Effects of canyon geometry on the distribution of traffic-related air pollution in a large urban area: Implications of a multi-canyon air pollution dispersion model
Effects of canyon geometry on the distribution of traffic-related air pollution in a large urban area: Implications of a multi-canyon air pollution dispersion model
复制标题
DOI：
10.1016/j.atmosenv.2017.06.031
复制
发表时间：
2017-09-01
影响因子：
5
通讯作者：
Tao, Shu
中科院分区：
文献类型：
--
作者：
Fu, Xiangwen;Liu, Junfeng;Tao, Shu
街道峡谷在城市地区随处可见。街道峡谷中与交通有关的空气污染物会对人类健康产生不利影响。在本研究中，建立了考虑街道分布、峡谷几何、背景气象、交通分配、交通排放和空气污染物扩散的城市尺度交通污染扩散模型。在模型中，交通流产生的车辆尾气首先沿着计算流体动力学（CFD）模型产生的微尺度风场扩散到街道峡谷内。然后，污染物离开街道峡谷，进一步扩散到城市地区。在此基础上，研究了峡谷几何形状对北京市中心地区交通排放NO、CO分布的影响。我们发现，建筑高度的增加导致峡谷内的污染更严重，峡谷外的污染在行人水平上更低，导致该地区的区域平均浓度更高。此外，街道两侧建筑高度高度均匀或高度不均匀的峡谷往往会降低行人水平的城市尺度空气污染浓度。此外，增加街道宽度往往会同时减少排放和加强通风，从而降低污染物浓度。我们的研究结果表明，在人口稠密的城市地区，峡谷几何形状强烈影响人类对交通污染物的暴露。仔细规划街道布局和峡谷几何形状，同时考虑交通需求和当地天气模式，可能会显著减少城市居民吸入不健康空气。(C) 2017 Elsevier Ltd.版权所有。
Street canyons are ubiquitous in urban areas. Traffic-related air pollutants in street canyons can adversely affect human health. In this study, an urban-scale traffic pollution dispersion model is developed considering street distribution, canyon geometry, background meteorology, traffic assignment, traffic emissions and air pollutant dispersion. In the model, vehicle exhausts generated from traffic flows first disperse inside street canyons along the micro-scale wind field generated by computational fluid dynamics (CFD) model. Then, pollutants leave the street canyon and further disperse over the urban area. On the basis of this model, the effects of canyon geometry on the distribution of NO,, and CO from traffic emissions were studied over the center of Beijing. We found that an increase in building height leads to heavier pollution inside canyons and lower pollution outside canyons at pedestrian level, resulting in higher domain-averaged concentrations over the area. In addition, canyons with highly even or highly uneven building heights on each side of the street tend to lower the urban-scale air pollution concentrations at pedestrian level. Further, increasing street widths tends to lead to lower pollutant concentrations by reducing emissions and enhancing ventilation simultaneously. Our results indicate that canyon geometry strongly influences human exposure to traffic pollutants in the populated urban area. Carefully planning street layout and canyon geometry while considering traffic demand as well as local weather patterns may significantly reduce inhalation of unhealthy air by urban residents. (C) 2017 Elsevier Ltd. All rights reserved.