What is “fogging” in the context of disinfection, and what are its features and applications?
Fogging is a method employed to disperse liquid disinfectants into very fine droplets, forming an aerosol or mist. Common disinfectants used in this process include hydrogen peroxide, peracetic acid, and quaternary ammonium compounds. The droplet sizes typically range between 5 to 30 microns, while certain "dry fog" formulations can achieve sizes below 5 microns, however these too remain as droplets. Upon dispersion, the droplets initially suspend in the air and then settling onto various surfaces.
The implementation of fogging methods is generally simple and requires minimal operational training, making it suitable for a variety of general facilities such as offices, educational institutions, food processing centers, warehouses, and public transportation systems. In these non-critical environments, the absolute eradication of contaminants is not paramount, but rapid turnover is prioritized, fogging serves as an effective option.
However, the applicability of the fogging method in critical environments, including cleanrooms, BSL-3/4 laboratories, hospital isolation units and pharmaceutical manufacturing settings, is more complex. A thorough understanding of fogging systems is required to make appropriate decisions in these contexts.
Due to the size of the droplets, the airborne diffusion achieved through fogging is limited, restricting the method's penetration into narrow openings and cracks. The dispersal of disinfectants typically occurs in a singular direction, resulting in potential coverage gaps in shadowed areas or those hidden surfaces obstructed from direct line-of-sight. The effective reach of disinfectants is significantly influenced by the airflow patterns within the environment. Consequently, when considering fogging for use in critical settings where a guaranteed 6-log reduction with high-level decontamination across all surface areas is necessary, it is essential to focus on log reduction metrics, the coverage and locations of biological indicators and chemical indicators in validation cycles, and the reproducibility of the biocontamination processes to decide the right decontamination method.
Picture of fogging