Exposure to sub-chronic and long-term particulate air pollution and heart rate variability in an elderly cohort: the Normative Aging Study.

Irina Mordukhovich,Brent Coull,Joel Schwartz,Petros Koutrakis,Pantel Vokonas,Itai Kloog

doi:10.1186/s12940-015-0074-z

Abstract

BackgroundShort-term particulate air pollution exposure is associated with reduced heart rate variability (HRV), a risk factor for cardiovascular morbidity and mortality, in many studies. Associations with sub-chronic or long-term exposures, however, have been sparsely investigated. We evaluated the effect of fine particulate matter (PM2.5) and black carbon (BC) exposures on HRV in an elderly cohort: the Normative Aging Study.MethodsWe measured power in high frequency (HF) and low frequency (LF), standard deviation of normal-to-normal intervals (SDNN), and the LF:HF ratio among participants from the Greater Boston area. Residential BC exposures for 540 men (1161 study visits, 2000–2011) were estimated using a spatio-temporal land use regression model, and residential PM2.5 exposures for 475 men (992 visits, 2003–2011) were modeled using a hybrid satellite based and land-use model. We evaluated associations between moving averages of sub-chronic (3–84 day) and long-term (1 year) pollutant exposure estimates and HRV parameters using linear mixed models.ResultsOne-standard deviation increases in sub-chronic, but not long-term, BC were associated with reduced HF, LF, and SDNN and an increased LF:HF ratio (e.g., 28 day BC: −2.3 % HF [95 % CI:−4.6, −0.02]). Sub-chronic and long-term PM2.5 showed evidence of relations to an increased LF and LF:HF ratio (e.g., 1 year PM: 21.0 % LF:HF [8.6, 34.8]), but not to HF or SDNN, though the effect estimates were very imprecise and mostly spanned the null.ConclusionsWe observed some evidence of a relation between longer-term BC and PM2.5 exposures and changes in HRV in an elderly cohort. While previous studies focused on short-term air pollution exposures, our results suggest that longer-term exposures may influence cardiac autonomic function.Electronic supplementary materialThe online version of this article (doi:10.1186/s12940-015-0074-z) contains supplementary material, which is available to authorized users.

Highlights

Short-term particulate air pollution exposure is associated with reduced heart rate variability (HRV), a risk factor for cardiovascular morbidity and mortality, in many studies
At this initial examination, participants evaluated for the association between black carbon (BC) and HRV presented with a mean age of 73.6 years; most (71 %) were former or current smokers, 20 % were diabetic and 25 % had a body mass index (BMI) > 30 kg/m2
We found some evidence of associations between increased short-term PM2.5 exposure estimates and decreases in high frequency (HF), low frequency (LF), and standard deviation of normal-tonormal intervals (SDNN), as well as increased LF:HF ratio, though the associated confidence intervals were very wide and many of the effect estimates were not statistically significant

Summary

Introduction

Short-term particulate air pollution exposure is associated with reduced heart rate variability (HRV), a risk factor for cardiovascular morbidity and mortality, in many studies. Particulate air pollution exposure is associated with cardiovascular mortality and morbidity in a multitude of epidemiologic studies, including at levels at or below EPA standards [1, 2]. Pathways potentially mediating this association include induction of systemic inflammation [3, 4] and oxidative stress [5, 6], as well as changes in. Many previous studies have used air pollution at a central site as the exposure metric, introducing potential exposure error

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