Improving habitability in informal settlements in the Global South: Exploring the impact of community urban green infrastructure on outdoor heat stress

Over 1 billion people currently live in informal settlements, which have become the predominant form of urbanisation, especially in the Global South. They are characterised by dense housing with inadequate access to infrastructure and services. Due to fragmented efforts to create and maintain urban green spaces the possibility of improving outdoor thermal conditions is limited. This study investigates the impact of small community parks on outdoor heat stress in José Carlos Mariátegui, an informal hillside settlement in Lima, Peru. A mixed-methods approach was employed, combining ground-based fixed-point measurements and satellite-derived land surface temperature data. Air temperature, humidity, wind speed, and solar radiation were recorded using a weather station on a sun-exposed rooftop and a compact data logger in a nearby shaded park. Spot solar radiation measurements were taken using a portable pyranometer. Satellite thermal imagery from Landsat 8 was processed using QGIS to assess spatial thermal patterns. The Universal Thermal Climate Index was applied to evaluate heat stress under both sun-exposed and shaded conditions. Results showed that the small park reduced average air temperature by 0.5 °C, with peak cooling of 3 °C in the morning hours. However, afternoon warming was observed, likely due to local topography and tree canopy effects. Despite this, shaded areas significantly reduced heat stress exposure—from 60 % to less than 20 % of daytime hours. The study highlights the importance of low-cost, context-sensitive green infrastructure in mitigating heat stress in resource-scarce urban environments. It offers actionable planning insights, essential for protecting public health in marginalised, low-income communities in the Global South.