Environmental Monitoring

Good Manufacturing Procedure (GMP) mandates the air quality conditions for biopharmaceutical production in cleanrooms. The real danger is the microbes on the human body. Humans shed around 30,000 skin cells per hour3, all of which are potential carriers of microbes. Unfortunately, we do not currently have technology to detect airborne microbes real-time, so air particle counters are used as a surrogate. 1

Cleanliness Classes/Grades

The EU GMP and USA cGMP define the airborne particle counts/m3 for each cleanliness class/grade.2 There are fundamental differences between the USA cGMP and the EU GMP documents for cleanroom classes/grades. The foremost difference is that the EU GMP requires the cleanroom user to classify and subsequently monitor their cleanrooms for airborne particles ≥0.5microns in size and also ≥5microns in size, whereas the USA cGMP only requires the user to classify and subsequently monitor their cleanrooms for airborne particles ≥0.5microns only.

Clean Area Classification (0.5µm particles/ft3) ISO Designation ≥0.5µm particles/m3 Microbiological Active Air Action Levels (cfu/m3) Microbiological Settling Plates Action Levels (diam. 90mm; cfu/4 hours)
100 5 3,520 1 1
1000 6 35,200 7 3
10,000 7 352,000 10 5
100,000 8 3,520,000 100 50

Figure 1. Cleanroom classes as defined in USA cGMP


Maximum permitted number of particles per m3 equal to or greater than the tabulated size
At rest In operation
Grade 0.5µm 5.0µm 0.5µm 5.0µm
A 3,520 20 3,520 20
B 3,520 29 352,000 2,900
C 352,000 2,900 3,520,000 29,000
D 3,520,000 29,000 Not defined Not defined

Figure 2. Cleanroom grades as defined in EU GMP

As can also be seen from the tables in Figures 1 and 2, cGMP does not define airborne cleanliness levels for each cleanroom Class when the cleanroom is at rest, whereas GMP differentiates between these two states. The third major difference between the two documents is that cGMP has an additional Class between Class 100 (equivalent to GMP Grade A) and Class 10,000 (equivalent to GMP Grade B in operation) and GMP has an additional Grade D, defined as having ≤3,520,000 particles ≥0.5microns at rest.



  1. Harrison, Tony. “Automating Biopharma Quality Control to Reduce Costs and Improve Data Integrity.” Beckman Coulter Life Sciences. Page 3, PART-3506WP02.18 February, 2018.
  2. Harrison, Tony. “Changes to GMP force cleanroom re-classifications.” Beckman Coulter Life Sciences. Page 1, PART -1352WP02.16-A. February 2006.
  3. Health How Stuff Works, How many skin cells do you shed every day?, by Ed Grabianowski. http://health.howstuffworks.com/skin-care/information/anatomy/shed-skin-cells.htm, published July 6, 2010.

Products for Environmental Monitoring

Facility Monitoring System portable and remote air particle counters

Facility Monitoring Systems (FMS)

Scalable on-line particle monitoring solutions based on open architecture communications that integrate easily and enables EU GMP Annex 1, FDA and your internal quality system compliance. 
Met One 3400 air particle counter

MET ONE 3400

Portable air particle counter for cleanroom environmental monitoring

MET ONE 6000 compact remote air particle counter

MET ONE 6000

On-line air particle counter with 0.3/0.5 μm sensitivity designed for ISO 21501 compliance
MET ONE HHPC+ Series Handheld Air Particle Counters 2 3 6 Channel

MET ONE HHPC+ Series Handheld Particle Counters

The MET ONE HHPC+ series of handheld particle counters is light weight for checking ISO Class 5 validation (FED STED Class 100) or higher cleanrooms and controlled environments. It has a large screen and easy data download via a USB cable, memory stick or ethernet connection. 

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