Air quality improvement

The riparian forest of Montgérald, through which the “Monsieur” River flows, is located within Fort-de-France and boasts rich biodiversity, featuring around 100 species of shrubs and trees and about 30 animal species, including 16 types of birds. It is one of the last remnants of the mesophilic forest type and the only example in a French peri-urban setting. This unique ecosystem is recognized as a Natural Area of Ecological, Faunal, and Floral Interest (ZNIEFF) and a Classified Wooded Area (EBC), underscoring the need for conservation efforts.
Covering nearly 21 hectares, this site offers ecological benefits like air quality improvement and temperature regulation, providing a "fresh air island" near the city center. However, it faces significant challenges, including flooding caused by climate change and heavy rains, which exacerbate erosion along the Monsieur River. The area is also threatened by invasive alien species, making conservation measures even more crucial.
Since 2015, the municipality of Fort-de-France, along with project partners, has been working on developing this natural space for both conservation and public engagement purposes. The most recent actions occurred in 2020, including riverbank restoration, clearing invasive species, and creating walking paths and educational installations. Additionally, the project features an awareness campaign targeting local schools. The ongoing initiative aims to merge biodiversity conservation with community recreational use and environmental education, ensuring the resilience of this vital ecosystem against the impacts of climate change. (Refs. 1, 2, 3)

The Rimac River Special Landscape Project, developed by the Municipal Programme for the Recovery of the Historic Centre of Lima (PROLIMA), is a municipal proposal that arose as a response to the significant degradation of the Rimac River as it passes through the historic centre of the Peruvian capital. The river has lost its character as a green corridor and potential public recreational space for citizens (1, 3). The main problems affecting the river are related to the erosion and risk of flooding of the river space, the ecological degradation of its channels and banks, the disconnection and low quality of adjacent public spaces and the urban fragmentation caused by car-oriented mobility (2). To recover its essence as an ecological green corridor, it was proposed to give back to the Historical Centre its riverside identity and to recover the water, environmental and scenic landscape. This project aims to restore the Rímac to its role as a geographical heritage and backbone of the city of Lima, creating a system of accessible and sustainable public spaces that will help to recover this water, urban and historical landscape, as well as providing a better quality of life for the residents and users of the Historical Centre (1).
The project consists of 4 stages of intervention: Puente del Ejército - Puente Santa Rosa / Puente Santa Rosa - Puente Balta / Puente Balta - Límite
of the CHL to the east (5). Among the interventions that make up the Special River Landscape Project are: the renaturation of the 4 km of the Rimac River as it passes through the city, the construction of 14 parks, 7 squares, 1 tree planting project, 24 street renovation projects, 7 bridges/pedestrian walkways, 10 building rehabilitations and 2 new public facilities (4). It is planned to start implementing the project by the end of 2024 (4).

To protect the Lomas de Primavera from urban pressure and other threats, the Lomas de Primavera Ecological Association has implemented strategies for its conservation. One of the strategies this organisation has promoted is reforestation activities. Working together with the Municipality of Lima and other interested actors, they have sought to expand Lima's green spaces, improve air quality, enhance flora, and promote tourism, among other benefits (1). Lima's Municipality has supported the project by donating 20,000 trees for reforestation and to prevent land encroachment (1), social organisations and environmental activists have joint efforts to plant more than 250 trees to support the conservation efforts (2, 7).
The Lomas de Primavera Ecological Association leads the project, organizing community management efforts to conserve the Lomas de Primavera sector. This association is based in the Agrupación Familiar Primavera Lomas de Carabayllo community (2). The association's conservation activities involve collaboration with various stakeholders at different levels. Locally, it works with community leaders and organizations. At the district level, it coordinates with the Carabayllo municipality and the NGO CIDAP to improve urban conditions. The metropolitan-level collaboration includes the Municipality of Lima and the ACR 'Sistema de Lomas de Lima' for ecosystem protection and valorization. Nationally, it partners with MINAM, SERNANP, MINAGRI, UNDP, UCV, and the Network of Peruvian Lomas to enhance ecosystem services, restore degraded areas, and conduct research on the Lomas (2).
The preservation and reforestation of these ecosystems is essential, as they have social, cultural and environmental value, including the following ecosystem services: provision of genetic resources, soil formation, pollination, aesthetic services, ecotourism, food, education, and archaeological and historical services (3)

In 2020, the European Fund for the Balkans (EFB) launched the Trees of Friendship project, which plants over 400 trees annually across six Western Balkan capitals, known to be some of the most air-polluted cities in Europe (Ref. 5). Tirana has been involved from the start, having planted over 110 trees in locations such as Great Lake Park in 2020 and Farka Park in 2022 (Ref. 1,2).
The project is carried out with the support of local municipal and civil society partners, including Tirana's Parks and Recreation Agency and the Environmental Territorial Management Institute, along with activists and volunteers (Ref. 1,2). The initiative was planned in 2019 when the EFB board decided to mitigate its CO2 emissions from business-related flights and enhance local and regional cooperation on air pollution (Ref. 3,4,5). Despite challenges in citizen engagement during the COVID-19 pandemic, the Trees of Friendship project continues to raise awareness about the role of trees in mitigating the impact of air pollution on health and well-being (Ref. 2). Its strong and well-established local and regional partnerships have facilitated the project's implementation in the past and continue to benefit in scaling the project (Ref. 1,5).

