Critical airflow (Smoke Studies) is used to maintain aseptic conditions when manufacturing sterile products under aseptic conditions. Smoke studies, the visualization of critical airflow, is used to demonstrate unidirectional airflow and sweeping action over and away from the product. These studies are typically performed under both static and dynamic conditions.
- Airflow visualization studies (i.e., smoke studies) are conducted to confirm unidirectional airflow patterns within an aseptic processing facility. Static studies are intended to document that the airflows within the Class A/ISO 5 zones are unidirectional and cascade out to the zones with lower cleanliness requirements.
- Dynamic studies should document that airflow within the Grade A/ISO Class 5 filling lines is unidirectional and sweeping down and away from sterile equipment surfaces, container/closure systems, and products.
- Dynamic studies work to confirm that facility and equipment design, equipment operation, and personnel aseptic manipulations (i.e., interventions) do not disrupt the “first air” (i.e., air exiting the high-efficiency particulate air filters within the Class A zone essentially particle free, in a unidirectional manner) to critical areas where sterile surfaces, materials, and products are exposed.
- Inadequate airflow (e.g., turbulence due to line design issues and first air disruption during interventions) in the critical Grade A zones, where sterile products and components are exposed, could lead to the introduction of contaminants into drug products as they are being filled and stoppered, posing a risk to product sterility.
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- A product contamination risk can result if first air is disrupted by passing over non-sterile surfaces of equipment, tools, components, or operators on its way to exposed sterile product, components, and equipment. Any viable or non-viable matter on these non-sterile surfaces can be dislodged and introduced as contaminants into the sterile drug product.
- A successful smoke study report will include a thorough analysis of the study, justifying that satisfactory airflow under static and dynamic conditions was achieved. If the smoke study finds unacceptable air flow (e.g., first air disruption by equipment operation and/or personnel interventions) or turbulence, an investigation should identify the root causes and recommend actions to be taken (e.g., filling line or equipment modification, change in personnel behavior/aseptic technique, adjustment of air velocities).
- Turbulent airflow may be acceptable in closed systems, such as an isolator, provided that studies demonstrate that acceptable particulate levels can be maintained. Smoke study video recordings are considered data that should be maintained as any other data generated on site.
- The smoke study also known as dynamic air visualization study is the key qualification, maintenance and monitoring of facility to ensure the final product is free from contamination in a processing company. The smoke study in cleanroom area is conducted to visually confirm unidirectional airflow exiting High Efficiency Particulate Air (HEPA) or Ultra Low Particulate Air (ULPA) filters in a manufacturing clean room.
- The main objective of the smoke study is to observe the pattern that is introduced to observe the airflow pattern and therefore physical properties of the smoke play a visual role in the entire qualification. The smoke study should be conducted by trained personnel with proper safety equipment.
- When performing the smoke study in a clean room area, the styles of smoke used are limited, therefore, one has to be careful when selecting a fogger because many methods are not suitable for a clean room installation.
- Some of these methods such as glycerin-based smoke are known to leave an oily residue on everything in the test area equipment personnel and the floor.
- The smoke study in the cleanroom area is important as it tells one about the airflow characteristics of the ISO (International Organization for Standardization) class 5 environment. The smoke study demonstrates the movement of the particle in a clean room. Assuming there is a visible particle in the room, with all windows closed, an open door and the air conditioning system turned on, one can clearly observe the direction in which the particle is moving within the room.
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- The particle will be driven from the HEPA (high-efficiency particulate air), over the product in cleanroom equipment, the personnel involved, the clean room floor and finally the place where the particle exit the room. In case there is a particle or an airborne contaminant in the air within the clean room the smoke test will demonstrate where the contaminant will likely move. Smoke studies are recommended during initial room qualification, new installation of equipment in the room, change in the equipment configuration, or any other changes in the existing systems.
- Since the main aim of performing the study in GMP cleanroom area is to observe the smoke that is produced to observe the airflow pattern within the room, therefore, the physical properties of the smoke play a very important role in the entire qualification. The smoke should have a similar density to that of the air. Inadequate airflow might expose the drugs to the risk of product sterility.
Advantages of Smoke Study in Cleanroom Area
- The benefits of this method are more intense longer last smoke and a more portable machine. Another benefit is a cleaner work environment and the vapor is similar to a light cooling mist.
Disadvantages of Smoke Study in Cleanroom Area
- The vapor dissipates quicker, making it difficult to capture larger areas.
The smoke study in GMP clean room area must put into consideration all possible measures to ensure best results are achieved. It is therefore very important because if the results find unacceptable airflow, an investigation should be conducted to identify the main causes and provide possible solutions to be taken to avoid any further damage from occurring currently or in future.
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