Air quality improvement

The project features a vertical garden, or "living wall," on the facade of a residential building in Berlin’s Kreuzberg district. Constructed in 2016, the building replaced a WWII-damaged plot situated between two existing structures. With a strong emphasis on sustainability, the project minimizes its ecological footprint in various ways. The 660-square-meter plot retained original elements of the location’s history: the two surviving sections along Glogauer and Reichenberger Strasse were restored after the war, while the rubble from the destroyed corner was used to fill in the basement. This approach allowed the new construction to be built over the original foundations, preserving historical integrity while reducing construction costs and material use.
At the core of the building’s design is a green agenda, embodied in the vertical garden that helps absorb noise and pollution from the bustling street below, improving air quality for residents and passersby. The selection of winter-hardy plants ensures that the facade remains green year-round, while also cooling the surrounding area and mitigating the urban heat effect, which is especially valuable in densely populated neighborhoods. The greenery contributes to the local microclimate, providing both environmental and aesthetic benefits.
For residents, the garden is made accessible through rectangular box balconies that project from the green wall, allowing them to engage closely with the plants and enjoy the immersive garden atmosphere. The plants grow on a support structure that is securely anchored in the brickwork, receiving water and nutrients through an integrated, precision-controlled irrigation and fertilization system. Maintenance of the plants occurs twice a year, with new additions planted each spring to maintain the garden’s health and visual appeal.
The building itself, privately owned, contains a mix of holiday rentals and residential apartments. Architect Sarah Revière designed the project. (1-6)

Ireland’s native trees have developed over thousands of years, forming a vibrant ecosystem alongside surrounding plants, animals, fungi, and microbes. These trees provide critical habitats for plants and wildlife, offering essential food and shelter while producing oxygen vital to animals and humans alike. Historically, native trees supplied early Irish communities with fuel, food, shelter, and building materials. Today, they play a modern role in filtering dust, reducing pollution, and enriching urban spaces.
To highlight these benefits in Dublin, the Native Tree Trail in St. Anne's Park was created by DCC Parks and Landscape Services in 2008. This trail, featuring 15 different types of native trees, invites visitors to explore and appreciate the natural and cultural heritage of Ireland's native trees, underscoring the value of green spaces for both biodiversity and community well-being.
Strategic tree placement contributes to Dublin’s sustainability by reducing soil erosion, sequestering carbon, and mitigating urban heat. A green city is a healthy city, and preserving open spaces enhances its appeal as a place to live, work, and visit. The trail also plays an essential role in environmental education and community engagement. Over the years, St. Anne's Park has hosted multiple tree-planting events, including a 2019 collaboration with local schools for National Tree Week and National Tree Day, in partnership with the Tree Council of Ireland. The NGO has also offered family-friendly guided walks along the trail, helping to instill an appreciation for nature in visitors of all ages (1, 2, 3, 4, 5, p.93).

The Cinturón Verde de Independencia initiative is a pilot intervention that seeks to plant an urban forest in the lower middle-class district of Independencia (1) in the northern part of the urban territory (3). Here, 19% of the population lives in high-risk conditions, settled on steep slopes, and threatened by landslides (3).
It is part of a broader planning strategy that involves proposals engaging different levels of government (4). This project seeks to afforest the district's hillsides to improve the environment, reduce air pollution, improve the quality of life of its inhabitants, manage waste, regulate shade, control erosion, increase wild biodiversity, and provide spaces for environmental education (2). The Independence Green Belt is linked to a wide range of plans, projects, and decrees that have been developed by actors at different levels of government since 2016 (4). It works hand in hand with the EBA Lomas programme and seeks to create a green belt along the Lomas-city interface, which acts as a buffer zone for this sensitive ecosystem and creates a protective boundary against the expansion of irregular human settlements while providing a space for environmental awareness (2).
This program was developed by a consortium of multiple private, public, national, and international parties with strong community support (3). In two phases, an urban forest park of 4,800 of native trees irrigated with treated wastewater has been planted. During the first phase, PREDES planted 3,300 trees with USAID support in 2015, and another 1,500 were recently planted by PERIFERIA (consultants) (3).
The Independencia Green Belt occupies the hill areas of the district of the same name and relates to a possible metropolitan-scale buffer belt.
Its boundaries take advantage of the seven Sustainable Ecotourism Forest Parks (PFES) in the District Municipality of Independencia (MDI), as well as 115 hectares of the Amancaes Lomas (4). It aims to conserve 400 hectares (4).

