Modeling air quality regulation by green infrastructure in a Mediterranean coastal urban area. The removal of PM10 in the metropolitan city of Naples (Italy)

The amelioration of air quality represents one of the most complex challenges that the European Union is facing today. Although a successful strategy to improve air quality should decisively act on pollution sources, Nature-Based Solutions (NBS) may provide a huge contribution to tackle air pollution, while delivering a wide range of Ecosystem Services and enhancing the Natural Capital. In this paper, we analyzed, in both biophysical and monetary terms, the role of the Urban Green Infrastructure (UGI) in improving air quality in the Metropolitan City of Naples (Southern Italy) by implementing an accounting model of PM10 removal. Our findings indicate that about 1,148 Mg of PM10 were annually removed by the UGI, for a monetary value of 36 million euros per year. We also assessed the impact of a devastating wildfire that occurred in 2017 in the study area, which resulted in a loss of PM10 removal of about 97 Mg and led to an estimated monetary loss of 3 million euros per year. The results also showed that PM10 removal efficiency largely varies seasonally and across different functional groups of vegetation, highlighting the role of functional biodiversity in the provision of Ecosystem Services under Mediterranean climate conditions. In conclusion, we maintain that the biophysical and economic assessment of Ecosystem Services can support local managers and policymakers in charge of developing urban planning strategies aimed at ensuring sustainable development and human well-being in metropolitan cities.