Effects of Personal Exposure to Ambient Fine Particulate Matter on Acute Change in Nocturnal Heart Rate Variability in Subjects Without Overt Heart Disease

Abstract

The immediate effect within minutes to hours of personal exposure to ambient fine particulate matter (PM2.5) on cardiac autonomic function is limited, particularly at night. Our study aimed to assess the lagged association between personal exposure to PM2.5 and nocturnal heart rate variability (HRV). Repeated measures panel study among 21 community adults recruited from a local health clinic during the period of March 1, 2004 to August 31, 2004, in Boston, Massachusetts, in the United States. Ambulatory electrocardiogram (ECG) and continuous monitoring of personal exposure to PM2.5 and were measured for up to two consecutive days. We calculated 5-min time-specific average PM2.5 exposure for each participant. Mixed effects models were fit for 5-min standard deviation of normal-to-normal intervals (SDNN) and 5-min heart rate (HR) in relation to 5-min PM2.5 exposure lagged in 5-min intervals up to 4 hours. We found an 8.4% decrease in nocturnal SDNN (95% CI: −11.3% to −5.5%) and a 1.9% increase in nighttime HR (95% CI: 1.1% to 2.7%) for an interquartile range (IQR) increase in PM2.5 (13.6 µg/m3), after adjusting for confounders. Significant decreases in nocturnal SDNN associated with PM2.5 exposure occurred within 2.5 hours. The largest decrease in nocturnal SDNN of −12.8% (95% CI: −16.4 to −9.1%) that was associated with PM2.5 exposure was found with a lag of 25 minutes. Rapid changes in nocturnal HRV associated with personal PM2.5 exposure occurred within the previous 2.5 hours, with the largest effects at 25 minutes, suggesting immediate cardiac autonomic effects of fine particulate exposure.

Particulate Matter Exposure and Stress Hormone Levels

“…[5][6][7] In addition, several studies have reported an association between PM exposure and dysfunction of the automatic nervous system, which is known to increase cardiovascular risk. [8][9][10] Animal studies further implicated PM 2.5 as a stressor to the central nervous system that might induce a cascade of neuroendocrine responses.11,12 These provocative findings warrant mechanistic investigations in humans.In the past decade, metabolomics has emerged as a powerful tool to understand metabolic changes, particularly of small molecules (<1000 Da), in response to pathophysiological conditions or environmental exposures. 13 With high-throughput technologies such as chromatography coupled with mass spectrometry or nuclear magnetic resonance spectroscopy, metabolomic analysis can efficiently separate and quantify a large number of compounds from a single biological sample, and thus identify novel molecules and pathways that are affected by diseases or environmental exposures.…”

“…[5][6][7] In addition, several studies have reported an association between PM exposure and dysfunction of the automatic nervous system, which is known to increase cardiovascular risk. [8][9][10] Animal studies further implicated PM 2.5 as a stressor to the central nervous system that might induce a cascade of neuroendocrine responses. 11,12 These provocative findings warrant mechanistic investigations in humans.…”

Exposure to Fine Particulate Matter Leads to Rapid Heart Rate Variability Changes

“…In line with these ill-health effects of PM was the observation that PM 2.5 exposure is associated with reduced HRV: in controlled exposure of rats to PM 2.5 , HRV was reduced during ongoing exposure (Wagner et al, 2014). In a series of epidemiological (Pope et al, 2003;Wu et al, 2010;Huang et al, 2014;Nyhan et al, 2014;Mordukhovich et al, 2015;Lee et al, 2016) as well as controlled PM-exposure (Devlin et al, 2003;Weichenthal et al, 2014;Cole-Hunter et al, 2015;Hemmingsen et al, 2015) studies, small reductions in HRV within an hour after PM exposure were observed. However, a recent meta-analysis of panel studies investigating HRV effects of PM 2.5 (Buteau and Goldberg, 2016) questioned the association between PM 2.5 and frequently used indices of HRV.…”

Impacts of In-Cabin Exposure to Size-Fractionated Particulate Matters and Carbon Monoxide on Changes in Heart Rate Variability for Healthy Public Transit Commuters

“…The HRV measurement is relatively simple and feasible, so many environmental epidemiological studies adopt the HRV to explore the relationship between environmental air pollutants and human cardiovascular health. Too low HRV represents reduced dynamic complexity, adaptability, and ability to overcome continuous changes in the environment [16,19,20].…”

“…Panel studies have been adopted to investigate the short-term effects of outdoor PM pollution across a wide range of environmental settings [21]. Although previous studies have found that PM is associated with the changes in HRV, and the effect of particulates on HRV changes varies with particle sizes [20,22,23], current research into the effects of particulate exposure on cardiovascular functions and those of ANS on public transit is still limited, especially for healthy young populations [16,24]. Therefore, this panel study used HRV to assess the effects of traffic-related air pollution on cardiovascular functions, by simultaneously monitoring PM and carbon monoxide (CO) exposures as well as HRV on healthy young commuters who are exposed to size-fractionated PMs and CO on public transit.…”