Understanding the dynamics of air patterns is crucial for environmental management and compliance with regulations. In the realm of pharmaceuticals, adhering to Good Manufacturing Practices (GMP) regulations is fundamental, and this often necessitates scientific demonstrations. A key method to demonstrate compliance is through airflow visualization studies. These studies, often known as smoke studies, are instrumental in illustrating how air moves and behaves in controlled environments.
If a company uses unidirectional airflow (UDAF) to minimize contamination risk, it must provide evidence of its effectiveness through such studies.
Over the years, airflow visualization studies have been regarded as a pivotal element of the quality by design (QbD) for filling lines. However, with the new Annex 1 revision starting in 2022, these studies have assumed a central and critical role in a company’s contamination control strategy.
Through their wide range of applications, airflow visualization studies have implications for several topics of Annex 1(2022), including:
- Cleanroom and clean air equipment qualification
- Environmental monitoring program
- Training and qualification of personnel
- CCS (Contamination Control Strategy)
Cleanroom and Clean Air Equipment Qualification
Airflow visualization is one of the qualification requirements described in Annex 15, as mentioned in Section 4.25 of Annex 1.
4.25 Cleanroom and clean air equipment qualification is the overall process of assessing the level of compliance of a classified cleanroom or clean air equipment with its intended use. As part of the qualification requirements of Annex 15, the qualification of cleanrooms and clean air equipment should include (where relevant to the design/operation of the installation):
- Installed filter system leakage and integrity testing.
- ii. Airflow tests - volume and velocity.
- iii. Air pressure difference test.
- iv. Airflow direction test and visualisation.
- v. Microbial airborne and surface contamination.
- vi. Temperature measurement test.
- vii. Relative humidity test.
Annex 1 (2022)
Conducting studies during both operational and non-operational periods is essential. The results of these studies differ and should be applied in distinct ways:
- Studies conducted during non-operational periods aim to demonstrate that the airflow within Grade A/ISO 5 areas is unidirectional and consistently flows towards areas with lower cleanliness levels.
They are also crucial for confirming that the airflow adequately covers critical surfaces without any risky backflows (where the airflow travels on less clean surfaces and returns) and for ensuring there is no contamination transfer from lower-grade to higher-grade areas.
Consequently, the outcome of these studies is an evaluation of the cleanroom or filling line’s correct design.
- Studies conducted during operational periods are intended to demonstrate that there are no aseptic interventions by equipment or personnel that would disrupt the ISO 5/Grade A unidirectional airflow directed towards critical areas where critical surfaces, critical materials, and/or products are exposed.
These studies hold great significance in assessing the impact of process operations.
The role of airflow visualization studies is further explained in Section 4.15 in the Annex 1 2022 revision.
4.15 Airflow patterns within cleanrooms and zones should be visualized to demonstrate that there is no ingress from lower grade to higher grade areas and that air does not travel from less clean areas (such as the floor) or over operators or equipment that may transfer contamination to the higher grade areas. Where unidirectional airflow is required, visualization studies should be performed to determine compliance, (see paragraphs 4.4 & 4.19). When filled, closed products are transferred to an adjacent cleanroom of a lower grade via a small egress point, airflow visualization studies should demonstrate that air does not ingress from the lower grade cleanrooms to the grade B area. Where air movement is shown to be a contamination risk to the clean area or critical zone, corrective actions, such as design improvement, should be implemented. Airflow pattern studies should be performed both at rest and in operation (e.g., simulating operator interventions).
Annex 1 (2022)
Prompt intervention in the design of cleanrooms or clean air equipment can be achieved by anticipating airflow patterns using Computational Fluid Dynamics (CFD) studies.
The purpose of CFD studies is to obtain highly detailed results regarding the flow in terms of both time and space, providing comprehensive information about the flow fields. These tests enable the determination of air velocity and pressure distribution in the work area, allowing for verification of flows during the Quality by Design (QbD) phase, which facilitates modifications to the design of filling lines.
While CFD studies offer valuable early-stage information in the design process, smoke studies are the most employed tests for airflow visualization by pharmaceutical companies.
These studies are conducted during the initial qualification of the cleanroom or filling line and need to be repeated if there are changes in validated or qualified conditions that could impact airflow (such as process modifications, operations/interventions, equipment design, or relevant regulatory changes).
A risk-based approach can be used to determine the periodic frequency of retesting.
Figure 1. Smoke study recording. Image Credit: Particle Measuring Systems
Smoke studies have specific requirements that must be met. The installation of smoke feeders should allow for proper visualization of air flows, necessitating the positioning of smoke feeders perpendicular to the Unidirectional Airflow (UDAF).
The use of flexible hoses with extensions enables broader coverage by initiating smoke release directly from the point where the air flows out of the filter.
The smoke generation should be sufficient to make any air turbulence clearly visible and indicate the direction of the air. However, the intensity of smoke generation should not excessively compromise visibility in the area.
