Urban vegetation has the potential to improve air quality as it promotes pollutant deposition and retention. Urban air quality models often include the effect vegetation have on pollution dispersion, however, processes involved in pollution removal by vegetation are often excluded or simplified and does not consider different vegetation characteristics. In this systematic review, we analyze the influence of the large interspecies variation in vegetation characteristics to identify the key factors affecting the removal of the major urban pollutants, particulate matter (PM) and nitrogen dioxide (NO₂) from the air through vegetation deposition. The aim is to identify key processes needed to represent vegetation characteristics in urban air quality modelling assessments.

We show that PM is mainly deposited to the leaf surface, and thus representation of characteristics affecting the aerodynamics from canopy down to leaf surface are important, such as branch/shoot complexity and leaf size, leaf surface roughness and hairiness. In addition, characteristics affecting PM retention capacity, resuspension and wash-off, include leaf surface roughness, hairiness and wax content. NO₂ is mainly deposited through stomatal uptake, and thus stomatal conductance and its responses to environmental conditions are key factors. These include response to solar radiation, vapour pressure deficit and soil moisture.

Representation of these vegetation characteristics in urban air quality models could greatly improve our ability to optimize the type and species of urban vegetation from an air quality perspective.

城市植被有可能改善空气质量，因为它促进污染物沉积和滞留。城市空气质量模型通常包括植被对污染扩散的影响，然而，植被去除污染所涉及的过程往往被排除或简化，并且没有考虑不同的植被特征。在本系统综述中，我们分析了植被特征的大种间变异的影响，以确定影响通过植被沉积从空气中去除主要城市污染物、颗粒物 (PM) 和二氧化氮 (NO _{2 ) 的关键因素。}目的是确定在城市空气质量建模评估中代表植被特征所需的关键过程。

我们表明 PM 主要沉积在叶表面，因此表征影响从冠层到叶表面的空气动力学的特征很重要，例如分枝/枝条复杂性和叶片大小、叶表面粗糙度和毛羽。此外，影响 PM 保留能力、再悬浮和冲洗的特性包括叶表面粗糙度、毛羽和蜡质含量。NO ₂主要通过气孔吸收沉积，因此气孔导度及其对环境条件的响应是关键因素。这些包括对太阳辐射、蒸汽压力不足和土壤水分的反应。

在城市空气质量模型中表示这些植被特征可以极大地提高我们从空气质量角度优化城市植被类型和物种的能力。