An update on air pollution.

Air pollution is associated with adverse health effects. Much of the recent literature, which is the focus of this review, has concentrated on identifying individuals at risk and on the health effects of mixed pollutants. For indoor air, new analyses continue to support the notion that the risk of residential radon exposure is low and that environmental tobacco smoke may cause respiratory symptoms and dysfunction in adults, especially asthmatic adults, as well as in children. For outdoor air, the long-term effects of ozone exposure remain unclear, despite evidence of inflammation and small airway dysfunction after acute exposure. Ozone may increase the sensitivity of asthmatic patients to allergens. Increased morbidity in association with increasing particulate matter levels gives coherence to the argument that the relationship between particulate matter and mortality is causal. However, other investigators note the tight associations among outdoor pollutants and consider particulate matter a marker of air pollution levels.