Eligible reference cities in relation to BVOC-derived O3 pollution

Forested patches play an important ecological role in urbanized landscapes. Nevertheless, in particular conditions, trees can paradoxically worsen air quality through the emission of Biogenic Volatile Organic Compounds (BVOCs) (i.e., isoprenoids), which participate to the reactions forming O together with anthropogenic VOCs and nitrogen oxides (NO X 3 ). Given the continuous increase in urban population, there is the necessity of providing urban managers with sustainability indices in urban areas related to these subtle pollutants. Our study aims to give an overview of reference cities or typology of urban areas suitable for expanding the research on future BVOC-O dynamics. Such "reference" cities represent a sort of study target in order to better model and forecast the future behaviours of BVOC emissions and O 3 pollution. Contexts have been selected on both a regional and global scale in both warmer and colder environments, considering future climate scenarios and gradients from more natural conditions. Urban Heat Island and Urban Cold Island effects were also discussed as representative models for anticipating the impact of climatic change on urban trees. Finally, other factors, such as UV rays, Secondary Organic Aerosols wind transportation and the surrounding biome were considered as interactive drivers of the change. 3