Smoke Test MyFog

Smoke test with MyFog: not only airflow visualization

AM Instruments smoke test not only allows to visualize airflows, but, in response to the increasingly demanding requirements of inspection agencies, it also identifies potential areas of process risk and it supports the identification of corrective actions: a trusty ally for quality.


For years AM Instruments validation team has been offering a smoke test service. Our expertise, together with the experience, generated an operating mode that can be summarized in a fundamental concept: as AM Instruments Validation Manager Roberto Stroppa says: ”Smoke tests cannot and must not be a simple airflow control, but a careful analysis of all elements that contribute to the contamination control. It is no coincidence that in the last years inspection agencies have used smoke tests as verification test that considers both airflows, but also, and especially, operative dynamics”. This way the “in operation” state becomes prevalent in comparison to the one “at rest”.


Smoke tests trigger a sort of domino effect, in which an airflow control becomes the motor behind subsequent and consequent controls and verifications. Operators’ behaviour inside the cleanroom, their exact adhesion to SOPs, their education and process quality become verifiable thanks to the visualization of smoke flows. Inspection agencies, indeed, have often questioned tests that did not contemplate those phases which are not directly related to airflows, such as transfer of materials between different zones.


Our successful instrument for smoke tests works with:

  • FWI (Water For Injection)
  • Only one operator
  • Remote control
  • High quality dense smoke
  • Visualization of speed and directions of airflows in classified environments
  • Balancing of pressions between rooms through visual indication
  • Support to the identification of areas of air stagnation
Smoke Tests MyFog


Studies on airflow visualizations aim at demonstrating, on the one hand, the visual evidence of unidirectional airflows in aseptic structures and, on the other hand, the ability of the system as a whole to protect the product and the critical areas through a constant passage of primary air coming from absolute filters.

Airflow visualization studies must be carried out in “at rest” and “in operation” state and they are particularly suited to throw light on potential sources of physical or biological contamination risk in a production process or in its surrounding environment. The visualization study, more commonly referred to as “smoke test”, takes into account the most common sources of risk that can be provoked by:

  • Inappropriate design of critical production areas
  • Problematic airflow management of the ventilation system, whether it is centralized or purpose-built through LAFs (Laminar Air Flow) located in the most critical zones of process
  • Intervention of the personnel that interrupts the unidirectionality of airflows during aseptic operations

The execution of a good airflow visualization study allows the team to identify areas of potential risk of process and supports in the identification of corrective actions, allowing, therefore, the evaluation of efficacy after the implementation.


From a regulatory perspective, regulatory agencies have intervened on more occasions through observations and warning letters, reporting the lack of adequate tests that could document an appropriate airflow both in “at rest” and “in operation” state.

Inside observations and warning letters they particularly cited the CFR 21 part 112 (b):

Appropriate written procedures, designed to prevent microbiological contamination of drug products purporting to be sterile, shall be established and followed. Such procedures shall include validation of all aseptic and sterilization processes…

…where the operator interrupts the unidirectionality of the airflow creating a turbulent air motion, or, during test time, in case the angle of the room does not allow a correct airflow visualization, or the reagent source is not effectively positioned.

Other observations report that:

  • Smoke tests in ISO 5 hoods have not been carried out during “in operation” state
  • No evaluation study of the airflow model has been carried out during aseptic operations
  • No evaluation of the airflow configuration has been carried out in order to determine if personnel activities or manual transfers of materials between ISO 8 and ISO 7 negatively influence the air movement and the cascade of air
  • Smoke studies have not been adequately documented
  • Video of airflow model does not include data to appropriately evaluate the potential impact of the product on turbulence by observing vortexes in the middle of ISO 5 hoods during “in operation” state


In order for a study on airflow visualization to give a concrete benefit to the process for which it is designed, it is fundamental that its execution and technical and qualification documentation is organized in a clear and objective way. All phases submitted to the test must be clear, in particular those concerning test conditions and investigated process phases. The evidences provided must be organized by giving particular attention to the integrity of raw data collected during the study and on which final conclusions are based.


As resulting from FDA observations, there are some fundamental elements that must be studied during a correct visualization test:

  1. In the preliminary stage it is fundamental to accurately study the environment layout and the instruments it contains. It is very important to have a precise picture of operations that are carried out during “in operation” state from operators during work cycles.
  2. Determine in advance the video-operator’s movements according to the specifications described above: taking into account the potential obstacles or the possibility to keep the camera at a right distance from the flow, it is essential that video shots are studied in advance and, in case, designed from different angles according to the specific needs.
  3. Type of smoke generator and type of reagent


The success of a smoke test often requires tools which are essential to deal with executive difficulties. MyFog offers a wide range of “intelligent” tools:

  • Supplementary tools for tube extensions
  • Multi-hole rigid tubing for fog curtains
  • Tripod with support
  • Trolley
  • Case with wheels for transport
  • “Follow me” tube