title: Association between short term exposure to fine particulate matter and heart rate variability in older subjects with and without heart disease.
abstract: BACKGROUND
  Short term increases in exposure to particulate matter (PM) air pollution are associated with increased cardiovascular morbidity and mortality. The mechanism behind this effect is unclear, although changes in autonomic control have been observed. It was hypothesised that increases in fine PM measured at the subjects' home in the preceding hour would be associated with decreased high frequency heart rate variability (HF-HRV) in individuals with pre-existing cardiac disease.
  
  
  METHODS
  Two hundred and eighty five daily 20 minute measures of HRV (including a paced breathing protocol) were made in the homes of 34 elderly individuals with (n = 21) and without (n = 13) cardiovascular disease (CVD) over a 10 day period in Seattle between February 2000 and March 2002. Fine PM was continuously measured by nephelometry at the individuals' homes.
  
  
  RESULTS
  The median age of the study population was 77 years (range 57-87) and 44% were male. Models that adjusted for health status, relative humidity, temperature, mean heart rate, and medication use did not find a significant association between a 10 microg/m3 increase in 1 hour mean outdoor PM2.5 before the HRV measurement and a change in HF-HRV power in individuals with CVD (3% increase in median HF-HRV (95% CI -19 to 32)) or without CVD (5% decrease in median HF-HRV (95% CI -34 to 36)). Similarly, no association was evident using 4 hour and 24 hour mean outdoor PM2.5 exposures before the HRV measurement.
  
  
  CONCLUSIONS
  No association was found between increased residence levels of fine PM and frequency domain measures of HRV in elderly individuals.
authors.affiliation: Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, USA. sulljh@u.washington.edu
authors.forename: J H
authors.initials: JH
authors.lastname: Sullivan
authors.forename: A B
authors.initials: AB
authors.lastname: Schreuder
authors.forename: C A
authors.initials: CA
authors.lastname: Trenga
authors.forename: S L-J
authors.initials: SL
authors.lastname: Liu
authors.forename: T V
authors.initials: TV
authors.lastname: Larson
authors.forename: J Q
authors.initials: JQ
authors.lastname: Koenig
authors.forename: J D
authors.initials: JD
authors.lastname: Kaufman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000032:analysis / Q000633:toxicity*; D001145:Arrhythmias, Cardiac / Q000139:chemically induced / Q000503:physiopathology; D005260:Female; D006331:Heart Diseases / Q000150:complications* / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010316:Particle Size; D013997:Time Factors
chemical_list: D000393:Air Pollutants