A group of 1404 middle-aged men from Aalborg who were examined in 1974 with interview and lung function tests were re-examined in 1985 using a postal questionnaire. Of the 1404 men, 1045 could be classified into well-defined occupational categories using information up to 1974. Of these men, 791 were alive at the time of the questionnaire survey. Questions on lung symptoms, occupation and smoki...