This informal CPD article ‘When Airflow Tells the Wrong Story: HVAC Deficiencies That Lead to Major Consequences’, was provided by Pharmalliance Consulting, who offer specialist support to pharmaceutical companies to maintain and increase quality compliance levels.
It doesn’t take a major system failure for your HVAC setup to land you in trouble. Subtle issues are more than technical oversights. They’re signs that your cleanroom isn’t under control. In the post-Annex 1 landscape (2), these problems are showing up with increasing frequency in inspection findings. Regulators are watching airflow, and if yours isn’t telling the right story, you’ll have explaining to do.
The Inspections Speak for Themselves
In the past year alone, both EU and FDA (1), (2), (3) inspectors have flagged HVAC-related issues as top contributors to contamination risk. Examples include:
- A site that failed to provide evidence of procedures to monitor and respond to deviations in pressure differentials between classified areas.
- A manufacturer installed new aseptic filling equipment but failed to perform updated airflow visualisation (smoke) studies to confirm that the new configuration did not disrupt unidirectional airflow.
These may sound like operational slip-ups, but they’re ultimately system design and control failures.
Why Air Still Matters Most
In aseptic processing, air is a critical control. It’s supposed to act as a protective barrier, flushing out particulates and microorganisms, maintaining sterility. But when airflow is assumed rather than proven, the whole system becomes unreliable.
Annex 1 now explicitly requires airflow visualisation (“smoke”) studies to confirm laminar flow in Grade A areas and to ensure that unidirectional flow is not disrupted by equipment or operator movement. Inspectors want more than a smoke test from five years ago, they expect to see:
- Repeat studies after layout or equipment changes.
- Studies conducted under dynamic conditions.
- Documentation that links airflow findings to CCS decisions.
If airflow can’t be visualised and justified, inspectors won’t trust it’s doing its job.
Design Issues Still Haunt Older Facilities
A recurring theme in inspection reports is outdated HVAC design. Some legacy facilities struggle to maintain pressure differentials due to undersized AHUs, poorly zoned ductwork, or deteriorating seals.
Others use manual logs to track room pressures, without any alarms or real-time feedback. That’s not a minor procedural gap; it’s a serious lapse in environmental control.
Airflow and Operator Behavior
Even in well-designed rooms, poor operator practices can interfere with airflow integrity. Inspectors have flagged situations where operators block HEPA-filtered vents during interventions or position equipment in a way that disrupts laminar flow. Facilities that do well in inspections often train operators using video footage from smoke studies, showing how simple positioning errors can disturb airflow patterns. This not only supports compliance but makes the connection between design and daily behavior more tangible.
Monitoring Systems that Keep Pace
Real-time monitoring of HVAC parameters is no longer considered optional in many classified environments. Facilities that rely on manual checks or once-a-shift pressure readings are increasingly being told to upgrade. Modern inspections expect automated systems that can detect and alert for deviations in airflow velocity, differential pressures, and filter performance. When these systems are linked to a central EMS and integrated into deviation handling, it gives inspectors confidence that problems will be caught before they affect product quality.
Linking HVAC to the CCS
One of the most consistent recommendations is that HVAC performance should not be managed in isolation. It needs to be part of the facility’s contamination control strategy. This includes documenting how airflow design supports segregation, justifying differential pressure setpoints, and using EM trends to guide maintenance schedules. Where facilities fall short, it is often because airflow is treated as an engineering issue rather than a quality control measure.
Conclusion
Airflow doesn’t get the attention that equipment or gowning does, but it should. When airflow fails, contamination becomes invisible and unavoidable. And regulators know it.
As Annex 1 tightens the spotlight on dynamic airflow control, expect this to remain a top priority in inspections. Sites that can’t show how their HVAC protects their product won’t be given the benefit of the doubt.
If you want to keep your cleanroom clean, start with what you can’t see, and make sure airflow is doing its job.
We hope this article was helpful. For more information from Pharmalliance Consulting, please visit their CPD Member Directory page. Alternatively, you can go to CPD Industry Hubs for more articles, courses and events relevant to your Continuing Professional Development requirements.
References
(1) U.S. Food and Drug Administration, 2023. Warning Letters Database, United States of America.
(2) The European Commission, 2022. EU Annex 1, Brussels, Belgium.
(3) European Medicines Agency, 2013. EudraGMP Database, Amsterdam, The Netherlands.
