Ground-level ozone is a pollutant that has been found to have detrimental effects on plants as well as in humans. Few studies, however, have measured ozone exposure in mountainous regions downwind from highly polluted urban centers, despite the popularity of these regions as summer destinations. The study reported here evaluated ozone levels in Fresno, California, and the downwind community of Shaver Lake, California, during the summer months of June, July, and August from 1997 to 2001. Findings from the study suggest that if Fresno is considered one of the most polluted cities in the nation, then Shaver Lake should be considered one of the most polluted rural sites. Continuing and expanded monitoring of surface ozone concentrations at remote and rural locations is needed, because it is important to assess the risk for humans, animals, and plants.