Integrated indoor hygiene concept in a kindergarten living lab: effects on microbial load and infection-related absenteeism

Introduction Effective infection prevention and control (IPC) in buildings requires integrated strategies addressing air, surfaces, and water systems. Methods This study evaluated the impact of an Indoor Hygiene Concept (IHC) on microbial contamination and infection-related absenteeism in a real-world kindergarten setting. A Living Lab intervention was conducted, where one unit implemented antimicrobial coatings, antimicrobial blue light technology, and a portable air purifier, while a comparable control unit remained unchanged. Environmental sampling of high-touch surfaces (n = 368 per unit), monitoring of infection-related absences among children aged 3–5 years and staff, and continuous indoor air quality assessment were performed between 2023 and 2025. Results Baseline environmental and hygiene conditions were comparable between units. Antimicrobial coatings reduced mean surface microbial load (9.4 vs. 15.9 CFU/cm 2 ), although median values were similar, indicating very limited effects under high baseline hygiene conditions. The intervention unit showed a consistent but not statistically significant reduction in infection-related absenteeism (19% in staff and 12% in children). Discussion These results suggest that integrated indoor hygiene solutions may support infection control in real-world settings. More extensive studies, including larger human study populations, and viral measurements are needed to confirm these preliminary observations and evaluate long-term sustainability.