One final item to discuss is the periodic tasks for demonstrating continued compliance of a cleanroom with ISO 14644 standards. These tasks include the following:

• HEPA filter leak testing: every 6 months for ISO Class 5 and lower classifications, every 12 months for classifications >ISO 5
• Particle classification: every 6 months for ISO 5 and lower, every 12 months for >ISO 5
• Airflow volume or airflow velocity: every 12 months
• Air pressure difference: every 12 months.

Because of the routine particle counts in operational conditions, verification of the classification of a cleanroom is usually performed under “at rest” conditions. Retrospective review of in operation particle counts may be used to demonstrate compliance under “in operation” conditions. Review and trending of viable and non-viable particle counts should be part of a quality system for any aseptic processing facility.

Air pressure difference can also be satisfied by review and trending of routine monitoring results—most building monitoring systems have the capability of trending differential pressures. With “in operation” particle counts and differential pressures satisfied by routine data, periodic recertification activities are limited to HEPA filter leak testing, “at rest” particle counts, and airflow volume or airflow velocity.