Particle deposition monitoring

A cleanroom is used to prevent deposition of unwanted particulate contamination on a product or patient. However, in a cleanroom we do not know how high the likelihood is of particles or micro-organisms to deposit on critical surfaces is.

A cleanroom installation removes airborne particles by air flow. Not all particles > 5 µm are removed by air flow because of deposition on all surfaces. The number of particles that are not removed because of deposition increases with particle size (50 % for particles > 80 % for particles > 25 µm and >90 % for particles > 40 µm).

Imagine having accurate real time data on particle deposition within your cleanroom. Then you know if your cleanroom is (still) good enough or if additional (operational) improvements are required for your process and product.

A contamination risk assessment determines the critical number and sizes particles that can cause product rejection and quality loss. Cleanrooms are used to establish control of the contamination risk. In a cleanroom clean products can be kept clean.

When a cleanroom is in operation, we need to be sure we are in control. This is proven by monitoring air cleanliness and particle deposition so that the chosen cleanroom concept continues to meet the requirements.

We need to demonstrate control. Therefore, the air cleanliness is monitored. However, particle counters are only reliable for particles up to 5 µm. For particles larger than 5 µm the contamination control solution should be monitored by measuring the particle deposition rate.

Particle Deposition Rate show a direct relation with contamination risks.

The Particle Deposition Rate is expressed in the number of particles per area per period for example, number of particles > 5 µm per dm2 or m2 per hour.

Major contamination risks

Air cleanliness is determined by the cleanroom installation and the way the cleanroom is used. The operational quality of a cleanroom is determined by:

  • The number of people and clothing discipline.
  • Entry procedures for personnel and materials.
  • Working methods.
  • The cleaning program of the cleanroom.
  • The cleaning workplace, tools and equipment by the operator.
  • Behavior of everybody in the cleanroom.


The APMON monitors the deposition of particles at the location of the sensor(s) real-time 24/7. The APMON is derived from the APMON PRO. The APMON PRO is already used in many companies all over the world.
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