Research during the past 10–20 years confirms that
outdoor air pollution contributes to morbidity and
mortality.1,2 Whereas some effects may be related to
short-term exposure,3 others have to be considered
contributions of long-term exposure.4,5 Although the
mechanisms are not fully explained, epidemiological
evidence suggests that outdoor air pollution is a
contributing cause of morbidity and mortality.6 State-ofthe-art
epidemiological research has found consistent
and coherent associations between air pollution and
various outcomes (eg, respiratory symptoms, reduced
lung function, chronic bronchitis, and mortality).6