Impact of urban green areas on air quality: An integrated analysis in the metropolitan area of São Paulo

Abstract

Cities must be prepared to improve the quality of life, including exposure to air pollutants, for their residents as urban populations continue to grow. Green infrastructure and green areas have proven increasingly important in tackling this challenge. This study examined the relationship between urban green spaces and air pollution in the São Paulo Metropolitan Area. Using PM₁₀ and PM_2.5 as indicators of atmospheric pollutants and NDVI and NDBI to evaluate green areas and building density, statistical tools such as cluster analysis and Sen's Slope test were applied, complemented by visual analyses with temporal heat maps. The results indicated a general reduction in PM_2.5 and PM₁₀ concentrations from 2014 to 2023, with NDVI increasing until 2021 and then decreasing, possibly due to real estate speculation. Regions with higher NDVI showed 50 % lower PM concentrations compared with industrial and high-traffic areas. The Sen's Slope analysis outlined the influence of tree-planting public policies on reducing pollutant levels. These findings the ongoing importance of research on the interaction between green areas and urban air quality to inform decision-makers.