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Clean Room vs. Dirty Room


In this article: 

As you plan the layout for your molecular lab, it's important to 
know what rooms are needed. Here is a quick explanation of the
clean room vs. the dirty room.


The Clean Room

The clean room is designated for specimen processing and for the preparation of the Polymerase Chain Reaction (PCR) master mix. This room should be kept under positive pressure, so when the door is opened you can feel the air flowing outward from the room. This helps to minimize potential outside contamination from entering the room. Medical technologists in this area have dedicated gloves, gowns, masks and other supplies that are kept strictly inside the clean room.

Lab Director Rodney C. Arcenas, Ph.D., D(ABMM), at Memorial Healthcare System in Hollywood, Fla., has two dedicated hoods in his clean room: one for specimen preparation; and one for PCR reagents. “We don’t want contamination to occur when opening the PCR reagents, so we physically separate the two processes. It’s very difficult to get rid of contamination. Be sure to have a wipe-down procedure after each use in the hood. It’s easier to prevent contamination than to clean it up afterward.”

Once PCR samples are in the reaction vessel and sealed, they can be walked out of the clean room to the appropriate instrumentation, whether it is in the dirty room or a general molecular lab area. Dr. Arcenas recommends having an “in” door and an “out” door, similar to a restaurant. This allows for good workflow and eliminates collisions with other lab techs.

“When you are handling a plate or carousel, you don’t want it to drop and break. This is a big safety and contamination issue,” he said. At the very least, depending on the lab set-up, it is important to have a unidirectional workflow.

The Dirty Room

“Due to the nature of some of our assays, the dirty room is designated for post-PCR processing,” he said. “The whole idea is to prevent any PCR contamination from being introduced into the other areas of the molecular lab.”

Here again, med techs have dedicated hoods, gloves, masks, gowns, pipettes, etc. The dirty room is under negative pressure, so when the door is opened, air flows into the room to prevent any potential PCR product from escaping and contaminating the rest of the lab.