Division of Pulmonary Medicine, Department of Internal Medicine, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan.
Sci Total Environ. 2013 May 1;452-453:309-13. doi: 10.1016/j.scitotenv.2013.02.097. Epub 2013 Mar 22.
Exposure to traffic-related particulate matter (PM) is considered a potential risk for cardiovascular events. Little is known about whether improving air quality in car can modify cardiovascular effects among human subjects during commuting. We recruited a panel of 60 healthy subjects to commute for 2 h by a car equipped with an air conditioning (AC) system during the morning rush hour in Taipei. Operation modes of AC system using outside air (OA-mode), circulating inside air (IA-mode) and turning off (Off-mode) were examined. Repeated measurements of heart rate variability (HRV) indices, PM≤2.5 μm in aerodynamic diameter (PM2.5) and noise level were conducted for each participant in different modes during the commute. We used linear mixed-effects models to associate HRV indices with in-car PM2.5. We found that decreases in HRV indices were associated with increased levels of in-car PM2.5. For Off-mode, an interquartile range (IQR) increase in in-car PM2.5 with 15-min moving average was associated with 2.7% and 4.1% decreases in standard deviation of NN intervals (SDNN) and the square root of the mean of the sum of the squares of differences between adjacent NN intervals (r-MSSD), respectively. During OA and IA modes, participants showed slight decreases in SDNN (OA mode: 0.1%; IA mode: 1.3%) and r-MSSD (OA mode: 1.1%; IA mode: 1.8%) by an IQR increase in in-car PM2.5 with 15-min moving average. We concluded that in-car PM2.5 is associated with autonomic alteration. Utilization of the car's AC system can improve air quality and modify the effects of in-car PM2.5 on HRV indices among human subjects during the commute.
暴露于交通相关的颗粒物（PM）被认为是心血管事件的潜在风险。人们对汽车内空气质量的改善是否能改变人类在通勤过程中暴露于 PM 时的心血管效应知之甚少。我们招募了 60 名健康受试者，在台北早高峰时段乘坐配备空调（AC）系统的汽车通勤 2 小时。研究了使用外部空气（OA 模式）、循环内部空气（IA 模式）和关闭（关闭模式）的 AC 系统操作模式。在不同模式下，对每个参与者在通勤过程中的每一次重复测量心率变异性（HRV）指数、空气动力学直径（PM2.5）和噪声水平。我们使用线性混合效应模型将 HRV 指数与车内 PM2.5 相关联。我们发现，HRV 指数的下降与车内 PM2.5 水平的升高有关。在关闭模式下，车内 PM2.5 的 15 分钟移动平均值每增加一个四分位距（IQR），SDNN（标准差）和相邻 NN 间期均方根的平方根（r-MSSD）分别下降 2.7%和 4.1%。在 OA 和 IA 模式下，参与者的 SDNN（OA 模式：0.1%；IA 模式：1.3%）和 r-MSSD（OA 模式：1.1%；IA 模式：1.8%）略有下降，车内 PM2.5 的 IQR 增加了 15 分钟移动平均值。我们得出结论，车内 PM2.5 与自主神经改变有关。汽车空调系统的使用可以改善空气质量，并在人类受试者通勤过程中改变车内 PM2.5 对 HRV 指数的影响。
