A new study shows that increasing urban greenery by just 5% could prevent nearly 5,000 premature deaths annually, underscoring the vital role of trees in public health.
Trees and public health benefits
Urban greenery has a direct impact on people’s health and helps lower mortality linked to pollution. An international study carried out under the European AIRFRESH project, with contributions from ENEA researchers, found that trees reduce air pollutants.
According to the study Effect of tree canopy cover on air pollution-related mortality in European cities: an integrated approach, published in The Lancet Planetary Health, planting 5% more trees in cities could prevent around 5,000 premature deaths each year.
The research combined environmental and health data across Europe from 2000 to 2019 to measure how tree canopy cover affects pollution levels and mortality caused by fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ground-level ozone (O3). Where urban greenery increased, pollution-related deaths decreased.
The 3-30-300 strategy
Alessandra De Marco, head of the Laboratory on Impacts in Territories and Developing Countries and project coordinator for ENEA, explained: “By 2050, about 80% of Europe’s population is expected to live in urban areas, making these issues increasingly urgent. Planting more trees in cities brings multiple benefits: improved air quality, reduced summer heat island effects, preserved biodiversity, and, most importantly, improved public well-being.”
The United Nations Economic Commission for Europe (UNECE) recommends the 3-30-300 strategy: 3 trees visible from every home, school, or workplace, 30% canopy cover in each neighborhood, and no more than 300 meters between a residence and a public green space.
Findings across 744 european cities
The study analyzed 744 urban centers with more than 50,000 residents in 36 countries. Between 2000 and 2019, average tree cover rose by 0.76 percentage points, with 73.5% of cities seeing an increase in greenery, while mortality rates dropped by an average of 3.4%.
In 2019, about 25% of Europe’s urban population lived in cities with more than 30% tree cover. In Italy, only Naples reached 32%, while Milan and Rome had just 9% and 24%, respectively.
The researchers estimated that every 5% increase in canopy cover could improve annual average air quality by 2.8% for PM2.5, 1.4% for NO2, and 1.2% for ozone. It could also prevent 4,727 premature deaths annually across the studied cities. Achieving 30% tree cover could prevent up to 12,000 deaths every year.
EU goal of 3 billion trees by 2030
The EU Biodiversity Strategy requires member states to plant at least 3 billion trees by 2030, a target aimed at significantly expanding urban greenery.
To reach this goal, planting programs must include not only public spaces but also private areas such as residential courtyards and peri-urban zones. Urban planners should integrate green infrastructure tailored to local contexts, combined with emission reduction policies and complementary measures like cooling corridors or green roofs. These steps would maximize public health benefits, improve quality of life, and make cities more sustainable and resilient to climate change.
Mitigating heat waves with urban greenery
The research highlights the therapeutic role of urban greenery, showing its ability to make cities healthier, more livable, and more sustainable. Green areas also help mitigate heat waves, which caused 62,000 deaths across Europe in the summer of 2022.
While this therapeutic aspect has long been overlooked, evidence now confirms that planning urban green spaces and tackling air pollution are powerful tools for improving public health.
