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Environmental Monitoring

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Environmental Monitoring (EM) allows you to examine the conditions under which work is conducted and to investigate any contamination incidents.  In GMP environments it is conducted to demonstrate that the manufacturing environment is under control. 

Sampling locations and adequate sampling are critical components of an effective EM and should be specified in the written program or standard operating procedures. This is one area that we can work closely with our clients to develop.


There are several components involved in an EM program. It is important to understand these components, which will help in the selection of appropriate test methods to implement an effective and robust EM program.

Air (Passive and Active)

Air quality can be determined by either active (direct) sampling, in which a given volume of air is examined using a sampling machine, or by passive sampling using settle plates which give a measure of the sedimentation of contaminants over time.

In direct sampling the air is drawn into the sampler and directed onto the surface of an agar plate. The volume of air to be examined will depend on the location. Areas suspected of having high microbial loads need to have smaller volumes tested than those in which the air has been highly filtered and numbers should be very low. With our in-line filter device, we can also sample compressed air.

Settle plates allow for the detection of microbes circulating in the air and setting onto a surface. This allows for the monitoring of a given area over a period of time, unlike the direct method above which measures the air quality for a specific volume, usually collected over a short time.


Surfaces can be examined in 1 of 2 ways. Direct contact plates (Rodac plates) can be used on flat surfaces such as benches, walls, floors, etc. Microbes present will adhere to the agar and following incubation, the number present can be determined.

For more awkward surfaces that are not smooth e.g. filling nozzles, door handles or where a larger area is to be tested, swabs can be used. Once returned to the laboratory, the swab will be diluted and plated with the appropriate agar. Once incubated, the plates are counted and the results per swab or area determined.


In some clean room operations it is necessary to take samples of operators hands (finger dabs) or protective clothing to monitor gowning effectiveness and hand cleanliness.



Agar plates can be supplied by Eurofins | ams. A lead time of at least 2 days is required so that we can perform sterility and QC checks before we send them out.

Swabs need to be examined within 24 hours of sampling to give an accurate result of the surface in question. Swabs should be sent in an esky with cooler bricks to prevent microbial growth in transit to the laboratory.

Plates should be sent in an esky to minimize the effects of any adverse conditions during transport. However, the use of ice bricks with plates is not advisable since this can lead to problems with water condensing on the surface of agar plates leading to inaccurate results.

For air samples please include: the type of air sampler used, the volume of air sampled and if you are using a device other than the AES sampler any correction factors  we will require for our calculations.


The times listed below are standard for bacterial, yeast and mould counts. If you have specific requirements then these may vary.


Method CodeTest DescriptionTurnaround Time
TME-113 Surface Swab count 5 days
TME-124 Settle and Contact Plate count 5 days
TME-217 Air Sample count 5 days