| Personal Exposure to Submicrometer Particles and Heart Rate Variability in Human Subjects Chang-Chuan Chan,1 Kai-Jen Chuang,1 Guang-Ming Shiao,2 and Lian-Yu Lin3 1Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan; 2Chest Department, Taipei Veterans General Hospital, Taipei, Taiwan; 3Internal Medicine Department, National Taiwan University Hospital, Taipei, Taiwan Abstract
We conducted a study on two panels of human subjects--9 young adults and 10 elderly patients with lung function impairments--to evaluate whether submicrometer particulate air pollution was associated with heart rate variability (HRV) . We measured these subjects' electrocardiography and personal exposure to number concentrations of submicrometer particles with a size range of 0.02-1 µm (NC0.02-1) continuously during daytime periods. We used linear mixed-effects models to estimate the relationship between NC0.02-1 and log10-transformed HRV, including standard deviation of all normal-to-normal intervals (SDNN) , square root of the mean of the sum of the squares of differences between adjacent NN intervals (r-MSSD) , low frequency (LF, 0.04-0.15 Hz) , and high frequency (HF, 0.15-0.40 Hz) , adjusted for age, sex, body mass index, tobacco exposure, and temperature. For the young panel, a 10,000-particle/cm3 increase in NC0.02-1 with 1-4 hr moving average exposure was associated with 0.68-1.35% decreases in SDNN, 1.85-2.58% decreases in r-MSSD, 1.32-1.61% decreases in LF, and 1.57-2.60% decreases in HF. For the elderly panel, a 10,000-particle/cm3 increase in NC0.02-1 with 1-3 hr moving average exposure was associated with 1.72-3.00% decreases in SDNN, 2.72-4.65% decreases in r-MSSD, 3.34-5.04% decreases in LF, and 3.61-5.61% decreases in HF. In conclusion, exposure to NC0.02-1 was associated with decreases in both time-domain and frequency-domain HRV indices in human subjects. Key words: air pollution, autonomic system, epidemiology, heart rate variability, submicrometer particle. Environ Health Perspect 112:1063-1067 (2004) . doi:10.1289/ehp.6897 available via http://dx.doi.org/ [Online 4 March 2004]
Address correspondence to C.-C. Chan, Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Room 1447, 1st Section, No. 1 Jen-ai Rd., Taipei 100, Taiwan. Telephone/Fax: 886-2-2322-2362. E-mail: ccchan@ha.mc.ntu.edu.tw This study was supported by a grant from the National Science Council of Taiwan (NSC90-2320-B-002-126) . The authors declare they have no competing financial interests. Received 8 December 2003 ; accepted 4 March 2004.
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