ISO 21501  

Learn how to prepare for the latest changes to standards and regulations while improving operational efficiency.

ISO 21501 is a new family of standards describing the instruments and calibration requirements for determining particle size distribution using light interaction methods. It represents the culmination of work by instrumentation manufacturers and industry users and comes at a critical time for the Life Sciences industry with the increasing trend for real-time air particle monitoring in clean rooms using light scattering air particle counters.

For cleanroom users aseptically manufacturing pharmaceutical products for the European and American markets, there is a requirement to follow the guidelines in EU GMP and cGMP respectively. Both documents define the airborne particulate count limits for different cleanroom operations, but neither defines the methods required to determine these count limits, nor do they define the instrument to be used and how it should be calibrated. However, EU GMP states that ISO 14644-1 should be used for methodology to determine cleanroom air particle cleanliness classification and that ISO 14644-2 should be used for methodology for demonstrating continued compliance. The introduction in ISO 21501-4 states "Monitoring particle contamination levels is required in various fields, e.g. in the electronic industry, in the pharmaceutical industry, in the manufacturing of precision machines and in medical operations. Particle counters are useful instruments for monitoring particle contamination in air. The purpose of this part of ISO 21501 is to provide a calibration procedure and verification method for particle counters, so as to minimize the inaccuracy in the measurement result by a counter, as well as the differences in the results measured by different instruments." The scope of ISO 21501-4 states "Instruments that conform to this part of ISO 21501 are used for the classification of air cleanliness in cleanrooms and associated controlled environments in accordance with ISO 14644-1". So the importance of ISO 21501 to cleanroom users looking to follow the guidance in GMP is evident.

The ISO 21501 family of standards extends beyond air particle counters to include both scattering and extinction type liquid counters. The standard is split into four parts and all are available from ISO at New Window.