The effects of ozone exposure and associated injury mechanisms on the central nervous system

Ozone (O 3 ) is a component of photochemical smog, which is a major air pollutant and demonstrates properties that are harmful to health because of the toxic properties that are inherent to its powerful oxidizing capa- bilities. Environmental O 3 exposure is associated with many symptoms related to respiratory disorders, which include loss of lung function, exacerbation of asthma, airway damage, and lung inflammation. The effects of O 3 are not restricted to the respiratory system or func- tion - adverse effects within the central nervous system (CNS) such as decreased cognitive response, decrease in motor activity, headaches, disturbances in the sleep- wake cycle, neuronal dysfunctions, cell degeneration, and neurochemical alterations have also been described; furthermore, it has also been proposed that O 3 could have epigenetic effects. O 3 exposure induces the reactive chemical species in the lungs, but the short half-life of these chemical species has led some authors to attribute the injurious mechanisms observed within the lungs to inflammatory processes. However, the damage to the CNS induced by O 3 exposure is not well understood. In this review, the basic mechanisms of inflammation and activa- tion of the immune system by O 3 exposure are described and the potential mechanisms of damage, which include neuroinflammation and oxidative stress, and the signs and symptoms of disturbances within the CNS caused by environmental O 3 exposure are discussed.