All activities conducted during the study must be thoroughly documented, and video recordings of the performed activities should be available, in addition to the protocol and the study execution report as outlined in Section 4.15.
4.15 Video recordings of the airflow patterns should be retained.
Annex 1 (2022)
To ensure comprehensive recordings, HD cameras should be utilized, and in certain cases, multiple cameras from different perspectives may be required. The videos should offer clear visibility of the operators’ activities and their impact on airflow. Proper positioning of the camera(s) is crucial to capture the conducted activities accurately.
During smoke studies, achieving appropriate contrast and additional lighting sources often requires the use of black backgrounds. In cases where there are areas separated by curtains or barrier systems (such as Isolator or RABS doors), filming may be required from both inside and outside those areas.
It is important to note that having a skilled cameraman alone is insufficient; the video director(s) must possess extensive knowledge of the process and expertise in sterility assurance.
The presence of an experienced team during the recording process can lead to significant time and cost savings, avoiding the need for future repetitions of the videos.
A frequent mistake is filming only a portion of the activities related to the process. The recording should continue for as long as necessary to capture all simulated activities, including set-up, monitoring, material transfer, and personnel flows.
Airflow visualization is part of the justification needed in a CCS, as outlined in Section 9.22 below.
9.22 Where aseptic operations are performed, microbial monitoring should be frequent using a combination of methods such as settle plates, volumetric air sampling, glove, gown and surface sampling (e.g. swabs and contact plates). The method of sampling used should be justified within the CCS and should be demonstrated not to have a detrimental impact on grade A and B airflow patterns.
Annex 1 (2022)
The findings of an airflow visualization study can play a critical role in validating Vaporized Hydrogen Peroxide (VHP) cycles in smaller environments like isolators.
When determining the positioning of chemical indicators (CIs) and biological indicators (BIs) for bio-decontamination cycle validation, airflow is one of the factors to be considered. Visualizing airflow helps identify areas that may be more critical.
Two factors that contribute to the criticality of an area are the presence of turbulent motions and the accessibility of the area for the bio-decontaminating agent.
Furthermore, there is a significant correlation between air visualization studies and aseptic process simulation (APS) in terms of validation. The outcome of air visualization studies is one of the factors that must be considered during the risk assessment of different simulated interventions.
As mentioned earlier, the activities associated with the study should be documented in a protocol outlining the responsibilities for execution and review.
The protocol should include a comprehensive list of materials, equipment, and acceptance criteria discussed in the document. It should provide a master list of operations to be simulated and a detailed description of the process and the area impacted by the study.
The study results should be documented in a report that includes a discussion of the findings. If the acceptance criteria are not met, it is crucial to investigate and identify the root cause, followed by defining a Corrective Action Preventive Action (CAPA) plan.
CAPAs with low impact often involve changes in operating procedures or the introduction of tools during aseptic manipulations. In more severe cases, modifying the design of the cleanroom or filling line may be necessary.
Environmental Monitoring Program
The revised Annex 1 now mandates verification through air visualization studies to ensure that monitoring systems and associated activities do not negatively impact airflows.
This entails conducting studies with the installed systems and simulating and documenting all monitoring activities. The findings of the air visualization studies should be taken into account when determining the positions for monitoring.
4.15 … The outcome of the air visualization studies should be documented and considered when establishing the facility’s environmental monitoring program.
Annex 1 (2022)
Before determining monitoring locations, it is essential to evaluate the results of air visualization studies and assess the impact of systems on airflows. Should the studies be repeated both before and after the installation of monitoring systems? The straightforward answer is yes, although it may not be the most straightforward option to implement.
To address this challenge, one potential solution, as explained in the previous section, is the utilization of Computational Fluid Dynamics (CFD). CFD can serve as a valuable tool for predicting airflows and performing initial analyses prior to the physical installation of systems.
Airflow visualization studies are very important, though, and there are several outcomes of the air visualization studies that need to be considered when establishing a monitoring plan.
The presence of turbulent air motions can facilitate the transfer of contaminants within an area, potentially leading to the transportation of contaminants from surfaces adjacent to the process to critical areas.
Conducting a thorough analysis of air visualization studies, particularly during operation, can bring attention to other risky situations.
For instance, it can reveal scenarios where air from dirtier areas enters cleaner areas or where air passes over the operator’s garments and subsequently reaches sterile surfaces. If such outcomes are observed in airflow studies, appropriate actions should be taken.
In cases where the design of the cleanroom or clean air equipment cannot be modified or where operational procedures cannot resolve the issue, monitoring becomes an important tool for mitigating risks.
Therefore, when conducting risk assessments to define a monitoring plan, air visualization studies play a crucial role. For example, in processes involving active operator involvement near or within critical areas, air visualization studies can assist in determining which area of the sterile gown should be monitored following each intervention.
