Particulate matter and heart rate variability among elderly retirees: the Baltimore 1998 PM study

Abstract

This study investigates the relationship between ambient fine particle pollution and impaired cardiac autonomic control in the elderly. Heart rate variability ( HRV ) among 56 elderly ( mean age 82 ) nonsmoking residents of a retirement center in Baltimore County, Maryland, was monitored for 4 weeks, from July 27 through August 22, 1998. The weather was seasonally mild ( 63 ± 848F mean daily temperature ) with low to moderate levels of fine particles ( PM 2.5 < 50 g / m 3 ) . Two groups of approximately 30 subjects were examined on alternate days. A spline mixed -effects model revealed a negative relationship between outdoor 24 -h average fine particulate matter ( PM 2.5 ) and high -frequency ( HF ) HRV that was consistent with our earlier Baltimore study for all but 2 days. These 2 days were the only days with significant precipitation in combination with elevated PM 2.5 . They were also unusual in that back -trajectory of their air masses was distinctly different from those on the other study days, emanating from the direction of rural Pennsylvania. Mixed -effects analysis for all 24 study days showed a small negative association of outdoor PM 2.5 with HF HRV ( À 0.03 change in log [ HF HRV ] for a 10 g / m 3 increment in PM 2.5 ) after adjustment for age, sex, cardiovascular status, trend, maximum temperature, average dew point temperature, random subject intercepts, and autocorrelated residuals. After excluding study days 4 and 5, this association was strengthened ( À 0.07 change in log [ HF HRV ] for 10 g / m 3 PM 2.5 , 95% CI À 0.13 to À 0.02 ) and was similar to that obtained in an earlier study ( À 0.12 change in log [ HF HRV ] for a 10 g / m 3 increment in outdoor PM 2.5 , 95% CI À 0.24 to À 0.00 ) [ Liao D., Cai J., Rosamond W.D., Barnes R.W., Hutchinson R.G., Whitsel E.A., Rautaharju P., and Heiss G. Cardiac autonomic function and incident coronary heart disease: a population -based case -cohort study. The ARIC Study. Atherosclerosis Risk in Communities Study. Am J Epidemiol 1997: 145 ( 8 ) : 696 ± 706 ] . Acute ( 1 to 4 h ) previous PM 2.5 exposure did not have a stronger impact than the 24 -h measure. A distributed lag model incorporating the six preceding 4 -h means also did not indicate any effect greater than that observed in the 24 -h measure. This study is consistent with earlier findings that exposures to PM 2.5 are associated with decreased HRV in the elderly.

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

“…They found significant increases in the standard deviation (SD) of HR and parasympathetic function and a significant decrease in average HR on days on which the air came from the northwest versus other directions. The association of air pollution and HRV among elderly individuals in Baltimore varied depending on the direction of air-mass trajectories for certain days (Creason et al, 2001). These findings and other evidence support the notion that air-mass origin can modify the effects of air pollution, and may also serve as a surrogate for complex mixtures from the sources in that location.…”

Bayesian hierarchical modeling of cardiac response to particulate matter exposure

“…Complete details of the design, materials and methods are given in the studies by Williams et al (2000a, b) and Creason et al (2001). The study was conducted at an 18-story retirement facility in central Baltimore county (Towson, MD, USA), B15 km from downtown Baltimore, over a 4-week period from 26 July to 21 August 1998.…”

“…Briefly, HRV measures were taken over a period of 1 month for 56 respondents, 21 of whom wore personal PM 2.5 exposure monitors. Creason et al (2001) reported a small negative association between HRV and outdoor PM 2.5 on the previous day after adjusting for age, sex and cardiovascular status in mixed effects models. Findings based on PM 2.5 concentrations at a central indoor site were similar.…”

“…In this study, we expand on the studies by Liao et al (1999) and Creason et al (2001) to include personal PM 2.5 measurements, and we develop our models in a Bayesian hierarchical framework, which integrates data obtained from personal, indoor and outdoor monitoring and meteorological data. We develop a sequence of nested probability models that integrate different types of data at multiple levels and bring together multiple sources of variation in one probabilistic framework.…”

Tracheal instillation of urban PM2.5 suspension promotes acute cardiac polarization changes in rats

“…Epidemiologic studies have also demonstrated a consistent link between sudden cardiac death and particulate air pollution (16), with changes such as increased QRS duration and arrhythmias (17), alteration of heart rate variability (HRV) (18,19) and repolarization abnormalities (20)(21)(22)(23) increasing morbidity and mortality. Previous epidemiological studies have shown that daily variations in particulate air pollution induced a decrease of HRV (24,25) and an increase of arrhythmias (26). Studies focusing on the onset of myocardial infarction in patients exposed to traffic in their routine activities indicated that the most critical time window is within one hour of the onset of clinical manifestations (27).…”