Assessing Benefits of Green Roofs in Urban Context Quantification of Air-Pollutants Cut Down by Green Roofs and Positive Effects on Population Health Status

OBJECTIVES Densely-built urban areas are affected by high air pollution levels, whose are caused by vehicle traffic, which represent the main emission source into the atmosphere, but also by combustion processes of buildings’ heating. Smog and fine particles are responsible for health problems such as respiratory and cardiovascular diseases, with repercussions mainly on weak population (elderly and children groups). The green, in all its forms, and especially plants are able to absorb these toxic substances by filtering polluted air, releasing oxygen into the atmosphere and, where it is possible, reducing noise pollution. Aim of the research is to quantify the capability of green roofs as an element to reduce air-pollutants in urban contexts, investigating the positive effects on population health status. METHODS The first phase of the study analyses the green areas’ effects of citizenship’s health, through a systematic review of the scientific literature. Subsequently, the research work has been developed a calculation model in order to quantify the pollutants cut down in relation to an increase of green surfaces on the flat roofs of an urban area examined. In conclusion, through the calculation model, it has been estimated benefits of a hypothetical intervention of cover green roofs’ transformation, in a neighborhood of Milano city. RESULTS The project of conversion in green roofs through the application of the tool, according to the percentages defined by the morpho-typological analysis of the buildings examined, could reduce the pollutants up to 18,09 μg/m³ of PM10, 13,56 μg/m³ of PM2.5 and 7,24 μg/m³ of O₃ each year. CONCLUSIONS Considering a large-scale urban redevelopment project, in addition to psychological and perceptive benefits, with positive influences on housing quality and life of population, it should be considerate the benefits of environmental sustainability, such as reducing noise pollution, absorption of electro-smog, microclimate mitigation and fixing fine particles.