Building Green and Blue Spaces

Published on: 4 Dec, 2024
Updated on: 4 Dec, 2024

With house building a priority for the new UK Government, researchers at the University of Surrey are urging city planners not to forget to build “greening areas” such as parks in new communities.

Surrey’s Global Centre for Clean Air Research (GCARE), working with 30 co-authors from seven countries, found that parks may be the most effective solution for reducing overall air pollution – cutting air pollution by 22 per cent city-wide.

However, the study highlights the importance of evaluating how well different types of green, blue, and grey infrastructure (GBGI) work in smaller spaces and recognising that parks can include multiple features, which together enhance their impact.

The study also examined other common types of green, blue, and grey infrastructure (GBGI), such as trees, green walls, and hedges, and found mixed results for their ability to reduce air pollution.

Trees were most effective in open-road conditions, where they could cut pollution by up to 77%. However, the researchers discovered that planting trees in narrow, enclosed streets – known as street canyons –can sometimes worsen air quality. This is because certain tree species and arrangements can block airflow, trapping pollution.

Prof Prashant Kumar

Professor Prashant Kumar, lead author of the study and Founding Director of GCARE at the University of Surrey, and the Director of the RECLAIM, said:

“We are beginning to understand just how powerful green infrastructure can be against urban air pollution, but their effectiveness hinges on where and how they are implemented. Our review has found that well-placed greenery can cut black carbon levels by up to 40%, making our communities greener and healthier.”

The research is part of the RECLAIM (Reclaiming Forgotten Cities – Turning Cities from Vulnerable Spaces to Healthy Places for People) project. RECLAIM is a £1.45 million UK Research and Innovation-funded Network Plus initiative. It is led by GCARE in collaboration with the UK Centre for Ecology & Hydrology and the Universities of Bath, Bangor and Warwick.

According to the World Health Organization, ambient (outdoor) air pollution caused 4.2 million deaths in 2019. Major sources of outdoor air pollution include vehicles, power generation, and residential energy for cooking and heating.

Professor Kumar added: “We have discovered that many of the GBGI lack scientific evidence regarding their effectiveness in removing air pollution. Decisions are often based on expert judgments, and so it is crucial that we fill this knowledge gap as quickly as possible for informed decision-making and for maximising the potential of GBGI.”

Sam Peters

Local Green Party member Sam Peters, who has stood as a candidate in several local elections, said: “It is great to see ground-breaking work happening in Guildford on green/blue spaces, which are not only vital in tackling air pollution but also for preventing flooding, protecting biodiversity, improving mental and physical health, and more.

“GCARE’s world-leading research has also been put into practice locally. Urban greening projects at Sandfield School, situated on a busy crossroads, have significantly reduced pollution in the playground. I was very pleased to take part in similar projects at Guildford Nursery just next door, and am currently helping install green roofs on White Lion Walk as part of a group of volunteers from Zero Carbon Guildford and Surrey Wildlife Trust.

“However, it’s not enough to ‘build in’ green/blue spaces into new or existing communities as afterthoughts. Protecting our existing natural spaces (while ensuring access for all) and minimising air pollution through fundamental changes to transport, planning, heating and energy generation must be top priorities.”

The study has been published in the journal The Innovation Geoscience.