Biomarkers of Dose and Effect of Inhaled Ozone in Resting versus Exercising Human Subjects: Comparison with Resting Rats

To determine the influence of exercise on pulmonary dose of inhaled pollutants, we compared biomarkers of inhaled ozone (O(3)) dose and toxic effect between exercise levels in humans, and between humans and rats. Resting human subjects were exposed to labeled O(3) ((18)O(3), 0.4 ppm, for 2 hours) and alveolar O(3) dose measured as the concentration of excess (18)O in cells and extracellular material of nasal, bronchial, and bronchoalveolar lavage fluid (BALF). We related O(3) dose to effects (changes in BALF protein, LDH, IL-6, and antioxidant substances) measurable in the BALF. A parallel study of resting subjects examined lung function (FEV(1)) changes following O(3). Subjects exposed while resting had (18)O concentrations in BALF cells that were 1/5th of those of exercising subjects and directly proportional to the amount of O(3) breathed during exposure. Quantitative measures of alveolar O(3) dose and toxicity that were observed previously in exercising subjects were greatly reduced or non-observable in O(3) exposed resting subjects. Resting rats and resting humans were found to have a similar alveolar O(3) dose.