Abstract

The aim of the study was to analyse the effects of smoking, in particular to show its causal role in the development of airflow obstruction, and to look at changes in smoking habits. The study was conducted among 556 men, aged 30 to 54 in 1960, surveyed twice, in 1960 and 1972. The hypothesis of tobacco as a causal factor of airflow obstruction is strengthened, following this study, by three results: 1) FEV1 slope was related to tobacco consumption, even after adjustement for FEV1 level (42 ml/yrs for non-smokers, 51 ml/yrs for heavy smokers); 2) FEV1 loss with age increased with the amount of tobacco consumption: one pack a day smoked for 25 years was equivalent to an aging of 5 years; 3) FEV1 loss decelerated if the subject gave up smoking, thus preventing any further risk. What appeared to be a spontaneous regulation in smoking habits was observed. The men who stopped smoking were those with low respiratory status. In this population, men who were ex-smokers in 1960 and maintained this status until 1972 had a FEV1 slope similar to that of the non-smokers

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