The nose may help protect the lower respiratory tract from the effects of ambient ozone by scrubbing ozone from inspired air. Reductions in both nasal resistance and nitric oxide production with exercise may influence the efficiency of ozone uptake in the nose. Nasal ozone uptake was measured in ten healthy volunteers before and after 15 minutes of moderate, bicycle exercise. Ozone (0.2ppm) was pulled through both nostrils and out of the mouth at a constant flow while the subject closed their epiglottis. Nasal uptake of ozone was determined by comparing the ozone concentration entering the nostrils to that exiting the mouth. Average pre-exercise uptake of ozone was 56% (± 7.8) and 37% (± 4.9) at 10 and 20 L/min, respectively. These averages did not significantly differ from those immediately post-exercise (55% and 37%). Nasal ozone uptake increased significantly (p < 0.001) with decreasing flow rate, but intersubject variability in uptake could not be predicted by nasal volume or cross-sectional areas (as measured by acoustic rhinometry), or endogenous nitric oxide production. However, the percent change in ozone uptake after exercise, within an individual, was correlated with both 1) percent change in nasal volume (r = 0.70 at 10 L/min) and 2) percent change in the rate of volumetric expansion between the nasal valve and turbinates (r = 0.82 at 10 L/min). These results may be useful for assessing human risk associated with ozone exposure during exercise.