Oxidative damage to plasma constituents by ozone

The reaction of ozone (O 3 ) with human blood plasma was studied to help understand possible events that could occur in the respiratory tract. Uric acid (quantitatively the most important scavenger) and ascorbic acid were oxidized quickly, protein‐SH groups were lost more slowly, and there was no loss of bilirubin or α‐tocopherol. There was little formation of lipid hydroperoxides and no detectable formation of 4‐hydroxynonenal, hexanal or nonanal, or changes in lipoprotein electrophoretic mobility. Uric acid in human upper airway secretions may play a significant role in removing inhaled O 3 . Oxidative damage to lipids must not be assumed to be the key mechanism of respiratory tract O 3 toxicity.