In 2001, the local municipality of La Paz, in collaboration with the International Union of Architects (UIA), launched a design contest to create a central park within a protected natural area (3). The park's aim was to develop urban infrastructure while connecting nature with the city (3). The winning architectural design envisioned an infrastructure that would harmonize with the existing natural surroundings and minimize interference with the environment (4).
The park's implementation included pedestrian and bike pathways, numerous panoramic viewpoints, facilities for exercise and cultural events, buildings dedicated to science, historically significant monuments, playgrounds, and the rehabilitation and creation of multiple green spaces (1 & 4 to 6).
While most of the project was completed by 2009, the area's exposure to recurrent landslides, droughts, and illegal waste disposal, combined with ongoing degradation, has necessitated afforestation efforts and maintenance actions from the municipality to ensure the protection of the natural area and enhance its benefits (7 & 8). Recently, the park has been part of a national citizen monitoring program for species, which has improved the categorization of wildlife in the area (11 & 12). Additionally, 2,000 trees were planted in the park in 2023 as part of a reforestation campaign, and cleaning and watering maintenance work has been carried out to support their growth (7 & 13). This initiative is part of a larger project to revitalize the park (10 & 13).
Overall, the park aims to protect local wildlife and plant species while acting as a "green lung" for the city, regulating the climate, providing recreational spaces, and improving livability (14).

This initiative was launched by the local government of La Paz, focusing on afforestation of the Mallasa landfill, which was closed in 2004 (1-4 & 6-10). While some plantations were established in the area when the landfill was closed, the overall plan aimed to manage the waste until the site was sufficiently clean for new projects—a process expected to take at least a decade (6). By 2021, signs of biodiversity, including flora and fauna, had begun to return to the former landfill. In response, the municipality of La Paz implemented a project to plant 6,000 native tree species, along with other shrub species, to further enhance biodiversity regeneration and establish a second urban forest in the city (3 & 4 & 7 & 8).

The afforestation efforts took place between 2021 and 2022, coordinated through "forestry brigades" made up of diverse volunteer groups. These groups included members from public institutions, private company representatives, NGOs (both environmental and non-environmental), universities, religious organizations, and local citizen groups (8-10). A total of 12 hectares were reforested out of the 33-hectare area (1 & 7). Following this, the area was closed to the public and is expected to become a biodiversity sanctuary within ten years, with ongoing monitoring by the municipal environmental agency (7). Among the trees planted, some were chosen to attract birds with their fruit, others to support the pollination of hummingbirds and bees, while others were intended to enrich the soil with nutrients—all species being native to the region (3 & 7).

Additional goals of the initiative include raising awareness about climate change, fostering a sense of environmental stewardship through community engagement, and advancing the municipality's decarbonization plans (3 & 9). Some of the seedlings and saplings were purchased by the municipality at a cost of 6,160 euros, with private companies also contributing financial support to the initiative (1 & 7).

In an architecturally important area of Berlin, situated between the Landwehr Canal, the Kulturforum (the Berliner Philharmonie and the Berlin State Library) and the new construction on Potsdamer Platz, a combination of green and grey infrastructure has been realised to minimise the burden on Berlin’s existing water infrastructure.
Green and non-green roofs harvest annual rain, which flows through the site’s buildings and is used for toilet flushing, irrigation, and fire systems. The roofs retain and then release water to the large on-site buffer pond, which has five underground storage tanks. Next to the roofs, a series of urban ponds and connecting canals have been implemented, with a combined area of approximately 1.2 hectares. They are filled with rainwater, creating an oasis for urban life. Vegetated biotopes are integrated into the overland landscape and serve to filter and circulate the water that runs along streets and walkways. The lake’s water quality is excellent, forming a natural habitat for animals and cooling the surroundings, while fresh water usage in the buildings has been reduced. (Ref. 1; Ref. 2; Ref. 3; Ref. 6)
The project was implemented in the 1990s as part of the development of Potsdamer Platz in the wake of the reunification of Germany. Several architects collaborated on the implementation that was completely privately funded. Beyond its ecological and technical features, the site is a blue natural site in the heavily built city centre of Berlin and allows people to linger and enjoy natural features. The drainage system won several sustainability prices and is considered a successful integration of nature and technology-based mechanisms to foster climate change adaptation. As the rainwater system stores rainwater in underground tanks and ponds, the urban sewage system is relieved during heavy rain, and water can evaporate. Therefore, the small water circle is closed, and the microclimate is cooled. (Ref. 2; Ref. 6)

