Red blood cell antioxidants in human volunteers exposed to ozone.

Indices of red blood cell (RBC) antioxidant capacity can undergo changes upon exposure to oxidants, either acutely or chronically. To investigate whether these changes might provide a biochemical marker for acute environmental ozone exposure, we assessed RBC glutathione (GSH) and catalase (CAT) responses in seven normal volunteers exposed to 0.16 ppm ozone for 7.5 hours compared to the same measurements following sham exposure to clean air. For each subject, an interim period of two weeks separated the two exposure studies. Investigators performing the RBC assays were unaware of the environmental conditions. No changes in either GSH or CAT were observed for any study condition when compared to pre-study values. Our conclusion is that RBC antioxidants do not accurately reflect in vivo exposure to ozone at concentrations readily attainable during periods of heavy urban pollution. Our data dispute the value of these indices as markers of acute environmental photochemical oxidant exposure.