Department of Civil and Environmental Engineering, Universidad de Los Andes, Cra. 1E No. 19A - 40, Bogotá, Colombia 111711.
Chemical Engineering Program, Universidad de la Salle Cra. 2 No. 10-70, Bogotá, Colombia 111711.
Environ Sci Technol. 2022 Jun 7;56(11):7096-7106. doi: 10.1021/acs.est.1c07004. Epub 2022 Mar 25.
Commuters are often exposed to higher concentrations of air pollutants due to its proximity to mobile sources. Despite recent trends in urban transport toward zero- and low-tailpipe emission alternatives, the assessments of the impact of these transformations on commuter exposure are limited by the low frequency of such studies. In this work, we use a unique data set of personal exposure concentration measurements collected over the span of 5 years to analyze changes due to the introduction of a new fleet for Bogotá's Bus Rapid Transit System. In that system, over a thousand Euro-II and -III diesel-powered buses were replaced with Euro-VI compressed natural gas and filter-equipped Euro-V diesel buses. We measured personal exposure concentrations of equivalent black carbon (eBC), fine particulate (PM), and ultra fine particles (UFP) during and after the retirement of old buses and the introduction of new ones. Observations collected prior to the fleet renewal were used as baseline and later compared to data collected over two follow-up campaigns in 2019 and 2020. Significant reductions in the concentration of PM and eBC were observed during the 2019 campaign, with a 48% decrease for mean in-bus eBC (89.9 to 46.4 μg m) and PM (180.7 to 95.4 μg m) concentrations. Further reductions were observed during the 2020 follow-up, when the fleet renovation was completed, with mean in-bus eBC decreasing to 17.7 μg m and PM to 42.3 μg m. These observations imply nearly a 5-fold reduction in eBC exposure and a 4-fold decrease in PM. There was a much smaller reduction of in-bus UFP concentration between 2019 and 2020, indicating a persistent presence of high particle number concentrations in the near-road environment despite the fleet renovation process. In-bus UFP concentrations ranged between 65 000 and 104 500 cm during the follow-up campaigns. The results in this work illustrate the immediate benefits of reducing personal exposure through the adoption of vehicles with more stringent emission standards.
通勤者由于靠近移动源，经常接触到更高浓度的空气污染物。尽管最近城市交通向零排放和低尾管排放替代品的趋势发展，但由于此类研究的频率较低，这些转变对通勤者暴露的影响评估仍受到限制。在这项工作中，我们使用了一个独特的个人暴露浓度测量数据集，该数据集收集了 5 年的时间，以分析由于引入新的波哥大快速公交系统而导致的变化。在该系统中，超过 1000 辆欧二和欧三柴油动力巴士被更换为欧六压缩天然气和配备过滤器的欧五柴油巴士。我们测量了个人暴露于等效黑碳 (eBC)、细颗粒物 (PM) 和超细颗粒 (UFP) 的浓度，分别在旧巴士退役和新巴士引入期间和之后进行测量。在车队更新之前收集的观测结果被用作基线，然后与 2019 年和 2020 年的两次后续活动中收集的数据进行比较。在 2019 年的活动中，观察到 PM 和 eBC 的浓度显著降低，平均车内 eBC(从 89.9 到 46.4 μg/m)和 PM(从 180.7 到 95.4 μg/m)浓度降低了 48%。在 2020 年的后续活动中，当车队翻新完成时，观察到进一步的降低，平均车内 eBC 降低到 17.7 μg/m，PM 降低到 42.3 μg/m。这些观测结果意味着 eBC 暴露减少了近 5 倍，PM 减少了 4 倍。2019 年至 2020 年间，车内 UFP 浓度的降低幅度要小得多，这表明尽管进行了车队翻新，但近路环境中高粒子数浓度仍持续存在。在后续活动期间，车内 UFP 浓度在 65,000 至 104,500 cm 之间。这项工作的结果说明了通过采用更严格排放标准的车辆来减少个人暴露的直接好处。
