Thermal Comfort, Ventilation, and Mosquito-Borne Disease Risk: A Preliminary Field Study of New Hospitals in Zanzibar, Tanzania

This field study investigated the thermal comfort and ventilation in four newly constructed district hospitals on Unguja island, Zanzibar, and their potential impact on mosquito-borne disease (MBD) transmission. The research was conducted over a 48-day period, measuring air temperature, humidity, CO2 levels and door opening frequency in various hospital areas, including wards, office and clinic, and waiting spaces. Thermal comfort was assessed using the Predicted Percentage Dissatisfied (PPD) index. The study found that most spaces failed to meet ASHRAE 55 thermal comfort recommendations, with ward areas experiencing the poorest conditions. CO2 levels frequently exceeded 530 ppm, the estimated threshold for mosquito detection, particularly in ward spaces during night hours. The research also revealed a complex interplay between building design, thermal comfort, and potential MBD transmission risk. Ward spaces consistently showed higher temperatures, greater PPD values, and higher CO2 levels compared to waiting areas. These conditions, coupled with increased door opening during night hours, could potentially increase the risk of MBD transmission. Air-conditioned spaces, while sometimes achieving better thermal comfort, often had higher CO2 levels due to poor ventilation. The study suggests that passive design strategies, such as improved shading and natural ventilation, could be effective and sustainable solutions for enhancing thermal comfort and reducing MBD transmission risk. This research highlights the importance of considering thermal comfort and ventilation in healthcare facility design, particularly in regions with high MBD prevalence. The findings have implications for future healthcare infrastructure projects in Sub-Saharan Africa, which will require the construction and renovation of space for 2.5 million additional beds by 2030.