Microbial monitoring in cleanroom settings pertains to identifying viable microorgan- isms in a given controlled environment. Using a volumetric air sampler, which uses
impaction to capture microorganisms, a sample can
be collected. Simply put, it is a machine that pulls air
over a given media petri dish. The petri dishes are
formulated to encourage growth of either mold or
Depending on your facility’s industry regulations, your sampling plan may require different
sampling frequencies. When talking about the
pharmaceutical industry, the current revision in
USP <797> requires sampling be done monthly.
Once a sample has been collected, it is incubated
for a specified amount time and then identified
to the genus level by a qualified microbiologist.
USP <797> has a recommended action level for
microbial contamination; each type of ISO classification has a limit to how many CFU (Colony
Forming Units) can be counted per sample.
When looking at surface sampling, there are
two options for collection: contact plates, which
are formulated petri dishes that extend over
the edge of the dish; and swabs, which act as a
media transfer device.
Table 1. Recommended Action Levels for
Viable Air Samples
(CFU per cubic meter “1000 liters”
of air per plate)
Classification CFU Count
ISO Class 5 >1
ISO Class 7 > 10
ISO Class 8 or worse >100
Table 2. Surface Samples
Classification Fingertip Sample Surface Sample
ISO Class 5 > 3 > 3
ISO Class 7 n/a > 5
ISO Class 8 or worse n/a >100
An effective environmental monitoring program provides meaningful information on the
quality of the compounding environment and
any environmental trends in surrounding areas.
In addition, an effective environmental monitoring program will identify potential routes of
contamination, allowing for implementation of
corrections. Having a professional certification
consultant help produce a proper sampling plan
from the start of your environmental monitoring program can make the difference when
a state-auditing agency inspects your facility.
When looking for a cleanroom specialist, it is
always best to look for CETA CNBT (CETA
National Board of Testing).
Shane Morris is with Champion Aire. The headquarters are located in Belleville, Mich. smorris@
Develop the right sampling plan for your facility.
in Cleanroom Settings