Effect of tree canopy cover on air pollution-related mortality in European cities: an integrated approach

Area of Science:

• Environmental Science
• Public Health
• Urban Planning

Background:

• Harmful air pollutants in urban areas include fine particles (PM2.5), nitrogen dioxide (NO2), and tropospheric ozone (O3).
• Urban greening is recognized as a strategy to improve air quality, mitigate climate change, and enhance citizen well-being.
• This study quantifies the impact of tree cover on air pollution and associated mortality in European cities.

Purpose of the Study:

• To estimate changes in tree cover across European urban centers.
• To assess the mortality burden attributable to PM2.5, NO2, and O3 pollution.
• To determine the potential mortality reduction achievable through increased urban tree coverage.

Main Methods:

• Quantitative health impact assessment conducted across 744 European urban centers (population >50,000) in 36 countries.
• Analysis focused on the relationship between mean tree cover, air pollutant levels (PM2.5, NO2, O3), and all-ages mortality.
• City-wide scale analysis performed to estimate effects on air quality and mortality.

Main Results:

• Mean tree coverage increased by 0.76% between 2000-2019, with 73.5% of centers showing increased green cover.
• A 5% increase in tree canopy cover could improve air quality by reducing PM2.5 by 2.8%, NO2 by 1.4%, and O3 by 1.2%.
• In 2019, 25% of the population resided in areas with over 30% tree canopy coverage.

Conclusions:

• Increasing tree canopy cover by 5% could prevent an estimated 4,727 premature deaths annually from air pollution in European urban centers.
• Achieving 30% canopy cover in all cities could potentially prevent 11,974 premature deaths each year.
• Expanding urban tree coverage offers significant public health benefits, contributing to more sustainable, livable, and healthier cities.