The Heat Action Planning project in the Lindo Park-Roesley Park Neighborhood in Phoenix, Arizona, specifically addresses the heat-related challenges residents face in this area. Phoenix is particularly vulnerable to extreme heat events, and this project aims to provide both mitigation and adaptation strategies to reduce the direct impacts of heat and help residents cope more effectively with these conditions. As part of the city’s broader Heat Action Plan, the Lindo Park-Roesley Park initiative is one of three target areas, including Edison-Eastlake, just east of downtown Phoenix, and the Water Tower Improvement District in the City of Mesa. The project focuses on heat hazards such as extreme temperature events and the urban heat island effect, which disproportionately affect vulnerable populations.
This project is a collaborative effort, uniting a range of stakeholders including The Nature Conservancy, Maricopa County Department of Public Health, the Central Arizona Conservation Alliance, the Urban Resilience to Extremes Sustainability Research Network, Arizona State University’s Urban Climate Research Center, and the local residents. Together, these partners are working to develop comprehensive heat mitigation and adaptation strategies that address social equity and strengthen community engagement. Furthermore, the Heat Action Planning process was designed to serve as a model for future heat resilience efforts and create a local, contextual, and culturally appropriate vision of a safer, healthier future. The iterative planning and engagement method used by the project team strengthened relationships within and between
neighborhoods, community-based organizations, decision-makers, and the core team, and it combined storytelling wisdom and scientific evidence to better understand current and future challenges residents face during extreme heat events.The ultimate aim is to foster a more resilient and equitable neighborhood (1-7).

Phoenix faces substantial challenges related to extreme heat, air quality, and social inequity (1-11). The Phoenix Tree Equity Pledge, launched in 2021, is a comprehensive city-wide initiative focused on addressing urban tree inequity and reducing the effects of extreme heat, especially in communities most vulnerable to these conditions (1-12). Partnering with American Forests, the country’s oldest conservation nonprofit, the initiative aims to achieve “tree equity” by 2030, ensuring all neighborhoods receive the benefits trees offer (1).
To reach this goal, the city will focus on enhancing tree coverage in underserved neighborhoods through the development of a Residential Tree Equity Accelerator, which plans to plant 20,000 trees across 25 neighborhoods by 2030 (1-12). By utilizing the Tree Equity Score developed by American Forests, the city can monitor progress, identify areas of need, and measure the impact of these projects (2-4, 9, 11).
To foster public engagement, the initiative will collaborate with residents, businesses, and local organizations to support tree-related projects, raise awareness of the benefits of trees, and promote tree stewardship (1, 4, 15). Additionally, the project aims to create green opportunities within the community by establishing supportive policies and regulations for tree planting and care and by creating pathways to green jobs (1, 7-9, 13-14). Recognizing that heat affects communities unequally, the Tree Equity Pledge seeks to increase canopy coverage in targeted neighborhoods, improving air quality, reducing the urban heat island effect, and enhancing overall community health (1, 7-9, 13-14).

The Bahlui Forest project consists of a tree-planting initiative along the banks of the Bahlui River, which flows over a distance of 11 km through Iasi, practically dividing the city in two (1, 2, 6). The project aims to reduce the high levels of air pollution prevalent in the city, increase green spaces along the river and in the urban area, and enhance the aesthetic appeal of the surroundings, thereby improving the quality of life for local residents (1–3, 8, p. 188). The initiative was planned by the Municipality of Iași in collaboration with the Prut-Bârlad Water Basin Administration, the regional authority responsible for the river’s proper management (1–6). Furthermore, the "Ion Ionescu de la Brad" University of Agricultural Sciences and Veterinary Medicine in Iași provided the technical expertise needed to select and plant appropriate species (1–3, 7).
The planting completed in 2024, covers the river section between the Sf. Ioan bridge and the Stone Bridge (3–5). In total, 1,200 native species were planted, including four tree species—Willow, Malin, Red Maple, and Birch—and three shrub species (3–6).
This initiative is part of a broader municipal strategy to revitalize the riverbanks and address key issues (8, 9). Due to its natural geomorphology, the river represents a barrier in terms of accesibility between different parts of the city, and infrastructure and improvements need to be carried out to manage this problem (8 & 9). Therefore the areas around the river are sought to be revitalised to fullfil its touristic and recreational potential, ultimately becoming a green corridor and representing a new axis of development for Iasi (8, p. 344). Improving its green surfaces would also support efforts to increase green space sq.m. per inhabitant in the city, which falls short of the national requirement of 26 sq.m. per inhabitant (8, p. 189).

