Obesity Is A Modifier of Autonomic Cardiac Responses to Fine Metal Particulates

BACKGROUND Increasing evidence suggests that obesity may impart greater susceptibility to adverse effects of air pollution. Particulate matter, especially PM(2.5) (particulate matter with aero-dynamic diameter /= 30 kg/m(2) were classified as obese. Mixed-effect models were used for statistical analyses. RESULTS Half (50%) of the study subjects were obese. After adjustment for confounders, each 1-mg/m(3) increase in 4-hr moving average PM(2.5) was associated with HR increase of 5.9 bpm [95% confidence interval (CI), 4.2 to 7.7] and with 5-min HRV reduction by 6.5% (95% CI, 1.9 to 11.3%) for SDNN, 1.7% (95% CI, -4.9 to 8.4%) for rMSSD, and 8.8% (95% CI, -3.8 to 21.3%) for HF. Obese individuals had greater PM(2.5)-mediated HRV reductions (2- to 3-fold differences) than nonobese individuals, and had more PM(2.5)-mediated HR increases (9-bpm vs. 4-bpm increase in HR for each 1-mg/m(3) increase in PM(2.5); p < 0.001). CONCLUSIONS Our study revealed greater autonomic cardiac responses to metal particulates in obese workers, supporting the hypothesis that obesity may impart greater susceptibility to acute cardiovascular effects of fine particles.