When running a production process or executing a service one should monitor how well the cleanroom or controlled environment functions when it is used.
Therefore, one can use particle counters to monitor the air cleanliness with respect to airborne particles up to 10 µm and the surface cleanliness to measure the result of cleaning and particle deposition.
However, particle counters do not count macro particles very well and measuring surface cleanliness is not easy. Therefore, particle deposition monitoring is useful as to the only monitoring method or an additional method.
Results are referred to ISO 14644 standards. These are described under particles.