[Lung cancer, tobacco smoking and environmental factors in Denmark]

In the 1980's the incidence of lung cancer in Copenhagen was nearly twice that of the incidence in the rural areas. A 17 year follow up study of all economically active persons aged 30-64 in Denmark at the census in 1970, supplied with smoking information on a group level from marketing surveys 1970-72, shows that differences in smoking habits was the main factor behind the regional differences in lung cancer. Differences in smoking habits explained about 60% of the excess lung cancer risk for men in Copenhagen and about 90% for women. Occupational risk factors also seemed to have an important role. After control for smoking, workers had twice the lung cancer risk of teachers and academics. There was only a small independent effect of geographical region, which suggests that an influence of outdoor air pollution on lung cancer risk is identifiable only for air pollution levels above that of Copenhagen around 1970.