We investigated whether PM2.5-mediated autonomic modulation depends on individual coronary risk profiles.
Five-minute average heart rate (HR) and heart rate variability (HRV, including standard deviation of normal-to-normal intervals [SDNN], square root of the mean squared differences of successive NN intervals [rMSSD], high frequency [HF]) were measured from 24-hour ambulatory electrocardiograms, and personal PM2.5 exposures were monitored in a prospective study of 10 male boilermakers (aged 34.3 ± 8.1 years). We used the Framingham score to classify individuals into low (score = 1–3) and high (score = 5–6) risk categories. Mixed-effect models were used for statistical analyses.
Each 1-mg/m3 increase in the preceding 4-hour moving average PM2.5 was associated with HR increase (5.3 beats/min) and HRV reduction (11.7%, confidence interval [CI] = 6.2–17.1% for SDNN; 11.1%, CI = 3.1–19.1% for rMSSD; 16.6%, CI = 1.5–31.7% for HF). Greater responses (2- to 4-fold differences) were observed in high-risk subjects than in low-risk subjects.
Our study suggests that adverse autonomic responses to metal particulate are aggravated in workers with higher coronary risk profiles.
From the Harvard School of Public Health (Drs Chen, Kim, Herrick, and Christiani), the Brigham and Women’s Hospital (Dr Stone, Ms MacCallum), and Beth Israel Deaconess Medical Center (Drs. Verrier, Nearing), Boston, Massachusetts; and the University of North Carolina School of Public Health (Drs Chen, You, and Zhou), Chapel Hill, North Carolina.
CME Available for this Article at ACOEM.org
This study was supported by NIH grants ES09860 and ES00002.
Jiu-Chiuan Chen has no commercial interest associated with this research.
Address correspondence to: David C. Christiani, MD, MPH, MS, Harvard School of Public Health, Rm. 1402, HSPH-1, 655 Huntington Avenue, Boston, MA 02115; E-mail: firstname.lastname@example.org.