AIRFRESH: Air pollution removal by urban forests for a better human well-being


The demonstration actions are implemented at 2 front-runner cities among the most influenced by air pollution in Europe, with administrations interested in demonstrating urban forests benefits: Aix-en-Provence (France) and Florence (Italy).

Action B1 - New Urban Forest Areas: planting, maintenance and data collection

Two co-design workshops will be organized from October 2020 to July 2021. For workshop#1, the local stakeholders will inform researchers of their expectations to define a list of parameters to be included for plant ranking. Based on Sicard et al (2018), we will rank the plant species according to e.g. their characteristics; effectiveness in removing air pollutants; tolerance to drought, pest and disease ... During workshop#2, a list of 10 suitable plant species (i.e. adapted to local conditions, and 10 species “not recommended” will be delivered to municipalities.

As large-scale reforestation is not feasible within a project, one test area will be implemented in both cities for tree planting in 2022 (each area: 400 fast-growing trees, mix of species, > 2 m tall, spacing 5x5m, equivalent to 1ha).

Measurements campaigns (winter-summer) of air pollutants concentrations and air temperature/relative humidity will be carried out in and around the tree-covered area, above and below the canopy, before (2021) and after tree planting (2023-2024).

Action B2 - Estimation and Mapping of Ecosystem Services at city scale

To assess the air pollutants removal capacity, either direct measurements are used at local scale (Action B1) or dry deposition models at larger scale.

Urban tree distribution and classification - The urban trees characteristics (e.g. distribution, Leaf Area Index, species) are derived from Pleiades images (high spatial resolution: 50cm) by spectral and textural classification.

Quantification of environmental benefits - The air pollutant dry deposition, including stomatal uptake and non-stomatal deposition, as well as the carbon stock and the cooling effect by urban forests will be quantified and mapped at city scale before the tree planting activities (year 2021) and after reforestation (year 2023).

Action B3 - Scaling-up and Replication

From January 2023, the core activities will be upscaled from city to conurbation scale. The annual removal of PM2.5, PM10, NO2, CO2 and O3 as well as the carbon stock by each forest category will be quantified and mapped at conurbation scale for the year 2023.

From January 2024, partners will start to collect the data needed (e.g. air quality, tree distribution, local settings) for replication in Zagreb (Croatia). By November 2024, the annual removal of air pollution by forest category will be quantified and mapped over Zagreb. The main aim is to verify possible shortcomings and correct them before the end of AIRFRESH and before replication in Bucharest beyond 2024.

Action B4 - Knowledge Transfer to city planners

Findings will be summarized as guidelines of good practices (tree planting, maintenance), context-adapted and prepared with local stakeholders, i.e. effective measures for sustainable air pollution and climate change governance in cities (local urban masterplan).

The best practice guidelines for managers and local decision-makers, to maximize the benefits from urban forests, will be transferred during 1-day meetings and put into practice in at least 10 cities in France, Italy, Romania and Lithuania beyond 2024.

Action C1 - Monitoring and Quantification of Environmental Impacts

We will evaluate the benefits of both test areas in terms of savings in CO2 equivalents as well as of air quality improvement, climate benefits (reduction of air temperature) and ecological benefits (Singapore Index on Cities’ Biodiversity: biodiversity enhancement, pollinators, greenness). By concrete actions for air pollution mitigation, CO2 sequestration and air temperature reduction, AIRFRESH will facilitate compliance with air quality limit and EU Environmental policies (e.g. Directive 2016/2284/EU, EU Biodiversity Strategy for 2030, EU Urban Agenda) and will contribute to reach some UN-SDGs for the 2030 Agenda.

Action C2 - Monitoring and Quantification of Socio-Economic Impacts

To date, no study focused on benefits of air pollution reduction on citizens' health and well-being due to the implementation of urban forests.

The health benefits (AirQ+ model) in terms of changes in life expectancy and number of cases (mortality and morbidity) for respiratory and cardio-vascular diseases due to short-term changes in air pollution will be estimated before and after reforestation. We will also calculate the direct economic impact of the urban forest implementation and maintenance as well as the monetary benefits of “avoided” premature deaths and hospital admissions, and gained life years, attributed to the reduction of air pollution after reforestation. We will assess the perceived quality of and satisfaction with the urban forest. Two questionnaires will be drafted for the pre- and post-implementation analysis.

Action D1 - Dissemination planning and execution

Synthesize key findings generated by AIRFRESH. Prepare and conduct outreach activities, help practitioners and decision makers to make use of the new knowledge. Dissemination methods are website, social media, publications, the notice boards, Layman’s report, workshops, public events, educational activities. Reforested areas will serve for didactic visits.

Education of citizens about the good practices (e.g. transportation, diet) for a cleaner air in cities and for a better citizens’ well-being by displaying A3 boards in doctor’s waiting rooms in Aix-en-Provence and Florence from January 2021.

In 2022, we will organize a Tree Planting ceremony to draw the citizen's attention to the importance of nature, trees and biodiversity in the city. Furthermore, it will further expand and support the godfathering of a tree. By 2024, 100 trees will be planted by citizens in private gardens.

Action D2 - Science-Policy-Stakeholder interaction

A major challenge for national and European policymakers is that scientific research results are not always incorporated into policy. Face-to-face oriented meetings (1-day meeting) with stakeholders will be organized as a key contribution to improving the science-policy interface. Representatives of local-to-regional authorities and main stakeholders for replication abroad are involved. Most important stakeholders are Municipalities, Regional Councils, Expert Panel on Clean Air in Cities, International Cooperative Programme (ICP-Vegetation), European Commission (DG REGIO, DG ENV), International Union of Forest Research Organizations (IUFRO).