Pulmonary and cardiovascular responses to repeated ozone exposure during exercise in adults with exercise-induced...

We tested the hypothesis that exercising while breathing real-world ozone (O₃) concentrations impairs pulmonary and cardiovascular function in individuals with exercise-induced bronchoconstriction (EIB) and that repeated exposures induce acclimation. Participants completed consecutive 30-min cycling sessions breathing room air (RA) and 170 ppb O₃. A mixed-effects model and ANOVA were used. Sixteen individuals (50% male) with mild-moderate EIB completed the study. O₃ exposure produced pulmonary impairment on Day 2 in forced expiratory volume in 1 s (Estimate = -5.1, 95% CI: -8.5 to -1.7, p = 0.003), forced vital capacity (Estimate = -4.0, 95% CI: -7.1 to -0.9, p = 0.008), and forced expiratory flow in the midportion of vital capacity (Estimate = -6.7, 95% CI: -12.7 to -0.7, p = 0.008). Minute ventilation was lower on Days 3 and 4 in O₃, p = 0.007 and p = 0.001. Diastolic blood pressure was lowest on Day 2 under O₃, 58 mmHg (95% CI: 52, 64) versus RA, 63 mmHg (95% CI: 58, 69), and a significant overall lower HR in O₃ was found across all visits, p = 0.032. These findings demonstrate a significant difference in pulmonary and cardiovascular responses to O₃ compared to RA, but no statistical evidence of acclimation.