Objectives To determine the autonomic cardiovascular control among residents of Hawaii who are exposed to varying levels of volcanic air pollution (vog), which consists largely of sulfur dioxide (SO2) and acid aerosols.
Methods In a cross-sectional study between April 2006 and June 2008, the authors measured cardiovagal autonomic function by heart-rate variability (HRV) in 72 healthy individuals who lived in four exposure zones on Hawaii Island: vog-free (n=18); episodic exposure to SO2 >200 ppb and acid aerosol (n=19); chronic exposure to SO2 ≥30 ppb and acid aerosol (n=15); and chronic exposure to acid aerosols (n=20). Individuals with diabetes or heart disease, or who had smoked in the preceding month were excluded. HRV was measured in all subjects during rest, paced breathing and active standing (Ewing manoeuvre). HRV was analysed in time and frequency domains and compared between the four exposure zones.
Results There were no significant differences between exposure zones in HRV, in either time or frequency domains, even after adjustment for age, gender, ethnicity and body mass index. There was no significant HRV change in three individuals in whom HRV was measured before and during an exposure to combined SO2 100–250 ppb and concentration of respirable particles of diameter ≤2.5 μ (PM2.5) >500 μg/m3. Age was significantly correlated with time-domain parameters during paced breathing and the Ewing manoeuvre.
Conclusions This study of healthy individuals found no appreciable effects of vog on the autonomic nervous system.
- heart rate variability
- autonomic nervous system
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Funding This investigation was supported by the United States Centers for Disease Control (CDC) grant 1R01 EH000111; Hawaii State Department of Health; American Lung Association of Hawaii; Leahi Fund, Hawaii Community Foundation. DCC is recipient of NIH grant K23 HL088981 and funding from NCRR 1 R25 RR019321. This manuscript is solely the responsibility of the authors and does not necessarily represent the official views of the NIH, CDC, Hawaii State Department of Health, American Lung Association of Hawaii, or Hawaii Community Foundation. The JMP statistical software licence was supported by NIH Grant number RR-16467 from the HS-BRIN programme of the National Center for Research Resources.
Competing interests None.
Ethics approval Ethics approval was provided by the University of Hawaii Committee on Human Studies.
Provenance and peer review Not commissioned; externally peer reviewed.
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