Controlled exposure to combined particles and ozone decreases heart rate variability.

Abstract

This experiment was designed to test if controlled exposure to particles and ozone would result in decreased heart rate variability (HRV). Five asthmatic adults were exposed for 4 hours to; filtered-air, carbon and ammonium nitrate particles, and particles and ozone. Twenty-minute electrocardiograms were obtained before and after each exposure. Standard deviation of all normal-to-normal beat intervals (SDNN) decreased significantly across particles and ozone exposure compared with across filtered-air exposure (P = 0.01). Changes in SDNN-I (P = 0.04) and normalized low and high frequency (P = 0.02) were also seen across particles and ozone exposure; although these changes may best be characterized as trends given the small sample size. No significant changes in HRV were seen across the filtered-air or particles-only exposures. The results of this study suggest that combined particle and ozone exposure may decrease HRV in asthmatics. Further investigation is needed to confirm this finding.