In nonsmokers, lung cancer is a relatively rare disease with a long latent period. The time from diagnosis to death is often short, and treatment has limited success. To look at lung cancer in population-based studies, the population sample needs to be large and the follow-up time long. Therefore, despite the coherence between experimental information, occupational studies and many results in population studies, not all long-term epidemiological studies have shown a link between ambient air pollution and lung cancer mortality. In the ACS cohort study, lung cancer incidence increased by 8% per 10 μg·m-3 increase in PM2.5 levels, measured as between-city difference; in a Danish cohort study, lung cancer incidence increased by 3.7% per 10 μg·m-3 increase in NOx, used as a marker of exposure to traffic-related pollutants. Most importantly, particles – in particular those from diesel engines – are loaded with carcinogens. The Californian Enironmental Protection Agency as well as the International Agency for Research on Cancer list diesel exhaust as an established carcinogen.
The large-scale European Study of Cohorts for Air Pollution (ESCAPE) will add to the evidence of long-term effects of air pollution on chronic diseases, including a range of respiratory ailments, such as the incidence of asthma and COPD and the symptoms of bronchitis, as well as the development of lung function and lung cancer ( www.escapeproject.eu). Rigorous and standardised assessment of the exposure of European citizens to traffic-related pollution will highlight future policy requirements to tackle air quality along busy roads and highways.