Jeanjean A P R, Gallagher J, Monks P S, Leigh R J
Department of Physics and Astronomy, University of Leicester, Leicester, UK.
Department of Civil, Structural and Environmental Engineering, Trinity College Dublin, Ireland; School of Environment, Natural Resources and Geography, Bangor University, UK.
Environ Pollut. 2017 Jun;225:587-597. doi: 10.1016/j.envpol.2017.03.027. Epub 2017 Mar 21.
Air pollution continues to be a problem in the urban environment. A range of different pollutant mitigation strategies that promote dispersion and deposition exist, but there is little evidence with respect to their comparative performance from both an environmental and economic perspective. This paper focuses on examining different NO mitigation strategies such as trees, buildings facades coated with photocatalytic paint and solid barriers in Oxford Street in London. The case study findings will support ranking the environmental and economic impacts of these different strategies to improve personal exposure conditions on the footpath and on the road in a real urban street canyon. CFD simulations of airflow and NO dispersion in Oxford Street in London were undertaken using the OpenFOAM software platform with the k-ε model, taking into account local prevailing wind conditions. Trees are shown to be the most cost-effective strategy, with a small reduction in NO concentrations of up to 0.7% on the road. However, solid barriers with and without the application of photocatalytic paint and an innovative material (20 times more expensive than trees) can improve air quality on the footpaths more substantially, up to 7.4%, yet this has a significant detrimental impact on NO concentrations (≤23.8%) on the road. Photocatalytic paint on building surfaces presented a minimal environmental reductions (1.2%) and economic (>100 times more expensive than trees) mitigation strategy. The findings recognised the differences between footpath and road concentrations occurred and that a focused examination of three pollution hotspots can provide more cost effective pollution mitigation. This study considers how a number of pollutant mitigation measures can be applied in a single street canyon and demonstrates the strengths and weaknesses of these strategies from economic and environmental perspectives. Further research is required to extrapolate the findings presented here to different street geometries.
空气污染在城市环境中仍然是一个问题。虽然存在一系列促进污染物扩散和沉降的不同减排策略，但从环境和经济角度来看，关于它们相对性能的证据却很少。本文重点研究不同的氮氧化物减排策略，如树木、涂有光催化涂料的建筑外墙以及伦敦牛津街的固体屏障。该案例研究结果将有助于对这些不同策略的环境和经济影响进行排名，以改善真实城市街道峡谷中人行道和道路上的个人暴露条件。利用OpenFOAM软件平台和k-ε模型，结合当地盛行风况，对伦敦牛津街的气流和氮氧化物扩散进行了计算流体动力学（CFD）模拟。结果表明，树木是最具成本效益的策略，道路上氮氧化物浓度最多可小幅降低0.7%。然而，无论是否涂有光催化涂料以及使用一种创新材料（比树木贵20倍）的固体屏障，都能更显著地改善人行道上的空气质量，最多可改善7.4%，但这对道路上的氮氧化物浓度有显著的不利影响（≤23.8%）。建筑表面的光催化涂料对环境的减排作用最小（1.2%），且是一种经济成本很高的（比树木贵100倍以上）减排策略。研究结果认识到人行道和道路上污染物浓度存在差异，并且对三个污染热点进行重点研究可以提供更具成本效益的污染减排方案。本研究考虑了如何在单个街道峡谷中应用多种污染物减排措施，并从经济和环境角度展示了这些策略的优缺点。需要进一步研究将此处呈现的研究结果推广到不同的街道几何形状。
