Air pollution and asthma: molecular mechanisms.

Air pollution, in particular that generated by road traffic, is a matter of rising public concern and has been implicated in the worsening of asthma. In this article, the evidence that air pollutants (particularly sulphur dioxide, ozone and nitrogen dioxide) can affect the airways of asthmatic patients is reviewed, and the possible molecular mechanisms that may link air pollution to increased inflammation in the airways are discussed. Airway epithelial cells may respond to oxidant pollutants by the activation of transcription factors, such as nuclear factor kappa B, resulting in increased transcription of genes for certain cytokines, such as interleukin 8 and inflammatory enzymes, such as inducible nitric oxide synthase and cyclo-oxygenase.