Effects of Pm1, Pm2.5 and Pm10 on Heart Rate Variability in Susceptible Populations

ISEE-33 Introduction: Researches have shown that both of the elderly people and the cardio-vascular patients are susceptible populations for air pollution. The decreases in heart rate variability (HRV) are important indices of health effect caused by ambient air pollutants. The objective of this study was to investigate the short-term effects of particulate matter (PM) on HRV parameters in susceptible population. Method: The study population consisted of 29 volunteers aged from 46 to 75 yrs, with 11 of them suffering from coronary heat disease. Personal PM exposures were measured using direct-reading portable dust monitor (GRIMM Model 1.108, Germany) in 1 minute interval, while each subject’s 24-hour electrocardiographics were recorded by PacerCorder holter recorder (DELMAR Medical LLC, Model 461A, CA, USA). For each subject, health status and environmental factors were assessed by questionnaire and activity diary. The mass concentrations of PM1, PM2.5 and PM10 were measured and recorded as 5-minute average, and 1-hour, 2-hour, 3-hour, 4-hour, 5-hour, 6-hour, 7-hour, and 8-hour moving averages. Linear mixed-effects model were applied to estimate the effects of PM concentrations on time domain measures and frequency domain measures of HRV. Time domain HRV parameters included the standard deviation of normal RR intervals (SDNN), the square root of the mean of the squared differences between adjacent normal RR intervals (r-MSSD), and the probability of NN intervals more than 50 microsecond (pNN50). Frequency domain HRV parameters included low frequency (LF), high frequency (HF), LF/HF ratio, and Total Power. Results: After adjusting for gender, age, body mass index, smoking, sleeping hours, ?-block medicine, disease type, temperature, and relative humidity, the 4-hour moving averages of PM concentrations were found to have the strongest impact on HRV parameters. When the 4-hour PM10 levels increased 100?g/m3, the percentage changes of heart rate, SDNN, r-MSSD, pNN50, LF, HF, LF/HF, and Total Power were 0.49%, −4.96%, −6.95%, −0.84%, −6.86%, −6.02%, −0.38%, and −4.73%, respectively (all p<0.05). Similarly, when the 4-hour PM2.5 average increased 100mg/m3, the percentage changes of above parameters were 0.44%, −5.44%, −7.76%, −0.96%, −7.54%, −6.43%, −0.41%, and −5.09%, respectively (all p<0.05). When the 4-hour moving PM1 average increased 100mg/m3, the percentage changes of above parameters were 0.50%, −6.21%, −8.87%, −1.09%, −8.53%, −7.33%, −0.42%, and −5.71% (all p<0.05). Conclusions: Results of our study indicated that particulate matters may have both of the short-term effects and the delay effects on heart rate variability in susceptible populations. The fine particles showed more prominent effects than coarse particles on heart rate variability.