Background: Asthma is a chronic airway inflammatory disease with episodic symptoms of wheezing, chest tightness, cough, and shortness of breath. High ambient ozone levels have been associated with increased airway inflammation and asthma morbidity in prior studies. Mechanisms underlying individual susceptibility to asthma exacerbations from poor air quality are not fully understood. Objective: As part of a panel observational study, we hypothesized that systemic antioxidant ability and antioxidant status may be associated with more stable asthma during high ozone season. Methods: A cross sectional study was performed to evaluate the antioxidant profile in systemic circulation and its associations with clinical parameters in asthmatics and healthy controls during three summers in Atlanta, Georgia. Results: In this panel of individuals with and without asthma, we found that although systemic glutathione levels were not different between the groups, serum albumin was significantly lower in the asthmatic group. Albumin also significantly correlated with lung function (%FEV 1 ) and asthma quality of life scores. In a subgroup tested, plasma reduced glutathione (GSH) levels were associated with worse airways obstruction. Conclusion: Antioxidants GSH and albumin may have a role in maintaining lung function and asthma stability during times of poor ambient air quality. Clin Trans Sci 2014; Volume 7: 314-318