FAQ - Pharmaceutical/Life Sciences Particle Counting

Question
Why monitor for 0.5um & 5.0um particle?

Answer

The requirement to monitoring 0.5um and 5.0um has a certain historical significance. 0.5um was the smallest particle that could reliably be monitored during the 70’s when the FDA standardized on FS209B and a move to a smaller particle would yield very little about the clean room that could not be gained from the 0.5um size. The choice of class 100 as the sterile processing area also yielded suitable microbial limits, so it was fixed at Class 100. EU followed suit using the same limits but in metric.

The 5.0um particles were used in Europe following studies which showed that free-floating viable organisms were typically 10-20um in size. Therefore monitoring for 5.0um gave two benefits:

1) This is half the value of the smaller size so it guarantees to capture particles in that range

2) It allows for correlation with the largest size used in all international standards for clean room limits.

Given that clean rooms should be "essentially" free from all large particles, meant that they would show real-time control over the viable risk to that room. Viable contamination has a much greater impact on product than non-viable contaminants in the same numbers.

The rationale for using both arises from the desire to control the clean room while demonstrating an environment suitable for sterile manufacture. 0.5um limits should reflect control over the cleanliness of the clean room - as they exist in numbers large enough to show control and control limits. 5.0um events should prove control over its suitability to be maintained in a sterile state; however the numbers of 5.0um alone are insufficient to show control of an environment.

For more information on this, including applicable graphs and images, read our paper Particle Monitoring Requirements in Pharmaceutical Cleanrooms.