Fogging Applications (QAC, PAA) in Food Processing Plants

Fogging is used primarily for disinfecting airspace in food processing areas. As microorganisms can be carried in the air zone and transferred to food contact surfaces. It may be important, particularly in high-care environments, to disinfect the airspace.?Aerial disinfection should only be conducted after all cleaning and disinfection of food contact surfaces has been finished. It should never be used as an alternative to surface disinfection.

It can be carried out using a gas, such as ozone, or more usually with a 1- 3% disinfectant solution via a compressed air fogging unit. The liquid foggers work by supersaturating the atmosphere with a disinfectant fog. The area they can cover will vary dependent on the fogger.?The disinfectant fog in the atmosphere helps to bring down any microorganisms onto the disinfected surfaces.??

Although fogging is intended for the disinfection of airspace, some research has been performed to determine if it can be used as a sustainable method for terminal disinfection of all critical surfaces in a food processing area. This method is called electrostatic fogging where surfaces are electrically charged to attract the disinfectant droplets to the surface. If this approach could be made to work, then considerable benefits may be brought to the cleaning and disinfection of food premises.

Why fogging?

There may be a need to fog in certain food processes to ensure a reduction in airborne microorganisms that may have come from low-risk areas, people, and fabric of the building or as aerosols from the cleaning process. Microbiological sampling as part of the factory hygiene procedure should know where there is a need for fogging.

Where should fogging take place?

Fogging is mostly carried out in high-care processing environments, particularly cheese manufacturing, sandwich, ready-to-eat meals, cooked meats etc. It is estimated that more than 50% of frozen food manufacturers conduct this method of disinfection in conjunction with routine cleaning and disinfection plan.

How is fogging performed??

Fogging is generally done by using either a static, purpose-built system in an area of a facility with strategically placed nozzles or most commonly by using a mobile unit.

A built-in system will typically be used for production areas larger than 250m3 with mobile units usually being employed for areas smaller than this number. The disinfectant fog is generated through the system or the mobile unit into the local atmosphere by charging the unit with compressed air and forcing the disinfectant solution through the dedicated nozzles at a 1-3% solution.?

The fogging unit should be left to run its course which takes approximately 30 minutes to complete. No personnel should be in the area which is being fogged as the fog will cause breathing difficulties. It may take up to 1 hour after the fogger has emptied before access to the area is possible.

During fogging, it is always recommended that sensitive equipment such as metal detectors, check weighers, printers, etc should be covered with clean polythene (or removed from the area to be fogged if possible) to prevent liquid ingress. Polythene should then be removed after the process and the equipment wiped over.?

How often should fogging be conducted?

Dependent on the nature of the process and from the results of micro sampling and air plate testing, aerial disinfection will typically take place on a weekly basis in a high-care food processing area. Items such as blast chills and blast freezers may need to be fogged on a daily basis, dependent on the nature of the product being chilled or frozen, although in some cases where production is required to be running 20 hours per day 6/7 days a week, fogging is not always possible.

What type of disinfectant is used for fogging?

Generally a formulated and independently tested QAC-based disinfectant will be used for fogging at a 1-3% solution. However, if the site has a problem with spores, a QAC disinfectant will not be as effective. An option would be to use a peracetic-based disinfectant at 1% solution. It is always recommended that after fogging all food contact surfaces are rinsed with low-pressure, clean water to remove disinfectant residues before being re-disinfected with a terminal disinfectant.

What health and safety precautions do I need to take?

Health and regulations authorities apply to the use of disinfectants in the workplace, these regulations require employers to carry out a risk assessment. The assessment should be completed by a person who understands these regulations, has the ability and authority to attain the necessary information, and make the correct decisions about the risks and precautions required during fogging operations.

Risks are determined by the following steps:

? Check the Safety Data & Product Information Sheets. Consider the use of the least hazardous product that will be effective. Disinfectants used for fogging should not have a detrimental effect on the materials of construction in the area to be fogged.

? Identify procedures for all jobs and activities such as dilution of disinfectants, filling the fogging machine, tasks during fogging and settling periods, re-entry to the fogged area, maintenance of fogging equipment, and emergency procedures.

? Identify who may be exposed.

? Consider the routes of exposure such as inhalation/skin contact/ingestion.?

Important Note: Fogging should only be used after a thorough cleaning and disinfection procedure has taken place and is not a substitute. Fogging has been found to be ineffective at disinfecting underside and vertical surfaces as well as dismantled equipment and should be used as an additional safeguard only.??

References

1- University of Florida

2- Food and Agriculture Organization (FAO)

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