Cleanroom Technology - Cleaning and Disinfection: Whole room fogging

Cleanroom Technology - Cleaning and Disinfection: Whole room fogging: "Both the pharmaceutical and clinical sectors have been targeted by a range of whole room type decontamination systems, but their practical operation and benefit in the food and drink industry is relatively unknown. The range of techniques is increasing, but those that are commercially available include:

• chemical fogging
• vaporised hydrogen peroxide
• ozone
• chlorine dioxide
• ultraviolet light
• titanium dioxide coating and UV light
• ionisation

Critical factors to address before using these techniques include: identifying areas where the decontamination processes can be applied, any health and safety issues related to using the technique and the practical considerations related to their use in the food processing environment. The level of disinfection that these systems can achieve also needs to be determined, as some may achieve decontamination of all exposed room surfaces, such as ceilings, walls, floors and equipment, while others may include some penetration into equipment to contact indirectly exposed surfaces. They may also provide disinfection of the air in the area being treated.

Chemical fogging: Applying chemical disinfectants to production areas as fogs or mists is a method used routinely in the food industry. The purpose is to create and disperse a disinfectant aerosol to reduce the numbers of airborne micro-organisms and also to apply disinfectant to surfaces that may be difficult to reach. Fogging is achieved using either a static, purpose-built system in a factory area with strategically placed nozzles or, more commonly, a mobile unit.

The equipment supersaturates the atmosphere with a disinfectant fog; the area covered will vary depending on the application system being used. A built-in system will typically be used for production areas >200m3, with mobile units usually being employed for areas <200m3,. Under typical conditions, fogging is carried out for a minimum of 15–30min to enable the fog to disperse and the chemical action to occur. After fogging, an additional period of 45–60min is required to allow the droplets to settle out of the air and onto the surfaces. Electrostatic charging of chemical fogs during aerosolisation can improve the application as the droplets will be attracted to surfaces that are electrically charged."