Texas A&M Transportation Institute, 3135 TAMU, College Station, TX 77843-3135, USA.
Texas A&M Transportation Institute, 505 E. Huntland Dr., Suite 455, Austin, TX 78752, USA.
Sci Total Environ. 2019 Feb 15;651(Pt 1):154-161. doi: 10.1016/j.scitotenv.2018.09.169. Epub 2018 Sep 13.
Recent studies have suggested that automobile pollution poses significantly more harmful health impacts than previously realized. Light-rail transit (LRT) is a major type of transportation infrastructure, but there has been little research assessing the air quality effects of LRT based on the actual air pollution data. This study aimed to assess the effects of LRT on automobile-related air emissions in Houston. Specifically, we examined the effects of LRT on key tailpipe pollutants-carbon monoxide and acetylene-as well as other traffic pollution surrogates referred to as BTEX (benzene, toluene, ethylbenzene, and xylene), measured from ambient air monitoring stations. An interrupted time series design and analysis was used to determine the impact of an intervention, where the intervention was the opening of an LRT on January 1, 2004, with two years (2002-2003) of before and two years (2004-2005) of after period data. We found that, after controlling for weather, the opening of the LRT was associated with statistically significant reductions in traffic-related air emissions. Specifically, at the exposure sites, the daily maximum carbon monoxide level was reduced roughly by 24%, and the daily level of toluene was reduced roughly by 60% (33% after accounting for the reduction at the comparison site). Our findings lend support to the air quality benefits of LRT by providing suggestive evidence of positive effects of LRT based on actual air pollution monitoring data. This study's findings also emphasize the importance of developing effective measures to assess traffic-related pollution and call for advanced data collection strategies of additional data, including traffic volume and speed data.
最近的研究表明，汽车污染对健康的危害比之前认为的要大得多。轻轨交通（LRT）是一种主要的交通基础设施，但几乎没有研究根据实际空气污染数据来评估 LRT 对空气质量的影响。本研究旨在评估 LRT 对休斯顿汽车相关空气排放的影响。具体来说，我们研究了 LRT 对关键排气管污染物——一氧化碳和乙炔——以及其他被称为 BTEX（苯、甲苯、乙苯和二甲苯）的交通污染替代品的影响，这些污染物是从环境空气监测站测量得到的。采用中断时间序列设计和分析来确定干预措施的影响，干预措施是 2004 年 1 月 1 日开通的 LRT，有两年（2002-2003 年）的前测期和两年（2004-2005 年）的后测期数据。我们发现，在控制天气因素后，LRT 的开通与交通相关空气排放的统计学显著减少有关。具体来说，在暴露地点，一氧化碳的日最高水平降低了约 24%，甲苯的日水平降低了约 60%（考虑到对照地点的减少，降低了 33%）。我们的研究结果支持轻轨交通对空气质量的好处，提供了基于实际空气污染监测数据的轻轨交通具有积极影响的初步证据。本研究的结果还强调了制定有效措施评估交通相关污染的重要性，并呼吁采取更先进的数据收集策略，包括交通量和速度数据。