The Bosque Vertical do Centro Cultural de Belém (CCB) in Lisbon (Vertical Forest at CCB), designed by Francisco Caldeira Cabral, is an innovative vertical garden inaugurated in 2020. Spanning two 17-meter-high walls with 7,524 plant pots, it enhances urban biodiversity by attracting birds and insects (Ref 3). This project offers recreational and aesthetic benefits, making the entrance of the cultural centre into a green space (Ref 4).
The garden helps reduce air pollution by absorbing pollutants and producing oxygen. It uses a drop-by-drop irrigation system made from recycled PVC, ensuring efficient water usage and retention (Ref 1). Furthermore, the garden improves air quality, aims to mitigate urban heat island effects, and conserves water (Ref 2, Ref 5).

As part of the development of the neighbourhood around Opaltorget in Tynneryd, Gothenburg, a park has been thoroughly renovated. The area is being developed and renovated as part of a long-term, large-scale project to become more attractive, safe, and sustainable [Ref. 1]. The area has previously been classified as an exposed area, indicating socio-economic problems and relatively high crime rates [Ref. 7, 8]. The old park was considered an important part of the neighbourhood but was sometimes perceived as being unsafe or being used mainly as a passage area. The renovation aims to make the park safer, more attractive, and more accessible to residents [Ref. 1, 3]. The new park includes a playground, recreational areas, rainwater management and a diverse tree population promoting the delivery of several ecosystem services [Ref. 2]. Around the park, new residential buildings and a kindergarten have been constructed, and the adjacent square, a central spot of the neighbourhood for business and social interactions, has been renovated [Ref. 2, 4, 8, 10]

This project aimed to create an urban forest that will grow within Dublin’s Darndale Park, which is popular among students and sports clubs. The objective is to offer the community a green area where they can gather, appreciate nature, and enhance their knowledge about it. The new forest will act as a windbreak for the nearby fishing pond and aims to address challenges related to heatwaves that endanger the lives of young and elderly people. To foster a sense of inclusion and unity, the forest is designed in a doughnut shape, consisting of 3,000 native species like oaks, birch, willow, and hazel, with the trees forming the outer ring (1, 2). This urban forestation initiative is a component of the Uforest project, which is funded by the European Commission and supported by Etifor (environmental consulting company established within the Department of Land, Environment, Agriculture and Forestry of the University of Padua) and Ersaf (an instrumental body of the Lombardy Region) . The Uforest project seeks to enhance Europe's innovation capacity by fostering collaboration among universities, cities, and businesses to develop a novel approach to urban forestry (1).

Iasi has limited access to green-blue open spaces and fails to meet national and European standards for per capita green space and proximity to larger green areas. Additionally, the city experiences significant fragmentation in its green spaces. To address these issues, the municipality of Iasi launched a project in 2020 to restore a vacant and degraded area, transforming it into a park. Funded by European resources, the project aims to rehabilitate the neglected land by constructing a green park and introducing local vegetation. The primary goal is to provide a leisure and relaxation space for local citizens and visitors while improving the quality of the surrounding air by converting much of the terrain into green space. The vacant land is situated in the historic Ticau neighborhood, which has been affected by municipal neglect, characterized by poor infrastructure and limited connectivity to the city's main areas. Furthermore, the project aims to reduce the heat island effect by creating green oases in a city marked by many “hard surfaces,” such as paved areas, which contribute to this phenomenon expected to intensify in the coming years. Originally scheduled for completion by the end of 2022, the project has been delayed due to a lack of funds and is now expected to be finished by the end of 2024 (Refs 1, 2, 3, 4, 6, 7, 11).