Abstract
Rapid urbanisation in tropical megacities intensifies critical environmental stressors, including urban overheating, particulate air pollution (PM2.5 and black carbon (BC)), and noise. Green-Blue-Grey Infrastructure (GBGI) offers a promising nature-based solution, yet major knowledge gaps exist regarding its empirical, multifunctional performance and diurnal dynamics in complex tropical settings. This study quantifies how vegetation in a large urban park (Ibirapuera Park, São Paulo) moderates microclimate, improves air quality, and attenuates noise, while assessing the influence of canopy structure and spatial location on these benefits.
A comprehensive mixed-method approach was employed during a 15-day intensive field campaign. High-resolution spatiotemporal data on PM2.5, BC, carbon dioxide (CO2), noise, and meteorological parameters were collected through a combination of stationary monitoring at nine ecologically distinct sites and mobile transect monitoring across an urban-park gradient. These observations were complemented by thermal imagery and sky view factor (SVF) analysis.
The park delivered substantial and dynamic environmental benefits. Dense vegetation reduced PM2.5 and BC by up to 40%, with mobile gradients of 0.07 and 0.03 µg m⁻3 per 100 m toward the park core, respectively. Cooling averaged 1–2 °C, strengthening to 0.2 °C per 100 m outward in afternoons. A distinct temporal duality emerged: peak cooling occurred in the afternoon, while the strongest air quality improvements occurred in the morning before dense canopy began retaining pollutants. Noise attenuation was modest (∼6 dB), with reductions of 0.29 dB and 0.25 dB per 100 m in morning and afternoon transects.
Overall, the park functions as a multifunctional environmental regulator, with benefits shaped by vegetation density, spatial configuration, and time of day. Effective GBGI planning in tropical megacities should prioritise deep vegetative cores (≥250–300 m from major roads), multi-tiered buffers along traffic corridors, and dense canopy structures (SVF < 0.4). Integrating SVF into zoning and expanding networked green corridors can extend these co-benefits, strengthening climate resilience, public health, and urban liveability.