This study critically examines the impact of indoor air quality (IAQ) on occupant health in two critical care units (ICUs) at Jason Sendwe Hospital (JSH) and General Carrier de Mine Hospital (GCMH) within the Southern DRC metropolitan area, focusing on their impact on occupant health and well-being. Utilizing a mixed methods approach that includes health questionnaires, continuous environmental monitoring (monitoring CO2, VOCs, PM2.5, PM10, temperature, and relative humidity), and computational fluid dynamics (CFD) analysis, this research aims to identify correlations between environmental factors and the health of hospital staff and patients. The investigation was conducted across both the rainy and dry seasons, revealing significant seasonal variations in IEQ parameters and exploring the incidence of symptoms commonly associated with sick building syndrome among hospital staff. Higher CO2, VOCs, and particulate matter levels during the dry season indicated the inadequacy of current ventilation strategies to maintain optimal air quality. This study proposes the implementation of air filtration and purification systems and the refurbishment of natural ventilation systems as effective measures to improve IAQ. Additionally, alternative ventilation strategies, including occupancy reduction and the integration of supply and exhaust ventilation, were explored to address the challenges of inadequate ventilation. The findings reveal the urgent need for hospitals to adopt ventilation strategies that ensure the health and well-being of occupants, highlighting the importance of continuous IAQ monitoring, community engagement, and the integration of advanced ventilation technologies in healthcare settings. This comprehensive exploration offers valuable insights for improving ventilation in ICUs, contributing to creating healthier indoor environments in hospital settings, especially in regions facing unique environmental challenges.