Adolescent asthmatic subjects have been shown to be much more sensitive than healthy adolescents to the inhaled effects of sulfur dioxide. To test whether similar adolescent asthmatics are more sensitive to other common ambient air pollutants, 10 healthy and 10 asthmatic adolescent subjects were exposed for 60 min to filtered air, 0.12 ppm ozone (O3), and 0.12 ppm nitrogen dioxide (NO2) on separate days at rest. The following pulmonary functional values were measured before, at 30 min, and after 60 min of exposure: peak flow, total pulmonary resistance (RT), thoracic gas volume at functional residual capacity (FRC), maximal flow at 50 and 75% of expired vital capacity (Vmax50 and Vmax75), and forced expiratory volume in one second (FEV1). Following 60 min of exposure at rest to low concentrations of O3 or NO2, there were no consistent significant functional changes in either healthy or asthmatic adolescent subjects. There also were no measurable differences between the 2 groups.