Mortality and morbidity statistics suggest that miners and foundryworkers are more prone to bronchitis than other industrial workers but it is not yet certain that this excess is due to occupational factors. The present investigation was designed to compare the prevalence of bronchitis and respiratory disability in a representative sample of miners, foundryworkers, and other industrial groups living in Staveley, Derbyshire, a town of some 18,000 inhabitants, and to study some of the possible aetiological factors. A random sample of 776 men, stratified by age into two groups, 25 to 34 and 55 to 64 years, and by occupation into four groups, non-dusty, miners and ex-miners, foundry and ex-foundryworkers, and other dusty jobs, was used. Respiratory symptoms were recorded on a standardized questionnaire and the ventilatory capacity was assessed by means of the forced expiratory volume (F.E.V.0·75) and recorded as the indirect maximum breathing capacity (M.B.C.).
Miners and ex-miners recorded a higher prevalence of respiratory symptoms and a lower mean M.B.C. than men who had worked only in dust-free occupations. In the older age group the differences were not large and were not statistically significant but in the younger men the difference in the mean M.B.C. was significant. Foundry and ex-foundryworkers with a pure industrial history recorded a similar prevalence of symptoms to the men who had never worked in dusty occupations and their mean M.B.C. was only slightly and insignificantly lower. A higher prevalence of symptoms and a lower mean M.B.C. was, however, recorded by the foundrymen who had also been exposed to other dusts or fumes and the occupational histories suggested that such exposure was more likely than foundry work to account for the findings.
The number of years spent on the coal-getting shift was used to assess the importance of exposure to coal dust. In the elderly miners without pneumoconiosis there was a significant increase in the prevalence of breathlessness, accompanied by a reciprocal fall in the mean M.B.C. with increasing years spent on the coal-getting shift; but in no other group was a consistent trend found.
In both age groups the prevalence of respiratory symptoms was lower and the mean M.B.C. higher in non-smokers than in smokers and ex-smokers. Heavy smokers (those smoking 15g. and over/day) recorded a higher prevalence of symptoms and a lower mean M.B.C. than light smokers, and the values for ex-smokers approximated to those of the non-smokers.
The wives of the elderly men in the sample were studied to try to determine how far the apparently high rates of bronchitis shown by national mortality statistics are attributable to social factors. The findings suggested that the wives of the men who worked in dusty jobs had a somewhat higher prevalence of cough and/or sputum and of chest illness during the past three years than the wives of those who had worked only in dust-free occupations.