Lung cancer and air pollution:: a 27 year follow up of 16 209 Norwegian men

Background: The well documented urban/rural difference in lung cancer incidence and the detection of known carcinogens in the atmosphere have produced the hypothesis that long term air pollution may have an effect on lung cancer. The association between incidence of lung cancer and long term air pollution exposure was investigated in a cohort of Oslo men followed from 1972/73 to 1998. Methods: Data from a follow up study on cardiovascular risk factors among 16 209 40 to 49 year old Oslo men in 1972/73 were linked to data from the Norwegian cancer register, the Norwegian death register, and estimates of average yearly air pollution levels at the participants' home address in 1974 to 1998. Survival analyses, including Cox proportional hazards regression, were used to estimate associations between exposure and the incidence of lung cancer. Results: During the follow up period, 418 men developed lung cancer. Controlling for age, smoking habits, and length of education, the adjusted risk ratio for developing lung cancer was 1.08 (95% confidence interval, 1.02 to 1.15) for a 10 mug/m(3) increase in average home address nitrogen oxide (NOx) exposure between 1974 and 1978. Corresponding figures for a 10 mug/m(3) increase in sulphur dioxide (SO2) were 1.01 (0.94 to 1.08). Conclusions: Urban air pollution may increase the risk of developing lung cancer.