Objective: To investigate the association between short-term exposure to indoor total volatile organic compounds (TVOC) and nocturnal heart rate variability (HRV) among young female adults.
Methods: This panel study recruited 50 young females from one university in Beijing, China from December 2021 to April 2022. All the participants underwent two sequential visits. During each visit, real time indoor TVOC concentration was monitored using an indoor air quality detector. The real time levels of indoor temperature, relative humidity, noise, carbon dioxide and fine particulate matter were monitored using a temperature and humidity meter, a noise meter, a carbon dioxide meter and a particulate counter, respectively. HRV parameters were measured using a 12-lead Holter. Mixed-effects models were used to evaluate the association between the TVOC and HRV parameters and establish the exposure-response relationships, and two-pollutant models were applied to examine the robustness of the results.
Results: The mean age of the 50 female subjects was (22.5±2.3) years, and the mean body mass index was (20.4±1.9) kg/m2. During this study, the median (interquartile range) of indoor TVOC concentrations was 0.069 (0.046) mg/m3, the median (interquartile range) of indoor temperature, relative humidity, carbon dioxide concentration, noise level and fine particulate matter concentration were 24.3 (2.7) ℃, 38.5% (15.0%), 0.1% (0.1%), 52.7 (5.8) dB(A) and 10.3 (21.5) μg/m3, respectively. Short-term exposure to indoor TVOC was associated with significant changes in time-domain and frequency-domain HRV parameters, and the exposure metric for most HRV parameters with the most significant changes was 1 h-moving average. Along with a 0.01 mg/m3 increment in 1 h-moving average concentration of indoor TVOC, this study observed decreases of 1.89% (95%CI: -2.28%, -1.50%) in standard deviation of all normal to normal intervals (SDNN), 1.92% (95%CI: -2.32%, -1.51%) in standard deviation of average normal to normal intervals (SDANN), 0.64% (95%CI: -1.13%, -0.14%) in percentage of adjacent NN intervals differing by more than 50 ms (pNN50), 3.52% (95%CI: -4.30%, -2.74%) in total power (TP), 5.01% (95%CI: -6.21%, -3.79%) in very low frequency (VLF) power, and 4.36% (95%CI: -5.16%, -3.55%) in low frequency (LF) power. The exposure-response curves showed that indoor TVOC was negatively correlated with SDNN, SDANN, TP, and VLF when the concentration exceeded 0.1 mg/m3. The two-pollutant models indicated that the results were generally robust after controlling indoor noise and fine particulate matter.
Conclusion: Short-term exposure to indoor TVOC was associated with significant negative changes in nocturnal HRV of young women. This study provides an important scientific basis for relevant prevention and control measures.
目的: 探究室内总挥发性有机物(total volatile organic compounds，TVOC)短期暴露与年轻女性夜间心率变异性(heart rate variability，HRV)的关联。
方法: 采用定组研究设计，于2021年12月至2022年4月期间对北京市某高校50名年轻女性进行两次重复调查。每次调查期间，使用室内空气质量检测仪对研究对象室内TVOC浓度进行实时监测。室内温湿度、噪声、二氧化碳和颗粒物浓度分别采用温湿度仪、噪声监测仪、二氧化碳仪及多通道颗粒物监测仪进行实时监测，并采用12导联动态心电图仪测量HRV指标。采用混合效应模型分析TVOC与HRV指标的关联及暴露-反应关系，并使用双污染物模型检验结果的稳定性。
结果: 50名女性的平均年龄为(22.5±2.3)岁，平均体重指数为(20.4±1.9) kg/m2。研究期间室内TVOC浓度的中位数(四分位间距)为0.069(0.046) mg/m3，室内温度、相对湿度、二氧化碳浓度、噪声水平及细颗粒物浓度的中位数(四分位间距)分别为24.3(2.7) ℃、38.5%(15.0%)、0.1%(0.1%)、52.7(5.8) dB(A)及10.3(21.5) μg/m3。室内TVOC短期暴露与研究对象HRV的时域及频域指标改变显著相关，且多数HRV指标发生最显著改变的暴露时间窗为1 h。室内TVOC的1 h滑动平均浓度每增加0.01 mg/m3，研究对象心跳间期标准偏差(standard deviation of all normal to normal intervals，SDNN)、连续5 min心跳间期平均标准偏差(standard deviation of average normal to normal intervals，SDANN)及相邻心跳差值超过50 ms与总正常心跳间距个数比值(percentage of adjacent normal to normal intervals differing by more than 50 ms，pNN50)分别降低1.89%(95%CI：-2.28%~-1.50%)、1.92%(95%CI：-2.32%~-1.51%)及0.64%(95%CI：-1.13%~-0.14%)，而总功率(total power，TP)、极低频功率(very low frequency power，VLF)及低频功率(low frequency power，LF)分别降低3.52%(95%CI：-4.30%~-2.74%)、5.01%(95%CI：-6.21%~-3.79%)及4.36%(95%CI：-5.16%~-3.55%)。暴露-反应关系曲线显示，当浓度超过0.1 mg/m3时，室内TVOC与SDNN、SDANN、TP、VLF线性负相关。双污染物模型提示，在控制室内噪声及细颗粒物因素后上述结果稳健。
结论: 室内TVOC短期暴露与年轻女性的夜间HRV改变存在负相关，本研究为相关防控措施提供了重要的科学依据。
Keywords: Air pollution, indoor; Female; Heart rate variability; Panel study; Volatile organic compounds.