Air Quality
Air Quality
The purpose of an air quality program is to ensure that contaminants in the air (ambient or process air) do not contaminate the product.
In this training we will discuss:
- How air can introduce contaminants
- Properly screening ambient air for foreign materials
- Checking airflow for negative and positive pressure
- Measuring the effectiveness of filtration and ventilation
- Air filtration methods to remove oil, water, and other solids from compressed air
Two types of controls
There are two types of air sources that should be addressed from a food safety standpoint. Both ambient and process air (e.g. compressed air) can introduce contaminants into a product. Ambient air is the atmospheric air in the facility, while process air is a gas of any kind that is used in production and applied directly to the product or product contact surfaces during processing.
Ambient Air
There are many considerations for a facility when it comes to ambient air. Some operations will have stricter regulations for preventing small particles from entering the processing area, including dust and microbiological contaminants. Other operations may be less sensitive and may only need properly screened windows, intake fans, or exhaust fans.
Some factors to consider when designing for ambient air include the following:
- Air flow
- Air filtration
- Air ventilation
- Maintenance of HVAC units
Air Flow
Air flow is important to ensure that air from dirtier areas does not flow into air in cleaner areas. This is done by controlling air pressure. A room with relative positive air pressure will vent air into surrounding rooms with less air pressure. A room with relative negative air pressure pulls air from the surrounding area. Generally, you want positive air pressure in the more sensitive, cleaner areas to ensure that the air moves from clean to dirty, rather than from dirty to clean. A good practice is to take a facility layout and mark where the air should flow to ensure that contamination does not occur. Often you will need to also mark other flows on this map as well, such as the flow of raw- and in-process materials, product, personnel, waste, chemicals, and so forth, to ensure that the air flow will not carry contamination from one of these activities to another.
Restrooms are an area of particular concern when it comes to airborne contamination. All restrooms should have negative air pressure to ensure that air flows into the restroom and not out. The air that goes into the restroom is then exhausted to the outside of the building. Restroom doors should not open directly into production, packaging, or storage areas.
If you have not already done so, then obtain a facility map, and mark the desired airflow on the map. This air flow may be revised as you compare it against other flow diagrams that you will create as part of other implementation steps (such as for materials flow, waste flow, and chemical flow). This is because changes may be necessary in order to prevent air flow from carrying contamination from one activity (e.g. waste flow) to another activity (e.g. material flow) and creating cross-contamination risks.
Involve your consultant in the process by inviting him or her to review the map and make suggestions about your air flow. You may upload your first draft air flow diagram using the links below.
Air Filtration
Dirty air from outside the facility, and contaminated air from within the facility, will probably need to be circulated through an air filter to meet your air quality standards. Without proper filtration, outside air with microbiological and chemical contaminants could easily enter the facility and contaminate product. In general, intake units should be equipped with filters capable of removing airborne particulates of 50 microns in size or larger. More sensitive operations may require even finer filtration.
You may have heard reference to cleanrooms and ISO classes. A cleanroom is a room where particularly sensitive activities are performed that require high cleanliness and low levels of airborne particulates. Airborne particulates include such things as dust, microorganisms, or vaporized particles. Cleanrooms can be classified into ISO classes depending on the number of particles per cubic meter that can be found in the air. An ISO 9 cleanroom basically has normal ambient outdoor air in it with around 35 million particles per cubic meter. An ISO 1 cleanroom has only 12 particles per cubic meter. Cleanrooms are most common in pharmaceutical applications where you might find an ISO 5 cleanroom. To formally classify a cleanroom, you will need to have it tested and certified to the required ISO class.
Air filtration requirements may vary from facility to facility and room to room, depending on a risk assessment. However, as a general rule, ensure that your intake units are equipped with filters capable of removing airborne particulates of 50 microns in size or larger. Or if you have more stringent requirements, ensure that you meet those requirements.
Also, if your process requires compliance to the requirements of a particular ISO class, then disclose this to your architect and engineers, as well as your consultant, so that they can help you ensure that you meet those requirements.
You may communicate your air filtration status to your consultant using the links below.
Air Ventilation
Proper air ventilation is also important to prevent cross-contamination. Ventilation is the process of changing or replacing air to control temperature — or to remove any combination of moisture, odors, smoke, heat, dust, airborne bacteria, fumes, and carbon dioxide — or to replenish oxygen. The air exchange frequency that you will need will depend on your unique circumstances. Some environments may require as many as 30-60 exchanges per hour.
Air ventilation can help with condensation issues. Condensation can lead to mold, odor or microbiological concerns that could affect the manufacturing environment.
Air ventilation can also help to vent harmful vapors. Any chemicals, such as cleaning agents or pest control agents should have adequate ventilation to prevent vapors from contaminating any product. If you employ a solvent in your manufacturing process, then fumes from the solvent will need to be ventilated.
Proper air ventilation also serves to keep product dust from settling and attracting microorganisms or pests. Product dust, when cross-contaminating with other product dust, could cause serious health concerns for consumers who may be allergic to one of the products. Examples include areas where there is mixing equipment or seasoning that occurs. An effective air quality program will help address these concerns and reduce product dust from traveling.
Consult with your architect, engineers, and consultant regarding the appropriate air exchange rate for your activities. Considerations include temperature, humidity, condensation risks, fumes, odors, smoke, heat, product or other dust, airborne bacteria, carbon dioxide, or even oxygen replenishment. A risk assessment may need to be performed.
Another concern with air ventilation is the placement of intake vents and blowing vents in relation to your production areas. Ensure that your vents are strategically placed to avoid pulling or pushing air across sensitive areas, materials, or products.
Notify your consultant of your air ventilation considerations and determinations. You may use the links below or contact the consultant at any time via other means. Your consultant will proactively track whether implementation steps have been addressed satisfactorily as part of the consulting service, so, he or she will reach out to you later if needed.
HVAC Maintenance
Along with knowing what is required of an air flow system, proper maintenance is also crucial. All air handling units should be included in the preventative maintenance schedule. The frequency of cleaning and maintenance will be determined by the type of environment the handlers are in and may be determined by seasonal conditions. Detailed inspections or air plate monitoring may help determine the frequency that cleaning, or sanitation is required. Keep a record of filter replacements and other maintenance activities.
Air Sampling Testing
It’s important to test your air filtering systems and air handlers by collecting air samples. There are air collection devices that can be used make take consistent air samples over a period of time. The frequency with which testing should occur will differ from facility to facility. Typical tests include yeast and mold tests and Aerobic Plate Count or APC tests. Each facility should determine a risk limit for possible airborne contaminants and devise a plan to eliminate, or test and control for, deviations and their causes. In some cases, you may simply want to test to establish baseline numbers to determine what would be considered normal. Then use the tests to monitor changes. It is recommended that you perform tests immediately before and after a deep cleaning of an area.
Compressed Air
Compressed air is used in many facilities, during the packaging phase, for drying or agitating a product, or when transporting or propelling a product. Compressed air is created by pulling ambient air and then compressing it. This air may contain water vapor, particulates, oil vapor, and microorganisms. Also, the air compression process raises the temperature of the air before it is then cooled, creating water aerosols and droplets of water that in turn can lead to rust and corrosion in the air compressor, and any transfer piping, that can then be blown onto the product.
At a minimum, the compressed air should be filtered to remove particles of 5 microns or larger. Sterile air filter systems require a filter capable of removing particles of .01 microns or larger. Any attachments, hoses and O-rings should be regularly inspected to ensure there is no leakage or areas where contaminants could enter the air.