Do EU GMP or cGMP guidelines require the use of a specific particle counter for air particle cleanliness classification and monitoring?

Cleanroom operators must follow EU GMP and cGMP guidelines when manufacturing injectable or infusion (bio)pharmaceuticals for European and American markets. Both documents define airborne particulate count limits for various cleanroom operations but not the method by which a cleanroom must comply with required limits.

EU GMP and cGMP point to ISO 14644-1 for the methodology to determine cleanroom air particle cleanliness classification. ISO 14644-1 states that ISO 14644-2 should be used for routine environmental monitoring. Both ISO 14644-1 and -2 mandate that particle counters must be calibrated to ISO 21501-4.