The effect of CAPs with and without O
on heart rate and heart rate variability. All animals were placed in the chambers and allowed to acclimate for 1 hr before the exposure began (Baseline) and then exposed for 4 hrs (shaded area). When compared to pre-exposure, all animals experienced an increase in HR during baseline, and then a progressive decrease from baseline during hour-1, 2, 3 and 4 of exposure (Exp1, Exp2, Exp3, and Exp4). Exposure to UFCAPs with (UF/O3) or without (UF) ozone did not cause any significant changes in HR or HRV at any time point (Column A.). Similarly, there was no effect of FCAPs alone (F) on any parameter; only exposure to FCAPs + O3 (F/O3) significantly decreased SDNN when compared to FA (Column B.). Exposure to ozone alone did not cause any significant effects (Column C.). Bracket indicates that each hour of the exposure period is significantly different. Values are mean ± SEM; *p < 0.05, significantly different from FA (n = 6).