Living microorganisms can be found everywhere, including suspended in the air. Due to this fact, it is essential to monitor the air for microbial and fungal contaminants. Excessive amounts of suspended bacterial and/or fungal organisms could ultimately settle on exposed food contact surfaces.
It is recommended to monitor the level of microbial contamination in the atmosphere post-construction, after movement of equipment that has been stationary for a long period of time and /or when activities have created visible aerosols of dust particles. This method is a quantitative analysis of airborne microorganisms. A limitation utilizing this technique does not measure a specific volume of air sampled and should not be used for compressed air testing.
Passive Air Sampling Procedure
- Wash and sanitize hands before proceeding with any sampling.
- Allow refrigerated agar plates to come to room temperature before using.
- Examine plates for contamination or liquification from condensation.
- Note: Do not use liquified plates or plates with growth on them. If you notice this, please contact the lab for new supplies. Using permanent marker, label the plates or apply a pre-printed label.
- Clean visible debris and area with sanitizer before placing petri dishes.
- Transport plates to desired testing area (preferably a flat surface) ensuring the petri dish lids stay secured.
- Aseptically open plates with media side down and place covers on the sanitized surface. Do not touch the agar or inside of the petri dish.
- Allow the surrounding air to settle on plates for 15 minutes or according to your food safety protocol.
- Close plates aseptically without touching the agar, and seal it with tape or parafilm. This avoids the lid separating from the plate and potentially contaminating the sample.
- Re-sanitize surfaces where petri dishes were placed.
- Refrigerate after sampling until ready to ship/deliver to the lab.
- Note: Do not freeze agar plates! Freezing can kill microbes and could result in false low counts.
Sample Submission / Shipping Samples to the Lab
- Ensure all plates have been labeled with location description or any identifier unique to your operation.
- Fill out a sample submission or online e-Submission form with the corresponding sample description.
- Select the test to be performed i.e., Aerobic plate count (APC), Yeast and/or Mold (YM), Coliform (Coli).
- Wrap plates in a bubble wrap or a clean protective wrapping to avoid direct contact with ice packs. Secure the air plates in a manner the ice packs will not break the petri dishes during transit.
- Place in over-night ice packs in an insulated box and place the wrapped plates in the box. Note: This ensures the sample stays cool enough to protect viable cells that may be present.
- Deliver the plates to laboratory with accompanying submission form in a Ziploc/plastic bag and placed on top of wrapped plates or ship.
- Note: All plates should be shipped overnight or delivered same day to the lab for testing. For Saturday delivery, please select Saturday delivery and contact the laboratory for delivery confirmation
The laboratory results will be available within 48 – 72 hours from receipt. It is expected that 1 CFU/ plate represents 1 minute of exposure. Therefore, 1 CFU/plate x 15 minutes = 15 CFU/plate. A result greater than 15 CFU/plate may be considered out of specification. Ensure that you are following your own food safety protocols for results out of specification limitations.
Still have questions?
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