Human-independent hygiene solutions in built environments: framework for costs and benefits

Infectious diseases continue to impose substantial health and economic burdens on societies, and the built environment has become an increasingly important target for infection prevention and control. In response, a growing range of human-independent indoor hygiene solutions has been developed, including antimicrobial surfaces and coatings, touchless fixtures, air cleaning devices, and antimicrobial lighting. These interventions are attractive because, unlike conventional hygiene measures, they do not rely primarily on user compliance. However, the evidence base for these technologies remains uneven. Most studies focus on reductions in microbial contamination, whereas far fewer assess outcomes that are more meaningful for decision-making, such as infection incidence, absenteeism, or healthcare utilization. From a public health and built-environment perspective, this distinction is crucial: a lower microbial burden does not necessarily translate into reduced morbidity. In this Perspective, we propose a structured framework for evaluating human-independent indoor hygiene solutions that integrates financial, health-related, and environmental costs alongside potential benefits. Assessments should consider not only health gains but also financial costs, unintended health effects, environmental burdens, and opportunity costs. A nursing home pilot is used as an illustrative example of how these cost categories emerge in practice. Current evidence suggests that consistent morbidity reduction has not yet been demonstrated for most human-independent indoor hygiene solutions. We therefore argue that their evaluation and implementation should move beyond proxy microbiological indicators and adopt a structured, context-sensitive approach. Until stronger evidence is available, their implementation should remain cautious and selective.