Spatiotemporal Variability of Indoor CO2 and PM2.5 in a Multifunctional, University-Affiliated Healthcare Facility

Indoor air quality (IAQ) in healthcare facilities is increasingly recognized as a key determinant of occupant health, comfort, and operational performance. Owing to heterogeneous space functions, varying occupancy patterns, and dynamic operational conditions, IAQ parameters may exhibit marked spatial and temporal variability within the same facility. University-affiliated healthcare buildings, where clinical services coexist with academic and administrative activities, represent particularly complex indoor environments that remain relatively underexplored in the current IAQ literature. This study examines the spatiotemporal variability of indoor carbon dioxide (CO2) and fine particulate matter (PM2.5) concentrations across four representative functional zones within a university-affiliated healthcare facility, including a patient waiting room, an academic office, an administrative office, and a restorative dental clinic. Continuous, long-term monitoring was conducted over a multi-month period to capture both spatial differences and diurnal dynamics under real operational conditions. Daily mean CO2 concentrations varied across functional zones, ranging from approximately 540 to 620 ppm, with higher levels generally observed in spaces with sustained occupancy and limited ventilation. Daily mean PM2.5 concentrations ranged from approximately 13 to 18 µg/m3, with greater variability detected in zones associated with intermittent activities and procedural sources. Unlike many IAQ studies focusing on single departments or short-term campaigns, this multi-zone, long-term assessment within a shared building infrastructure enables direct comparison of functional spaces and identification of time-specific exposure patterns. Overall, the findings highlight that IAQ conditions within healthcare facilities are shaped by both space function and temporal factors, even under shared ventilation infrastructure. The results emphasize the value of zone-specific and time-resolved IAQ assessment approaches and provide evidence-based insights to support targeted ventilation strategies, activity-aware operational controls, and improved indoor environmental management in healthcare settings.