Obesity is a modifier of autonomic cardiac responses to fine metal particulates.

BackgroundIncreasing evidence suggests that obesity may impart greater susceptibility to adverse effects of air pollution. Particulate matter, especially PM2.5 (particulate matter with aero-dynamic diameter ≤2.5 μm), is associated with increased cardiac events and reduction of heart rate variability (HRV).ObjectivesOur goal was to investigate whether particle-mediated autonomic modulation is aggravated in obese individuals.MethodsWe examined PM2.5-mediated acute effects on HRV and heart rate (HR) using 10 24-hr and 13 48-hr ambulatory electrocardiogram recordings collected from 18 boilermakers (39.5 ± 9.1 years of age) exposed to high levels of metal particulates. Average HR and 5-min HRV [SDNN: standard deviation of normal-to-normal intervals (NN); rMSSD: square-root of mean squared-differences of successive NN intervals; HF: high-frequency power 0.15–0.4 Hz] and personal PM2.5 exposures were continuously monitored. Subjects with body mass index ≥ 30 kg/m2 were classified as obese. Mixed-effect models we...