How well did the evaporative passive cooling blanket preserve fresh produce in Kenya, Uganda and Nigeria?

• Passive cooling blanket (PCB) reduced temperature by a maximum of up to 20 °C. • PCB shows consistent performance across diverse climatic conditions and crop types, maintaining high humidity and stable temperatures. • PCB extended fresh produce shelf life and significantly reduced postharvest losses. • PCB reduced vendor tomato losses by approximately 92% in Uganda. • 97% of Kenyan farmers showed interest in adopting the PCB for improved storage. This study evaluates the effectiveness of evaporative passive cooling blankets (PCBs) in reducing postharvest losses and extending the shelf life of fruits and vegetables in Kenya, Uganda, and Nigeria. Using locally available natural materials such as sawdust and charcoal, PCBs were deployed under diverse climatic conditions to assess their capacity for temperature reduction and humidity control. In Kenya, PCBs achieved temperature reductions of up to 10 °C and maintained relative humidity near 95 %, reducing postharvest losses of vegetables by up to 45 % and extending shelf life by 3–4 days. In Uganda, PCB application along the local tomato supply chain lowered average air temperatures by up to 2 °C, with peak reductions of up to 20 °C. This intervention extended tomato shelf life by 2 days and improved market outcomes, although performance was moderated by rainy-season conditions. In Nigeria, PCBs reduced average air temperature by 5 °C, increased relative humidity by 25 %, and decreased tomato weight loss and rot by 32 % and 20 %, respectively. Overall, the use of PCBs reduced postharvest losses by approximately 30 % across the three countries. These findings demonstrate a scalable, low-cost, electricity-free cooling solution suitable for smallholder farmers in Sub-Saharan Africa. By validating PCB performance under real field conditions, this study highlights the potential of passive evaporative cooling technologies to enhance food preservation, reduce waste, and improve food security in resource-limited settings.