[Effects of tropospheric ozone on human respiratory organs]

Ozone is a photochemical oxidant and by this property able to damage function and structure of respiratory epithelium resulting in diffuse inflammation of the respiratory tract. In physiopathological terms the reactions observed are similar to those of asthma by presenting an acute and reversible airway obstruction as well as a long lasting bronchial hyperresponsiveness. The harmful effects of ozone can occur in healthy subjects as well as in patients with preexisting bronchopulmonary diseases and are best correlated to the total inhaled dose of ozone. Therefore even moderate ozone concentrations inspired during vigorous exercise may have similar effects as high concentrations at rest. Although most of the acute effects of ozone on the respiratory tract are potentially reversible, there is however evidence of chronic health damage by repeated ozone exposure to populations in highly polluted areas. In conclusion it is nowadays accepted that acute exposure to ozone already at moderate concentrations can induce an acute asthmatic reaction in healthy human airways followed by a long lasting bronchial hyperresponsiveness. Thus, ozone has to be considered as a trigger in pathogenesis of asthmatic diseases, a hypothesis which seems to be supported by results of epidemiologic surveys.