Urban air pollution and lung cancer in Stockholm

We conducted a population based case-control study among men 40-75 years of age encompassing all cases of lung cancer 1985-1990 among stable residents of Stockholm County 1950-1990. Questionnaires to subjects or next-of-kin ( primarily wives or children) elicited information regarding smoking and oth er risk factors, including occupational and residential histories. A high r esponse rate (>85%) resulted in 1,042 cases and 2,364 controls. We created retrospective emission databases for NOx/NO2 and SO2 as indicators of air p ollution from road traffic and heating, respectively. We estimated local an nual source-specific air pollution levels using validated dispersion models and we linked these levels to residential addresses using Geographical inf ormation System (GIS) techniques. Average traffic-related NO2 exposure over 30 years was associated with a relative risk (RR) of 1.2 (95% confidence i nterval 0.8-1.6) for the top decile of exposure, adjusted for tobacco smoki ng, socioeconomic status, residential radon, and occupational exposures. Th e data suggested a considerable latency period; the RR for the top decile o f average traffic-related NO2 exposure 20 years previously was 1.4 (1.0-2.0 ). Little association was observed for SO2. Occupational exposure to asbest os, diesel exhaust, and other combustion products also increased the risk o f lung cancer. Our results indicate that urban air pollution increases lung cancer risk and that Vehicle emissions may be particularly important.