The association between personal measurements of environmental exposure to particulates and heart rate variability.
BACKGROUND
Epidemiologic evidence indicates that airborne particulates are associated with mortality risk, predominately from heart disease. This may occur through changes in the cardiac autonomic nervous system, witnessed by changes in heart rate variability.


METHODS
This short-term longitudinal study used continuous personal particulate matter measurements to examine the effects of exposure to particulate matter less than 2.5 microm in diameter (PM2.5) on heart rate and rate variability in 20 relatively young, healthy male workers. Continuous exposure and cardiac monitoring were performed on each subject on a nonwork day. The 5-minute standard deviation of the normal-to-normal interval was used as the main measure of heart rate variability.


RESULTS
Mixed-effects regression models estimate an average 1.4% (95% confidence limits = -2.1, -0.6) decrease in the 5-minute standard deviation of the normal-to-normal interval for each 100 microg/m3 increase in the 3-hour PM2.5 moving average, and small increases in heart rate, after adjustment for potential confounding factors. Predicted effects of exposure were greatest using the 3-hour averaging interval for PM2.5 and decreased in magnitude using shorter and longer intervals.


CONCLUSIONS
These results reveal an association between cardiac autonomic function and environmental PM2.5 exposure. These observed associations may result from decreased vagal or increased sympathetic tone.
Magari
Shannon R
SR
Occupational Health Program, Harvard School of Public Health, Boston, MA 02115, USA.
Schwartz
Joel
J
Williams
Paige L
PL
Hauser
Russ
R
Smith
Thomas J
TJ
Christiani
David C
DC
D000328:Adult; D000393:Air Pollutants / Q000009:adverse effects*; D001341:Autonomic Nervous System / Q000502:physiology*; D015716:Electrocardiography, Ambulatory; D004781:Environmental Exposure / Q000009:adverse effects*; D006331:Heart Diseases / Q000209:etiology / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects*; D010316:Particle Size; D012044:Regression Analysis
D000393:Air Pollutants