Cleaning a laminar air flow hood is a housekeeping chore that is required to maintain sterility levels in a laboratory. These hoods are also known as biological safety cabinets, and they work by maintaining a curtain of fast-moving air around a central work chamber to keep contaminants, dust and debris out of the workspace. They are used by scientists to culture living cells and microorganisms or to carry out experiments (such as on anesthetized animals), which require the highest level of hygiene and sterility to prevent surgical infections from occurring. Hood cleaning should be done regularly and by all users.
Prepare all necessary cleaning equipment. Collect 70 percent ethanol, SporKlen, MB10 or whatever disinfectant is recommended by your hood manufacturer. Avoid using soap and water. Autoclave packets of sterile gauze, Kimwipes, C-Fold towels or other laboratory-grade wipes. Never reuse these. Request biohazard trashbags if these are not freely available as well as biohazard tags if necessary (for example, if virus, radioactivity, blood or other potentially hazardous objects are used in your laboratory).
Dress appropriately with personal protective equipment. This is a basic requirement in all laboratories and for handling any type of laboratory-based tool, equipment or material, whether or not you are a scientist. Remember that even if you do not handle biohazards, others may, and many areas of the laboratory are routinely contaminated with corrosive chemicals or infectious organisms. Put on gloves, face and eye protection, full-coverage footwear (no open-toe shoes) and laboratory gowns or coats. If your laboratory handles noxious fumes, put on a respirator.
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Turn the hood on. Open up the hood cover or sash and switch the power on so that the draft of air begins to circulate, and allow this to equilibrate for at least five minutes before starting. Observe the chamber in the meantime–look for any debris, stains, spills or contaminants that pose a hazard. Also look for objects such as laboratory tools and implements that are not part of the hood (such as tube racks, holders, pipette boxes and surgical items).
Remove all "foreign objects." This means any item that is not part of the hood, or that was placed inside the hood for experimental use. As a rule, it is best not to leave such items in the hood over an extended period, since they can accumulate dust or debris. While still in the hood, open up an autoclaved container or sterile box, and place the items inside. This maintains some sterilty of the objects during transport by preventing their exposure to the environment. Place the objects in an enclosed shelf or other external storage area. If these items are to be returned to the hood after cleaning, they must be ethanol-decontaminated, UV-sterilized or autoclaved prior to use.
Clean up all debris, stains and spills. Remove airflow grates and work surfaces and mop up spills or use a hood vacuum to remove dust and debris. Spray decontaminant or disinfectant and clean this off with the sterile wipes. Do the same for all the internal hood surfaces, including the back and front of the hood. Check that whatever disinfectant is being used is compatible with the acrylic or plastic surfaces, such as the front screen of the hood, or any gas knobs inside the chamber. Replace the air grates and work surfaces and clean these as well. Do not overscrub any of the surfaces. If stubborn stains are present, pour a generous volume of disinfectant over them and soak for 10 to 15 minutes before cleaning. Repeat this on any cracks or crevices that are difficult to clean. Once the inside is clean, disinfect the external surfaces of the hood, paying special attention to areas that come into regular contact with reagents (such as fluid hoses) or staff (such as wrist rests).
UV-decontamination. Allow the hood to air-dry. Then replace the sash or cover and switch on the UV light. If the hood screen allows UV light to penetrate, do not do this until the area is sealed off to prevent staff from entering and endangering themselves. Signs may be posted to warn others. If the screen is nonpenetrative, then leave the UV light on for at least 15 minutes. Check with the manufacturer whether leaving the UV light switched on overnight is possible.