Leveraging peri-urban forests to reduce temperature and air pollution-related urban mortality in European cities

Extreme temperatures and poor air quality contribute to premature mortality, increased hospital admissions and higher healthcare costs. As the majority of the world’s population lives in cities, understanding how urban vegetation mitigates temperature and pollution hazards is essential for designing strategies to enhance urban resilience and reduce mortality. However, estimating the health benefits of urban greening is challenging due to the non-linear physical, chemical, and biological processes involved. Here we use a coupled climate-chemistry model to assess the impact of different peri-urban tree planting scenarios on temperature- and pollution-related mortality and their associated costs over three Euro-Mediterranean cities. We find that peri-urban greening primarily allows to reduce mortality from non-optimal temperatures and, to a lesser extent, air pollution, with effectiveness depending on the selected trees species and local meteorological and chemical conditions. This study provides methodological insights to guide urban planners in leveraging nature- based solutions effectively while avoiding adverse health effects from poor tree selection.