The impact of trees on street ventilation, NOx and PM2.5 concentrations across heights in Marylebone Rd street canyon, central London

Buccolieri, Riccardo; Jeanjean, Antoine; Gatto, Elisa; Leigh, R. J.

doi:10.1016/j.scs.2018.05.030

Cited by 99 publications

(54 citation statements)

References 44 publications

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“…In such environments, high-level vegetation can limit the exchange of air from above, trapping pollution at ground level 29,50 . Although increased deposition may offset some of the decreases in dispersion potentially caused by trees in street canyons 51,52 , it is generally suggested that only lowlevel vegetation (or, in deep street canyons, only green walls) be implemented, in order to facilitate both dispersion and deposition 20 .…”

Section: Local Scalementioning

confidence: 99%

“…Under field conditions, dispersion bears an inextricable influence on deposition 20,77,81 . Recognising this, a number of recent studies have employed various integrated dispersion-deposition approaches to investigate impacts of GI 52,[82][83][84][85] . For example, Morakinyo and Lam 86 used such an approach in a CFD-based assessment of interactions between PM concentrations and vegetation barriers.…”

Section: Advantageous Aspects Of Gi For Air Qualitymentioning

confidence: 99%

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Designing vegetation barriers for urban air pollution abatement: a practical review for appropriate plant species selection

2020

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Vegetation can form a barrier between traffic emissions and adjacent areas, but the optimal configuration and plant composition of such green infrastructure (GI) are currently unclear. We examined the literature on aspects of GI that influence ambient air quality, with a particular focus on vegetation barriers in open-road environments. Findings were critically evaluated in order to identify principles for effective barrier design, and recommendations regarding plant selection were established with reference to relevant spatial scales. As an initial investigation into viable species for UK urban GI, we compiled data on 12 influential traits for 61 tree species, and created a supplementary plant selection framework. We found that if the scale of the intervention, the context and conditions of the site and the target air pollutant type are appreciated, the selection of plants that exhibit certain biophysical traits can enhance air pollution mitigation. For super-micrometre particles, advantageous leaf micromorphological traits include the presence of trichomes and ridges or grooves. Stomatal characteristics are more significant for sub-micrometre particle and gaseous pollutant uptake, although we found a comparative dearth of studies into such pollutants. Generally advantageous macromorphological traits include small leaf size and high leaf complexity, but optimal vegetation height, form and density depend on planting configuration with respect to the immediate physical environment. Biogenic volatile organic compound and pollen emissions can be minimised by appropriate species selection, although their significance varies with scale and context. While this review assembled evidence-based recommendations for practitioners, several important areas for future research were identified.

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Section: Local Scalementioning

confidence: 99%

Section: Advantageous Aspects Of Gi For Air Qualitymentioning

confidence: 99%

Designing vegetation barriers for urban air pollution abatement: a practical review for appropriate plant species selection

2020

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“…Higher ENI 1 values were assigned to sites with higher concentrations of air pollution, as they were considered to receive the greatest benefit from the GI in terms of air quality [21][22][23][24]. In particular, LID (planted-based types) reduces the concentrations of a variety of air pollutants that are known to increase health risks, such as fine atmospheric particulate matter (PM 2.5 ) [72,73]. In the proposed framework, PM 2.5 concentration was chosen as the indicator of overall air pollution, as is often done in the literature.…”

Section: Environmental Index (Eni) Developmentmentioning

confidence: 99%

The Low-Impact Development Demand Index: A New Approach to Identifying Locations for LID

Kaykhosravi

Abogadil

Khan

et al. 2019

Water

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The primary goal of low impact development (LID) is to capture urban stormwater runoff; however, multiple indirect benefits (environmental and socioeconomic benefits) also exist (e.g., improvements to human health and decreased air pollution). Identifying sites with the highest demand or need for LID ensures the maximization of all benefits. This is a spatial decision-making problem that has not been widely addressed in the literature and was the focus of this research. Previous research has focused on finding feasible sites for installing LID, whilst only considering insufficient criteria which represent the benefits of LID (either neglecting the hydrological and hydraulic benefits or indirect benefits). This research considered the hydrological and hydraulic, environmental, and socioeconomic benefits of LID to identify sites with the highest demand for LID. Specifically, a geospatial framework was proposed that uses publicly available data, hydrological-hydraulic principles, and a simple additive weighting (SAW) method within a hierarchical decision-making model. Three indices were developed to determine the LID demand: (1) hydrological-hydraulic index (HHI), (2) socioeconomic index (SEI), and (3) environmental index (ENI). The HHI was developed based on a heuristic model using hydrological-hydraulic principles and validated against the results of a physical model, the Hydrologic Engineering Center-Hydrologic Modeling System model (HEC-HMS). The other two indices were generated using the SAW hierarchical model and then incorporated into the HHI index to generate the LID demand index (LIDDI). The framework was applied to the City of Toronto, yielding results that are validated against historical flooding records.

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“…Urbanisation largely consists of removing native vegetation [1,2]. Plants that remain interact with air quality in a number of ways: poor air quality can be detrimental to plant growth [3][4][5], but tolerant plants may improve air quality [6,7]; in some cases, plants pollute air through emissions, or increase pollution by trapping air columns [8,9]. Understanding these complex interactions is bare rock-like substrates and skeletal soils, and therefore are pioneers and colonisers in urban areas.…”

Section: Introductionmentioning

confidence: 99%

Roadside Moss Turfs in South East Australia Capture More Particulate Matter Along an Urban Gradient than a Common Native Tree Species

et al. 2019

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Urbanisation largely consists of removing native vegetation. Plants that remain interact with air quality in complex ways. Pollutants can be detrimental to plant growth; plants sometimes reduce air quality, yet some species also improve it through phytoremediation. A common pollutant of concern to human health in urban areas is particulate matter (PM), small particles of solid or liquid. Our study compared roadside moss turfs with leaves of a common Australian tree species, Pittosporum undulatum, in their ability to capture PM along an urban gradient. We sampled nine sites, three in each of three levels of urbanisation: low, medium, and high according to road type (freeway, suburban road, quiet peri-urban road). In addition, we deployed a PM monitor over a two-week period in one site of each urban level to provide concentrations of PM2.5. We used chlorophyll fluorescence (Fv/Fm; maximum quantum yield of photosystem II) as a measure of plant stress. We extracted PM in three size fractions using a filtration and washing technique with water and chloroform. Site averages for moss turfs were between 5.60 and 33.00 mg per g dry weight for total PM compared to between 2.15 and 10.24 mg per g dry weight for the tree leaves. We found that moss was more sensitive to increasing urbanisation, both in terms of trapping proportionately more PM than the leaves, and also in terms of photosynthetic stress, with moss Fv/Fm declining by a site average of 40% from low to high urban “class” (0.76 to 0.45). Our study highlights the stressors potentially limiting moss persistence in cities. It also demonstrates its ability to trap PM, a trait that could be useful in urban applications relating to urban greening or air quality.

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The impact of trees on street ventilation, NOx and PM2.5 concentrations across heights in Marylebone Rd street canyon, central London

Cited by 99 publications

References 44 publications

Designing vegetation barriers for urban air pollution abatement: a practical review for appropriate plant species selection

Designing vegetation barriers for urban air pollution abatement: a practical review for appropriate plant species selection

The Low-Impact Development Demand Index: A New Approach to Identifying Locations for LID

Roadside Moss Turfs in South East Australia Capture More Particulate Matter Along an Urban Gradient than a Common Native Tree Species

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