Traffic related pollution and heart rate variability in a panel of elderly subjects

Abstract

Background: Particulate air pollution has been associated with increased cardiovascular deaths and hospital admissions. To help understand the mechanisms, the types of particles most involved, and the types of persons most susceptible, the association between exposure to summertime air pollution and heart rate variability (HRV) was examined in a panel study of 28 elderly subjects. Methods: Subjects were seen once a week for up to 12 weeks and HRV (SDNN, r-MSSD, PNN 50 , low frequency/high frequency ratio (LFHFR)) was measured for approximately 30 minutes at each session using a defined protocol. Temperature, day of the week, and hour of the day were controlled, and dummy variables for each subject were controlled for subject specific risk factors. Results: PM 2.5 was associated with r-MSSD (210.1% change for an interquartile range (IQR) increase in exposure (95% CI 22.8 to 216.9)) and PNN 50 , but stronger associations were seen with black carbon, an indicator of traffic particles, which was also associated with SDNN (24.6% per IQR (95% CI 22.0 to 27.2)) and LFHFR. Secondary particles were more weakly associated with r-MSSD, as was ozone. No associations were seen with SO 2 or NO 2 . CO had similar patterns of association to black carbon, which disappeared after controlling for black carbon. Black carbon had a substantially higher effect on SDNN in subjects who had had a previous myocardial infarction (212.7%, 95% CI 25.7 to 219.25). Conclusions: Particles, especially from traffic, are associated with disturbances of autonomic control of the heart.

Source location of air pollution and cardiac autonomic function: Trajectory cluster analysis for exposure assessment

“…In a recent population-based study, O'Neill et al (2005) also found independent effects of sulfate and BC on depressed vascular reactivity among patients with diabetes. Moreover, Schwartz et al (2005) reported that BC was more strongly associated with decreased HRV than were other particle components.…”

“…These physiologic effects may vary according to the physical and chemical characteristics of the pollutants. Previous studies have evaluated whether certain components of airborne particles, such as transition metal elements, black carbon (BC), and/or sulfate (SO 4 2À ) are responsible for health effects observed in epidemiologic research (Godleski et al, 2000;Laden et al, 2000;Magari et al, 2002;O'Neill et al, 2005;Schwartz et al, 2005). A panel study performed in Boston observed a significant association between BC, a marker of traffic particles, and decreased heart rate (HR) variability (HRV), a marker of cardiac autonomic dysfunction .…”

Is Ambient PM 2.5 Sulfate Harmful?

“…Schwartz et al (2005) found consistent associations for measures of heart rate variability with BC, but fewer associations for PM 2.5 . In that study, the authors used an algorithm separating BC from PM 2.5 and found no associations with the PM 2.5 remainder (termed “secondary PM 2.5 ” by the authors), which would include both secondary sulfate and its reaction products.…”

Characterizing Urban Traffic Exposures Using Transportation Planning Tools: An Illustrated Methodology for Health Researchers

“…40 Several studies indicate that older (65+) adults are at greater risk of the adverse effects of traffic exposures. 21,41,42 Traffic density analyses provide a comprehensive and multi-directional assessment of airborne environmental burdens from roads within a certain radius of a residence. 5 In urban areas, roadway grids can be closer than 200 m, producing additive traffic-related effects that depend on the density of the road network.…”