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The Not So Green, Green Grass - How It's Impacting Air Quality

Recent research from the University of Sheffield has recommended that homeowners should be rewarded for gardening sustainably to help combat climate change and air pollution.


The research, carried out by Ross Cameron, Professor of Environmental Horticulture, calls for incentives, such as reduced council tax, to be introduced to encourage gardeners to use environmentally sensitive practices.

The research suggests well-planted gardens not only provide quality habitats for wildlife, but also improve local air quality, improve health and wellbeing, and provide people with the opportunity to grow their own food and connect with nature.


So how does garden management and design impact air quality?


Vegetation barriers such as hedges have an impact on climate change and air pollution

Well, where vegetated barriers are used to protect garden space from air pollution, for example from vehicles on adjacent roadways, certain types of plants (ones with fine leaves, hairs or waxy leaf cuticles) are particularly useful at absorbing particulate matter (del Carmen Redondo-Bermúdez et al. 2021).


According to a paper by María del Carmen Redondo-Bermúdez, Idris Tugrul Gulenc, Ross W. Cameron, and Beverley J. Inkson, it is known that trees and hedges can block and divert airflow containing air pollutants (Hewitt et al., 2019), inhibiting them from accumulating and reaching harmful levels. Additionally, particulate matter (PM) can be captured by the large surface area of foliage (McDonald et al., 2007), acting as a filter to clean desired areas.


Not only do hedges capture air pollutants, but they also reduce the risk of localised flooding (through intercepting rainfall), cool the proximate air, support wildlife and much more. So, it’s important to consider what to plant in your garden, particularly in areas such as garden borders, close to the road and traffic.


The not so green, green grass of home


 Artificial Grass has a negative impact on climate change and air pollution

Recently there has been a trend to convert vegetated garden space into hard-standing areas. Front gardens particularly, are commonly paved over to create off-road car parking. This, along with patio construction and a desire for lower maintenance gardens with artificial grass has resulted in the loss of vegetated areas (by 40–75 %) in the last two decades (Stobbelaar et al. 2021).


Professor Cameron recommends that at least 66 per cent of any garden should comprise permeable materials that allow water and air to infiltrate into the soil. Furthermore, he suggests that artificial grass covering an area in excess of 10 m2 should be prohibited.3


How can your garden promote better air quality?


Green gardens and vertical green spaces have an impact on climate change and air pollution

This article by Rachel Brown has a host of advice on how to create an air-quality garden. According to Brown, the Phyto-Sensor Toolkit by Professor Jennifer Gabrys at the University of Cambridge is a good place to start for advice on which plants make the best pollutant absorbers.


Hedges act as natural barriers to traffic and can also absorb pollutants. Bushy, hairy-leaved varieties such as Franchet’s Cotoneaster are particularly good at soaking up harmful particles. According to Dr Tijana Blanusa, ‘In just seven days a one-metre length of well-managed dense hedge will mop up the same amount of pollution that a car emits over a 500-mile drive.’


Trees help to purify our air by acting as a barrier and also trapping particulate matter. Confers, silver birch, yew and elder trees are all good for improving air quality.


Essentially, we should all try to make our gardens more ‘green’ than ‘grey’. But don’t worry if you already have paved gardens, you can always add greenery with a green wall (where vegetation grows vertically), green screens (a mesh on which climber vegetation can grow), or even a green roof!



References:

Cameron, R., 2022. ‘do We Need to See Gardens in a New Light?’ Recommendations for Policy and Practice to Improve the Ecosystem Services Derived from Domestic Gardens. [online]. Urban Forestry & Urban Greening. Available at: https://www.sciencedirect.com/science/article/pii/S1618866722003636?via%3Dihub#sec0015.


Del Carmen Redondo-Bermúdez, M., Abhijith, K.V., Chang, W.R., Chiam, Z., He, C., McDonald, A.G., Muhammad, S., Ottelé, M., Przybysz, A., Sæbø, A., Sgrigna, G., Shao, F., Song, Y., Tomson, M., Weerakkody, U., Xu, H., Zhang, L. and Bi, Y.F., 2021. ‘green Barriers’ for Air Pollutant Capture: Leaf Micromorphology as a Mechanism to Explain Plants Capacity to Capture Particulate Matter. [online]. Environmental Pollution. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0269749121013919.


Blanusa, T., 2015. Ecosystem Services Delivery by Urban Hedges. [online]. Ecosystem services delivery by urban hedges / RHS Gardening. Available at: https://www.rhs.org.uk/science/gardening-in-a-changing-world/environmental-projects/hedge-benefit.


Brown, R. and Robling, L., 2023. Air Pollution: How to Create an ‘air Quality’ Garden. [online]. Cocabana. Available at: https://www.cocabana.co.uk/blogs/our-cocabana-coconut-bowls/air-pollution-how-to-create-an-air-quality-garden-rachel-brown.


Garcin, S., 2023. PHYTO- SENSOR. [online]. Phyto-Sensor. Available at: https://phyto-sensor-toolkit.citizensense.net/.




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