Important deficits of lung function in three modern colliery populations. Relations with dust exposure

To determine whether dust-related "clinically important" deficits of lung function still occur in British coal miners we have analyzed the relationship between lifetime cumulative exposure to respirable dust and risk of defined functional deficits in a population of miners who were examined between 1981 and 1986. The study group consisted of a sample of men who had worked at any one of three collieries (South Wales, Yorkshire, and North East England) between 1970, when new dust standards were introduced, and date of medical survey. There were 1,671 men studied, including men who had left the collieries. "Clinically important" deficits of FEV1 from predicted values derived in this population were defined by comparisons with questionnaire data on exercise tolerance limited by breathlessness. The mean FEV1 of men in the South Wales colliery, for example, who said they had to stop for breath when walking at their own pace on level ground was 942 ml less than the predicted value for nonsmokers after taking age and stature into account. Individual cumulative exposures to respirable dust were calculated from a long-term program of measurements of dust concentrations and occupational records commencing in 1953. In the three colliery populations, 24, 24, and 12% in South Wales, Yorkshire, and the North East, respectively, had FEV1 deficits that were at least as severe as the average deficit associated with the severe grade of exertional dyspnea described above. In all collieries deficits were more common in smokers than in nonsmokers, and more common in men who had left the industry than in men still within it.(ABSTRACT TRUNCATED AT 250 WORDS)