Interaction of smoking and urban air pollution in the etiology of lung cancer.

Surveillance of lung cancer incidence based on mortality was carried out over 6 years in Cracow. It appeared that lung cancer death rates among Cracow inhabitants were higher than average rate in the population of Poland but this difference in the large extent could be explained by the greater prevalence of smoking habit in Cracow than in whole Poland. Very intriguing was a substantial excess of lung cancer deaths only in male residents of the city center having the highest level of the air pollution. Since this excess in the lung cancer deaths could not be exclusively explained by smoking or occupational hazards the air pollution should be assumed as a responsible factor. Lack of the similar phenomenon in females living in the city center can be explained by the fact that the air pollution alone is not sufficient cause in the etiology of lung cancer but that in combination with other adverse factors like smoking or occupational hazards it develops its carcinogenic effect.