Fog-in-Place (FIP): Engineering, Microbiological Validation and Risk-Based Deployment of Automated Aerosol Treatments

Abstract

Fog-in-Place (FIP) denotes an operational approach in which a treatment medium is dispersed into an enclosed or semi-enclosed facility as a fog or aerosol, with the objective of reaching distributed surfaces while limiting manual point-by-point application. FIP is a process description, not an internationally standardized assurance of efficacy, and it encompasses fundamentally different generation technologies, including cold atomization and thermal fogging. This review assesses aerosol formation, transport, deposition, microbial inactivation, validation strategies and European regulatory classification. It focuses on bacteria, yeasts, filamentous fungi and spores, with biofilm-associated organisms considered as a distinct challenge. A transparent synthetic deposition model illustrates how surface orientation and exposure alter coverage under illustrative assumptions, without representing field efficacy. The most defensible role for FIP is as a risk-assessed adjunct to validated cleaning and hygiene systems, evaluated as a complete process consisting of equipment, treatment medium, operating conditions and facility geometry.