Located in the Lima district of San Isidro - the heart of commercial activity in Peru - the Real Dos Tower is a prime office building in the Centro Empresarial Real de San Isidro. It was inaugurated in 2018, and it is distributed over 23 levels (14 floors and 9 basements) and enjoys a landscaped green roof (1162 m2) at the crown of the building and numerous outdoor vertical gardens at full height (2365 m2) on the three main fronts (1, 4). This project was a finalist in the 2018 Mipim Awards, considered the ‘Oscars’ of world architecture, and stood out for its architecture and design, due to its attributes of innovation and sustainability (2).
This building has managed to create harmony between design and efficient use of resources. It is characterised by a glass façade with colourful movable shutters and symbolic Peruvian designs (2, 3, 6). It has green walls on the three main fronts, four daylight fronts and a roof garden (2). The architect, Jean Nouvel, worked together with ARVE Peru on the overall landscape plans for the Real Dos tower (1, 3).
This is part of the façade remodelling project of the Camino Real Towers in the Real Business Centre, led by the real estate company Grupo Centenario (1, 2, 3, 4, 5, 6). This overarching Project has sought to develop 4,475 m2 of vertical gardens and roof gardens, which have a technified irrigation system to generate efficiencies in water use, meeting the plants' water requirements in the different seasons of the year. Their implementation helps to filter CO2 and renew the O2 in the office complex.
The ARVE group describes these actions as conducive to creating thermal barriers and sound insulation, a better environment for rest, work and entertainment and increasing property value (7)

The Metropolitan Linear Park is a project initiated by the national government of Bolivia, funded by the Inter-American Development Bank (IDB) (1-8). The proposed park will be located along a disused railway corridor between the cities of La Paz and El Alto, spanning 18.2 km (8, p. 8). The project involves the construction of a linear park, divided into five sections, each with distinct objectives, uses, and designs (8, p. 9). This large-scale initiative aims to improve access to public spaces in La Paz and El Alto, enhance connectivity between the two cities, protect surrounding biodiversity and natural spaces, and strengthen resilience to and mitigate the effects of climate change (3 & 8, pp. 11-12).
To achieve these goals, the project design includes outdoor sports and recreational facilities, pedestrian and cycling circuits, as well as the restoration of parks, squares, and public spaces adjacent to the park corridor (8, p. 9). Some features include balcony corridors, flower and food-producing urban gardens, and viewpoints (5). The project also plans for the re-vegetation of the area with native species and aims to stop the environmental degradation of surrounding natural environments, such as the Pura Pura forest, which has been suffering from ongoing deforestation and waste dumping (8, p. 9). These efforts are expected to increase and support biodiversity in the area (7 & 8, p. 12).
Additionally, the project emphasizes social inclusion, with policies designed to incorporate women, indigenous populations, and persons with disabilities (8, pp. 7-8). The park is intended to raise awareness about climate change and biodiversity, ultimately improving the quality of life and health of nearby residents and the citizens of La Paz and El Alto (8, p. 13).

Alexandria is one of the vulnerable cities facing climate change (1). From rising sea levels, pollution, extreme rise and fall in temperature and the urban heat island effect, Alexandria is battling significant challenges (1). The city is also worldly renowned for it beaches and gardens that act as the lungs through which the city breathes, and are considered a haven for its people (1). Unfortunately, in the last ten years, there has been a decrease in parks and green areas, which is a cause for concern (1). This shrinkage comes at the expense of urban expansion and the establishment of Commercial and profitable projects, which is a challenge facing the environmental balance and cultural heritage of the city (1). To address the nature of the challenges and climate changes and their effects in Egypt, the president launched the "The 100 Million Trees Initiative" was brought into action in 2022 as part of the Egypt 2030 Vision (2-3). The campaign is meant to double the per capita share of green spaces across the country, improve air quality and people’s health, and reduce greenhouse gases. It will also aim to recoup economic benefits from the trees, including wood and olive oil (3). As part of this initiative, the governor of Alexandria was tasked with taking care of the green spaces and improving the aesthetic and civilizational level, within the scope of Alexandria's neighborhoods and centers (4). In 2023, the gardens department carried out the planting of 812 trees and shrubs of various types within the scope of Al-Muntazah 2 Neighborhood during Week 25 to continue the work of the presidential initiative to plant 100 million trees in the governorate's neighborhoods (4).