The LAFH removes airborne particulate matter through the use of two types of
filters. The air first enters through a pre-filter where large particulate matter is removed.
Then the air is forced through a high-efficiency particulate air filter or HEPA filter. This
filter removes 99.97 percent of all particles larger than.3 micrometers in diameter.
Since microbial contaminants in the air are found on other particulates, the removal of
these particulates results in air-flow free of both microbial contaminates and particulate
matter. The LAFH should be located in a clean area with little traffic flow past the front
of the hood. The hood must be properly maintained and operated in order to achieve
an aseptic environment in which to prepare sterile products.
The LAFH must be periodically certified, showing that the hood meets federal
standards of operation. This is not done by the pharmacy! The pharmacy may request
the certification, but it involves complicated tests and equipment that the pharmacy
cannot provide. AR 40-2 requires certification every 12 months.
The hood should be allowed to run for 30 minutes before it is cleaned and used
to prepare products. This allows the hood to initially "purge" the room air and establish
an aseptic environment.
3-10. INITIAL CLEANING
After the LAFH has been running for 30 minutes, it is necessary to clean it. A
complete cleaning of the LAFH is done at the beginning of each shift (or at the
beginning of the day if there is only one shift).
a. To clean the work area of the LAFH, gauze pads, a nonfilming water-soluble
disinfectant/detergent solution, and 70 percent isopropyl alcohol are needed. The
disinfectant/detergent is used to remove any water-soluble contamination and disinfect
the surfaces. The 70 percent isopropyl alcohol will remove any alcohol soluble
contamination and disinfect the surfaces. Both liquids are applied with the gauze pads,
which are changed every time another area of the hood is cleaned.
b. The first cleaning is done with the nonfilming disinfectant/detergent. The
hood is cleaned from top to bottom and from back to front. The first item to be cleaned
is the light cover. The suspension bar is then cleaned starting with the top of the bar
and moving to the bottom. After the suspension bar, the sides are then cleaned. Either
side may be done first but both sides are cleaned before the work surface. Starting at
the back of the hood, clean the sides. Use vertical movements from the top to bottom.
Remember to clean from back to front. After the sides have been cleaned, the work
surface must be cleaned. Using horizontal movements, work from the back to the front.