Centre for Green Technology, School of Civil and Environmental Engineering, University of Technology Sydney, NSW, 2007, Australia.
Centre for Wind, Waves and Water, School of Civil Engineering, The University of Sydney, NSW, 2006, Australia.
Environ Pollut. 2021 Jul 1;280:116971. doi: 10.1016/j.envpol.2021.116971. Epub 2021 Mar 20.
Urban street canyons formed by high-rise buildings restrict the dispersion of vehicle emissions, which pose severe health risks to the public by aggravating roadside air quality. However, this issue is often overlooked in city planning. This paper reviews the mechanisms controlling vehicle emission dispersion in urban street canyons and the strategies for managing roadside air pollution. Studies have shown that air pollution hotspots are not all attributed to heavy traffic and proper urban design can mitigate air pollution. The key factors include traffic conditions, canyon geometry, weather conditions and chemical reactions. Two categories of mitigation strategies are identified, namely traffic interventions and city planning. Popular traffic interventions for street canyons include low emission zones and congestion charges which can moderately improve roadside air quality. In comparison, city planning in terms of building geometry can significantly promote pollutant dispersion in street canyons. General design guidelines, such as lower canyon aspect ratio, alignment between streets and prevailing winds, non-uniform building heights and ground-level building porosity, may be encompassed in new development. Concurrently, in-street barriers are widely applicable to rectify the poor roadside air quality in existing street canyons. They are broadly classified into porous (e.g. trees and hedges) and solid (e.g. kerbside parked cars, noise fences and viaducts) barriers that utilize their aerodynamic advantages to ease roadside air pollution. Post-evaluations are needed to review these strategies by real-world field experiments and more detailed modelling in the practical perspective.
城市街道峡谷由高楼大厦形成，限制了车辆排放的扩散，这通过加剧路边空气质量对公众健康构成了严重威胁。然而，在城市规划中，这个问题经常被忽视。本文综述了控制城市街道峡谷中车辆排放扩散的机制以及管理路边空气污染的策略。研究表明，空气污染热点并非都归因于交通繁忙，适当的城市设计可以减轻空气污染。关键因素包括交通状况、峡谷几何形状、天气条件和化学反应。确定了两类缓解策略，即交通干预和城市规划。街道峡谷的流行交通干预措施包括低排放区和拥堵收费，这可以适度改善路边空气质量。相比之下，从建筑几何形状角度进行城市规划可以显著促进街道峡谷中的污染物扩散。一般设计指南，例如较低的峡谷纵横比、街道与盛行风的对齐、非均匀的建筑高度和地面建筑孔隙率，可能包含在新的开发中。同时，街道内障碍物广泛适用于纠正现有街道峡谷中较差的路边空气质量。它们大致分为多孔（例如树木和树篱）和实体（例如路边停放的汽车、隔音墙和高架桥）障碍物，利用其空气动力学优势缓解路边空气污染。需要通过现实世界的现场实验和更详细的建模从实际角度来评估这些策略。
