Separating the In from the Out

More than the people or the equipment, the one element virtually guaranteed to contact food during processing is the air inside the plant. Indoor air can become the vector that delivers contaminants to food and food contact surfaces. HVAC systems are critical control points (CCPs) in ensuring that food production remains safe from pathogens, allergens and other airborne contaminants.

In-plant air quality must be managed as part of the HACCP program. As FDA advises in its 21 dFR 110.20 document, the food processing plant and facilities shall “locate and operate fans and other air-blowing equipment in a manner that minimizes the potential for contaminating food, food-packaging materials, and food-contact surfaces.”

Best practices incorporate a consistent program to test and monitor interior air quality, including regular testing for levels of airborne particulates. Airborne particles may include allergens or other food contaminants, such as dust from deteriorating lead paint, and particles that can carry disease-causing microorganisms.

Regular air quality testing, including the use of hand-held particle counters to monitor particulate levels, can help ensure that changing conditions are detected early and emerging problems are dealt with before production is disrupted or, even worse, contaminated product reaches consumers.

Keeping the Outside Out

Sanitary design to control airborne hazards starts outside of the facility. Any contaminants found outside of the plant, such as insects, rodents, birds and windborne microbes contained on dust particles, are liable to enter. Outside air may contain high counts of particles carrying microbes, and particle concentrations indoors tend to “track” those outside.

The FDA identifies maintenance of the plant and grounds (trimming weeds, maintaining roads and parking lots and providing adequate drainage) as an important factor in preventing contamination. Best practices in food plant operation prevent the intrusion of outside air. Doors and windows must be kept closed and loading doors must be closed or, during operations, sealed to limit the entry of contaminated air, insects, birds and rodents.

In addition, air inside the plant should be maintained at a higher pressure than outside. The HVAC system is managed to draw in some outside air, condition and filter it and pump the filtered air into the facility to maintain positive pressure. Inside air will prevent contaminated outside air from entering through any gaps, or when doors or windows are opened.

Best practices in sanitary design and operation of HVAC systems emphasize maintaining positive air pressure, air filtration to remove particulates, and maintaining the system to prevent microorganism growth.

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