Maintain Airlocks Under Positive Pressure in GMP Classified Areas

Maintain Positive Pressure in Airlocks to Control Cleanroom Contamination

Remember: Airlocks must maintain positive pressure relative to adjacent lower-grade areas to prevent contamination ingress in GMP zones.

Why This Matters in GMP

Airlocks are transition spaces between cleanroom zones of differing classifications. Maintaining positive pressure in airlocks ensures that air flows from cleaner to less clean areas, preventing reverse flow of particulates and microbes. If pressure gradients are not maintained, contaminated air can enter controlled zones, posing a threat to sterile or low-bioburden manufacturing processes. GMP mandates that pressure differentials be validated, monitored, and maintained within specified limits (e.g., ≥15 Pa). Any deviation in pressure jeopardizes environmental control and may invalidate batch sterility or product quality assurance.

Also Read: Never Touch Sterile Surfaces Without Wearing Gloves

Regulatory and Compliance Implications

FDA 21 CFR Part 211.42 requires environmental control measures for sterile product areas. EU GMP Annex 1 mandates pressure differentials between rooms of different grades and requires monitoring systems with alarms. WHO GMP and Schedule M define requirements for HVAC systems to maintain cleanroom integrity. During audits, regulators examine HVAC qualification reports, differential pressure records, and incident logs. Deviations in airlock pressure without corrective actions may result in contamination, batch rejections, or warning letters. Maintaining airlock pressure is critical for aseptic manufacturing environments.

Implementation Best Practices

Design HVAC systems with interlocking airlocks and adjustable dampers for airflow balance.
Install calibrated differential pressure gauges with digital readouts and alarm triggers.
Monitor and log pressure differentials daily or continuously via Building Management Systems (BMS).
Train personnel to report pressure alarms and avoid opening both airlock doors simultaneously.
Investigate and document pressure deviations with root cause analysis and CAPAs.

Also Read: Do Not Record Test Results Before Completing the Analysis

Regulatory References

FDA 21 CFR Part 211.42 – Design and Construction Features
EU GMP Annex 1 – Cleanroom and Airlock Pressure Controls
WHO GMP – Airflow and Pressure Differential Guidelines
Schedule M – HVAC and Airlock Control Measures