Blue-Green Infrastructure and Cleaner Air: A Systematic Literature Review for the UK

Air pollution is a widespread problem that impacts both indoor and outdoor spaces, posing serious risks to human health and well-being. Both short-term and long-term exposure to air pollution have detrimental effects on human health and the climate, increasing the risk of cardiovascular disorders, respiratory illnesses, and global warming. Many cities throughout the world, including those in the UK, have explored the potential of blue-green infrastructure (BGI) as a strategy in addressing air quality. BGI is a nature-friendly strategy of working with green spaces - such as street trees, parks or gardens; and blue elements such as rivers, wetlands, canals or lakes to address climate change and environmental degradation while promoting the creation of resilient and liveable cities. However, BGI’s efficacy varies depending on design, scale, and location; therefore, customised strategies are needed for various urban settings. According to this systematic review of the latest research (years 2015 to 2025) on BGI and air pollution; road-side trees, green walls, and wetlands as a blue infrastructure help in filtering outdoor pollutants. By reducing pollutant concentrations and fostering sustainable urban environments, green infrastructure may have a great potential to enhance outdoor air quality in comparison to indoor air quality. The systematic review also points out the need for policy frameworks to include evidence-based strategies into urban planning, ensuring that outdoor BGI is accessible, equitable, and effective in addressing air pollution and climate challenges. Trans-disciplinary research is necessary to optimise BGI deployment to develop future British cities that prioritise sustainability, clean air, and public health.