AIR-POLLUTANTS AND RESPIRATORY HYPERSENSITIVITY

Epidemiological evidence suggests that an increase in liquid petroleum derived pollutants is associated with exacerbation of allergic airway disease, and that the effects of pollution may occur 1-2 days later. Laboratory based studies have demonstrated that the pollutants respons ible for the adverse effects on respiratory health include nitrogen di oxide (NO2), sulphur dioxide (SO2), ozone (O-3) and respirable particu lates (PM(10)). More recently, studies of asthmatic individuals expose d to O-3, NO2 and a combination of NO2 and SO2 have indicated that the se agents increase the airway responsiveness of these individuals to i nhaled allergen, and that this effect may be maximal 24 h after exposu re to the pollutants. Studies investigating the putative mechanisms un derlying the effects of these pollutants suggest that exposure to thes e agents may lead to perturbation of the airway epithelium and release of pro-inflammatory mediators from the epithelial cells, which then i nfluence the activity of inflammatory cells, such as eosinophils.