Anthropogenic particulate pollution is a common urban problem. Generated by the slow breakdown of tyres and mechanical parts, carbon fuel combustion, construction projects, encroaching wildfires and desertification, and seasonal profusions of pollen, a constellation of dust gathers in the pores of the city.

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Plant foliage is the biggest natural particulate matter sink on Earth. Tree planting is therefore one of the most effective methods used to combat particulate pollution concentrations in urban environments. Leaves can trap particulates in several ways, from accumulation on hair-like trichromes to capture through stomatal pores. Bark is also absorbative through its lenticels, raised fissures that facilitate gas exchange between a tree’s internal tissue and the atmosphere. Plants breath in dust so we don’t have to. 

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Of course, the scope of urban greening is limited. Vegetation requires space, light, water, earth – things often at a premium in cities. To find a complementary strategy, we collaborated with a team of environmental engineers at the Department of Mechanical and Industrial Engineering at the University of Brescia – with partners at the European Commission, the Italcementi–Heidelbergcement Group, and INSTM Trieste – to advance the development of SUNSPACE (SUstaiNable materials Synthesized from by-Products and Alginates for Clean air and better Environment). First published in Frontiers in Chemistry in 2018, SUNSPACE is a new material designed to reduce anthropogenic pollution in the city that can be applied to walls and roofs as simply as a coat of paint. Resulting from the reaction of a few easily sourced ingredients, its surface topology mimics that of leaves, allowing it to passively capture particulates.