Ambient air pollution and the lungs: what do clinicians need to know?

Ozone, oxides of nitrogen, sulphur dioxide and particulate matter are the important ambient air pollutants associated with adverse health effects. A large number of ambient air pollutants have been isolated from the fetal cord blood indicating that babies are exposed to air pollutants even before they are born. Children and the elderly are most susceptible to the harmful effects of ambient air pollutants. High levels of ambient air pollutants are associated with increased incidence or worsening of asthma and increased risk of developing allergic diseases, respiratory symptoms and respiratory tract infections. Mortality rates also increase in individuals with pre-existing cardiorespiratory diseases. The underlying mechanism for the harmful effects is the generation of oxidative stress which induces a strong respiratory as well as systemic inflammatory response. Individuals with genetic defects in enzymes associated with antioxidant defences seem to be particularly vulnerable to the harmful effects of air pollutants. Supplementation with antioxidants such as N-acetyl cysteine and sulforaphene has shown some protective effects in preliminary studies. High doses of vitamin C and vitamin E have shown some benefit in genetically susceptible asthmatic children. Physicians should play an important role in advocating to governments for a reduction in ambient air pollutants using innovative strategies and stricter legislation. Clearly more research is required to better understand intervention strategies to reduce morbidity and mortality due to ambient air pollutants, but in the meantime, the least we can do is to supplement diets with rich sources of antioxidants.