Training and Qualification of Personnel
As mentioned in the previous section, air visualization studies offer a significant advantage by visually demonstrating the impact of production activities on airflow. The ability to visualize the consequences of one’s actions is what makes any form of training effective.
In sterility assurance, it can be challenging to enhance the sensitivity of operators involved in processes, particularly if their knowledge level on the subject is limited.
To address the potential limited knowledge level of subjects, the revised Annex 1 emphasizes the importance of including the review of air visualization studies as part of personnel training and qualification, as described in Section 7.18 below.
7.18 Activities in clean areas that are not critical to the production processes should be kept to a minimum, especially when aseptic operations are in progress. Movement of personnel should be slow, controlled and methodical to avoid excessive shedding of particles and organisms due to over-vigorous activity. Operators performing aseptic operations should adhere to aseptic technique at all times to prevent changes in air currents that may introduce air of lower quality into the critical zone. Movement adjacent to the critical zone should be restricted and the obstruction of the path of the unidirectional (first air) airflow should be avoided. A review of airflow visualization studies should be considered as part of the training program
Annex 1 (2022)
A valuable tool that can be incorporated into this process is the utilization of virtual reality (VR) for simulating high-risk operations. VR enables operators to visualize the impact of various production activities on airflow without any potential negative consequences on the actual process.
This approach has the potential to save significant time and resources. However, the currently most employed method for training is the review of smoke studies conducted during both operation and idle conditions.
By reviewing smoke studies in both at-rest and operational states, operators can observe and comprehend the differences in airflow resulting from different activities. If the smoke study is conducted accurately, the recorded videos can serve as effective training tools for executing aseptic techniques correctly. Practical simulations should also complement the video training.
Additionally, during the review process, it can be beneficial to simulate common errors during the visualization studies purely for training purposes.
For instance, examples may include interrupting the “first air” (Grade A air exiting HEPA filters in a unidirectional manner) directed towards critical areas where sterile materials and products are exposed, neglecting the use of necessary tools, or prolonged opening of filling machine doors.
Based on the aforementioned reasons, the review of smoke studies should be an integral step in qualifying operators to enter and perform activities within the cleanroom.
Contamination Control Strategy (CCS)
As mentioned throughout this article, conducting air visualization studies is a crucial step in developing a contamination control strategy (CCS). This activity not only contributes to the understanding of the process but also aligns with the new Annex 1 revision, which emphasizes the significance of personnel training and qualification in our CCS.
During the development of the CCS, the examination of recorded air visualization studies (alongside other pertinent materials) is necessary to identify any deficiencies in the process.
Proper execution of air visualization studies can serve as an important tool for mitigating certain risks, particularly those associated with activities involving operator handling (such as setting up sterilizing filters or sterile machine components) and exposure to critical areas.
It is considered good practice to establish internal guidelines for the accurate execution of these studies and to repeat them if deemed necessary upon completion of the CCS drafting process.
Conclusion
Air visualization studies hold significant importance in the revised Annex 1 and have drawn considerable attention from regulatory agencies in recent years.
To comply with regulatory requirements within the specified timeframe of Annex 1, it is crucial to accurately outline instructions for conducting these studies in a standard operating procedure. It is also necessary to review existing recordings, repeat the studies if needed, and update the site’s contamination control strategy accordingly.
Incorrect execution of air visualization studies can lead to an inaccurate assessment of process-related risks, challenging the qualification of cleanrooms, clean air equipment, and the monitoring plan.
The design of these studies necessitates collaboration among various departments within the company, such as engineering, manufacturing, quality assurance (QA), and sterility assurance.
Given their impact on the site’s contamination control strategy, the presence of a sterility assurance expert is required from the early stages of the studies to their execution in the field and analysis of results.
The videos obtained from these smoke studies are considered raw data and should be treated as such, with a particular emphasis on maintaining data integrity.
In summary, meeting the expectations of inspectors requires a well-defined workflow for managing these studies, involving active participation from all relevant departments.
Transparency in content, adherence to the principles outlined in relevant documents, and proper utilization of raw data for training and contamination control risk assessments are crucial components to fulfill regulatory expectations.
Acknowledgments
The original material was authored by Luca Calisi, Advisory Specialist at Particle Measuring Systems.
References
- Annex 1, Manufacture of Sterile Medicinal Products -The Rules Governing Medicinal Products in the European Union Volume 4 EU Guidelines for Good Manufacturing Practice for Medicinal Products for Human and Veterinary Use - 22.8.2022 C(2022) 5938 final
- US CFR Title 21, Part 211.
- PIC/S PE 009-16, Annex 1 (2022)
- FDA Guidance for Industry, Sterile Drug Products Produced by Aseptic Processing (2004)
This information has been sourced, reviewed and adapted from materials provided by Particle Measuring Systems.
For more information on this source, please visit Particle Measuring Systems.