Which urban trees retained the most PM10 dust in Perugia?

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Reducing air pollution is a crucial challenge in urban areas, and urban green infrastructure could play a pivotal role. Previous research has examined how green infrastructure’s species and layout affect pollution reduction, as well as where to locate new infrastructure to increase overall ecosystem services. But studies are lacking to help planners and designers choose where and what to implement based on species-specific vegetation performance and differing demand for ecosystem services across city areas.

The researchers used tree cadastre data from Perugia, a medium-sized city in central Italy, and Gmaps traffic open-layers to spatially analyze urban trees’ PM10 dust retention and PM10 produced by vehicle emissions, respectively. Their method maps the balance between demand, represented by traffic-polluted sites, and supply, represented by trees’ PM10 retention, to support local decisions on new green infrastructure locations and species choices. The analysis covered 6,710 urban trees across 42.62 km², with a linear road density of 15 km/km².

The resulting optimal species for reducing PM10 were Platanus hybrida Mill. ex Münchh, Celtis australis L., Ulmus carpinifolia L., Pinus pinaster Aiton, Quercus ilex L., Quercus robur L., and Tilia cordata Mill., with respective median retention values of 219.62, 181.47, 166.67, 154.66, 143.90, 118.61, and 118.04 g per tree per year.

The paper presents a first contribution toward GIS-based tools that vary recommended locations and species for new green infrastructure according to the ecosystem service demanded. The authors call on urban planners to dynamically use and integrate multiple tools, including this one, to seek complex solutions that can increase the sustainability of urban systems.