Urban green spaces and air quality in the State of São Paulo: a spatiotemporal analysis of the metropolitan regions of Campinas and Piracicaba

Abstract

Air pollution remains a major environmental and public-health concern, especially in urban and peri-urban regions where emissions, land use, and seasonal meteorology interact. Although GI is often proposed as a strategy to improve air quality, its effects are highly context-dependent and difficult to isolate. This study examined the association between vegetation greenness, represented by NDVI, and monthly concentrations of particulate matter (PM10 and PM2.5), and NO2 in the MRC and MRP, São Paulo State, Brazil, from 2019 to 2025. Pollutant and meteorological data were obtained from CETESB AQMS, and NDVI was derived from Sentinel-2 imagery in Google Earth Engine within 100, 250, 500, and 1000 m buffers around each AQMS. Associations were assessed using Spearman correlations, LOWESS smoothing, Mann–Whitney U tests, and multiple linear regression models adjusted for meteorological variables and temporal fixed effects. NDVI was predominantly negatively correlated with pollutant concentrations, with coefficients ranging from − 0.24 to − 0.83 for PM10,  − 0.17 to − 0.82 for PM2.5, and − 0.31 to − 0.75 for NO2. Seasonal patterns were evident, with higher pollutant concentrations and lower NDVI values during the dry season. In adjusted regression models, significant negative NDVI associations were mainly observed in MRP, particularly for PM10 at 100–250 m, PM2.5 at 100–500 m, and NO2 at 100–500 m, whereas most associations in MRC were non-significant. PM10 and NO2 concentrations were significantly higher in MRP than in MRC, whereas PM2.5 showed no significant regional difference. These findings suggest that urban greenness is associated with air quality patterns in a context-dependent manner, reinforcing the need to account for spatial scale, seasonality, and local land use conditions in GI planning.