Department of Occupational and Environmental Health Sciences, Peking University School of Public Health, Beijing, China.
Sci Total Environ. 2011 Jun 1;409(13):2478-85. doi: 10.1016/j.scitotenv.2011.03.034. Epub 2011 Apr 13.
Carbonaceous and metallic components of particles have been shown to play a role in particles' effects on cardiac autonomic function as measured by heart rate variability (HRV). Previously we reported the association of HRV with marked changes in traffic-related particulate air pollution around the Beijing 2008 Olympic Games in a panel of taxi drivers.
We further investigated the relationship between exposures to the carbonaceous and metallic components of traffic-related particles and HRV in the same population.
Repeated measurements of in-car exposures to particulate matter ≤ 2.5 μm in aerodynamic diameter (PM₂.₅), carbon monoxide and nitrogen oxides were conducted in a group of 14 taxi drivers for one work shift in four study periods around the Beijing 2008 Olympics. The quantities of organic/elemental carbons and 27 elements of the in-car PM₂.₅ mass were determined laboratorially. Linear mixed-effects models were used to evaluate the impact of exposures to different PM₂.₅ components on HRV while controlling for potential confounders.
Taxi drivers' exposures to in-car PM₂.₅ and its components showed dramatic changes across the four study periods around the Beijing 2008 Olympics. Differences in associations of in-car PM₂.₅ components with HRV were found. An interquartile range (IQR: 917.9 ng/m³) increase in calcium was associated with a 5.48 millisecond [ms, 95% confidence interval (CI): 0.71, 10.24] increase in standard deviations of normal-to-normal (SDNN) intervals, while an IQR (4.1 ng/m³) increase in nickel was associated with a 1.53 ms (95% CI: 0.14, 2.92) increase in SDNN index. Additionally, a decline of 8.11 ms (95% CI: -15.26, -0.97) in SDNN per IQR (481.4 ng/m³) increase in iron was also found.
The results support associations of PM₂.₅ metallic components with HRV in younger healthy individuals. Future studies are needed to clarify the interaction among different PM₂.₅ components or the role of PM₂.₅ mixtures.
已证实，颗粒物质中的碳质和金属成分在通过心率变异性（HRV）测量的心脏自主功能的颗粒影响方面发挥了作用。此前，我们曾报道过，在一组出租车司机中，北京 2008 年奥运会前后，交通相关颗粒物空气污染的明显变化与 HRV 之间存在关联。
我们进一步调查了在同一人群中，交通相关颗粒的碳质和金属成分暴露与 HRV 之间的关系。
在 2008 年北京奥运会前后的四个研究期间，对 14 名出租车司机的一次轮班工作中，对车内可吸入颗粒物（PM₂.₅）、一氧化碳和氮氧化物的暴露情况进行了重复测量。实验室确定了车内 PM₂.₅质量中的有机/元素碳和 27 种元素的数量。线性混合效应模型用于评估控制潜在混杂因素后，不同 PM₂.₅ 成分暴露对 HRV 的影响。
出租车司机在 2008 年北京奥运会前后四个研究期间的车内 PM₂.₅及其成分暴露发生了显著变化。车内 PM₂.₅ 成分与 HRV 之间的关联存在差异。与四分位距（IQR：917.9ng/m³）增加钙相关的标准偏差正常到正常（SDNN）间隔增加 5.48 毫秒[ms，95%置信区间（CI）：0.71，10.24]，而与四分位距（4.1ng/m³）增加镍相关的 SDNN 指数增加 1.53ms（95%CI：0.14，2.92）。此外，还发现 IQR（481.4ng/m³）增加铁，SDNN 下降 8.11ms（95%CI：-15.26，-0.97）。
这些结果支持 PM₂.₅ 金属成分与年轻健康个体的 HRV 之间存在关联。需要进一步的研究来阐明不同 PM₂.₅ 成分之间的相互作用或 PM₂.₅ 混合物的作用。
