Abstract

The prevalence of respiratory symptoms and the smoking habits of 224 industrial `executives' aged 30 to 69 years in Social Classes I and II were ascertained by means of the Medical Research Council's questionnaire on respiratory symptoms; 31% had persistent cough, 25% had persistent phlegm, and 21% were short of breath on hurrying or going up a hill; 9% had had one or more chest illnesses in the past three years lasting for about a week, and 4% had `chronic bronchitis'—defined as persistent phlegm and one or more chest illnesses in the past three years; 67% were smokers, 21% smoking more than 25 cigarettes (or equivalent tobacco) per day; another 20% had stopped smoking. The prevalence of cough, phlegm, and breathlessness was closely related to smoking habit.

Data for those aged 40 to 59 years are compared with that obtained from London Transport Board workers and a sample of the population studied by the College of General Practitioners. The latter was further analysed and suggests that the prevalence of cough and phlegm is more closely related to the amount smoked than to social class. The prevalence of chest illness is probably more closely related to social class and less to the amount smoked. It is suggested that, although smoking may initiate irritative respiratory symptoms, the precursors of bronchitis, additional factors are important in causing progression to disabling or fatal chronic bronchitis.