggestive of mucus hypersecretion. Radiological pneumoconiosis defined as opacities with profusion of 1/0 and above was found in 27% of 157 workers who accepted radiographic and lung function examination. Radiological opacities were significantly related to increasing years of employment in both groups of workers after taking into account age and smoking habits. Decline in forced vital capacity (FVC) was significantly related to increasing years of employment in both groups after allowing for the effects of age, height, and smoking. A modest decline in forced expiratory volume in one second (FEV1) was related to dust exposure which was of borderline statistical significance in polishers and buffers who smoked. Radiological pneumoconiosis did not have an independent effect on lung function when allowance was made for dust exposure.