ABSTRACT From a continuous series of 886 postmortem examinations on coal mine workers in New South Wales, Australia, from 1949 to 1982 and their histories the following data were obtained: age at death (886 cases), percentage of emphysema in both lungs (Heard method) (870 cases), bronchial gland wall (G-W) ratio (Reid Index) (412 cases), chest radiograph within 10 years of death (792 cases), history of work at the coal face (844 cases), history of amount of tobacco smoked (606 cases), and FEV1 five years before death (278 cases). Linear regression analysis showed the following: (1) The severity of emphysema had a significant positive regression on years of face work independently of age at death. (2) The severity of emphysema had a significant positive regression on the severity of ϰ-ray pneumoconiosis, which was best defined in the non-smoking group and the non-bronchitic group. (3) There was a significant multiple linear regression relationship between severity of emphysema (dependent variable) and pneumoconiosis and G-W (independent variables). The ratio of standardised regression coefficients was pneumoconiosis: G-W = 3:1. (4) The severity of ϰ-ray pneumoconiosis had a significant positive regression on years of face work and a negative regression on smoking amount. (5) G-W ratio had significant positive regression on age of death and severity of emphysema but not years of face work or severity of pneumoconiosis. (6) Smoking was not correlated with severity of emphysema or G-W ratio. (7) FEV1 (% predicted) was significantly negatively correlated with bronchitis, emphysema, and pneumoconiosis. (8) Severity of pneumoconiosis and emphysema have declined slightly but significantly over the 33 year period, but there has been no significant change in G-W ratio during 1960-82.
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