Department of Family Medicine, College of Human Medicine, Michigan State University, East Lansing, Michigan, USA.
Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA.
Am J Hypertens. 2019 Oct 16;32(11):1054-1065. doi: 10.1093/ajh/hpz113.
The risk for cardiovascular events increases within hours of near-roadway exposures. We aimed to determine the traffic-related air pollution (TRAP) and biological mechanisms involved and if reducing particulate matter <2.5 µm (PM2.5) inhalation is protective.
Fifty healthy-adults underwent multiple 2-hour near-roadway exposures (Tuesdays to Fridays) in Ann Arbor during 2 separate weeks (randomized to wear an N95 respirator during 1 week). Monday both weeks, participants rested 2 hours in an exam room (once wearing an N95 respirator). Brachial blood pressure, aortic hemodynamics, and heart rate variability were repeatedly measured during exposures. Endothelial function (reactive hyperemia index [RHI]) was measured post-exposures (Thursdays). Black carbon (BC), total particle count (PC), PM2.5, noise and temperature were measured throughout exposures.
PM2.5 (9.3 ± 7.7 µg/m3), BC (1.3 ± 0.6 µg/m3), PC (8,375 ± 4,930 particles/cm3) and noise (69.2 ± 4.2 dB) were higher (P values <0.01) and aortic hemodynamic parameters trended worse while near-roadway (P values<0.15 vs. exam room). Other outcomes were unchanged. Aortic hemodynamics trended towards improvements with N95 respirator usage while near-roadway (P values<0.15 vs. no-use), whereas other outcomes remained unaffected. Higher near-roadway PC and BC exposures were associated with increases in aortic augmentation pressures (P values<0.05) and trends toward lower RHI (P values <0.2). N95 respirator usage did not mitigate these adverse responses (nonsignificant pollutant-respirator interactions). Near-roadway outdoor-temperature and noise were also associated with cardiovascular changes.
Exposure to real-world combustion-derived particulates in TRAP, even at relatively low concentrations, acutely worsened aortic hemodynamics. Our mixed findings regarding the health benefits of wearing N95 respirators support that further studies are needed to validate if they adequately protect against TRAP given their growing worldwide usage.
在靠近道路的地方暴露几个小时后，心血管事件的风险就会增加。我们旨在确定与交通相关的空气污染（TRAP）和相关的生物学机制，以及减少吸入小于 2.5µm 的颗粒物（PM2.5）是否具有保护作用。
50 名健康成年人在安阿伯市分两个不同的星期（随机分配在一个星期内佩戴 N95 口罩）进行了多次 2 小时的近路暴露（周二至周五）。在两个星期的星期一，参与者都在一个检查室休息 2 小时（一次佩戴 N95 口罩）。在暴露期间，反复测量肱动脉血压、主动脉血流动力学和心率变异性。在暴露后（星期四）测量内皮功能（反应性充血指数[RHI]）。在整个暴露过程中测量黑碳（BC）、总颗粒计数（PC）、PM2.5、噪声和温度。
PM2.5（9.3±7.7µg/m3）、BC（1.3±0.6µg/m3）、PC（8375±4930 个/cm3）和噪声（69.2±4.2dB）较高（P 值<0.01），且主动脉血流动力学参数在靠近道路时呈下降趋势（与检查室相比，P 值<0.15）。其他结果不变。佩戴 N95 口罩时，主动脉血流动力学在靠近道路时呈改善趋势（与不使用时相比，P 值<0.15），而其他结果则不受影响。较高的近路 PC 和 BC 暴露与主动脉增强压升高有关（P 值<0.05），且 RHI 呈下降趋势（P 值<0.2）。佩戴 N95 口罩并不能减轻这些不良反应（污染物-口罩相互作用无统计学意义）。近路的室外温度和噪声也与心血管变化有关。
即使在相对较低的浓度下，暴露于 TRAP 中的实际燃烧产生的颗粒也会急性恶化主动脉血流动力学。我们关于佩戴 N95 口罩的健康益处的混合发现支持，需要进一步的研究来验证它们是否能充分保护人们免受 TRAP 的影响，因为它们在全球范围内的使用越来越广泛。
