This article is a commentary on the following study: Schikowski T, Sugiri D, Ranft U, Gehring U, Heinrich J, Wichmann HE, Kramer U. Long-term air pollution exposure and living close to busy roads are associated with COPD in women. Respir Res. 2005 Dec 22;6:152. The objective of this study is to investigate the association between, on the one hand, long-term exposure to traffic-related air pollution and, on the other hand, respiratory symptoms and lung function (and more specifically chronic obstructive pulmonary disease, or COPD, as defined by lung function measurements) in women aged 55 years. This study has the advantage of a large sample size, which gives it good statistical power. Furthermore, the measurement of individual exposure using GIS data lends it objectivity. The same applies to the definition of COPD, which is based on respiratory parameters rather than solely on symptoms reported in a questionnaire. (Excerpts from the article)