Share thisIn this series of columns on certification, we started out discussing certification from the perspective of objective standards. These objective standards have proven difficult to achieve in biocontainment. In the first column, we discussed the possibilities in placing an additional level of objectivity on biocontainment so that "certification" to an objective standard could be met. There are certainly examples of objective standards being used in biocontainment, and there are also methods to improve the ability to objectively evaluate the risks associated with the operations, facilities, and equipment in these laboratories.
Certainly, objective standards have been developed to measure the adequacy of decontamination for reduction of risk. For example, with effluent decontamination systems, autoclaves, and space decontamination, the reduction in surrogate microorganisms by the decontamination process employed is a methodology utilized to quantify the efficacy of the decontamination methodology. Once established, the objective results of decontamination are repeatable if the methodology and parameters for the decontamination remain the same.
Protection factors that quantify the reduction in exposure to an aerosol have been used to define operator protection for different types of respiratory protection equipment as well as for biosafety cabinets. Similar methodologies have been applied to laboratory facilities to quantify the effectiveness of facility features utilizing the concept of a "laboratory protection factor." This laboratory protection factor evaluates the ability of a secondary containment feature to reduce the hazard when an aerosol is created in a laboratory space outside of primary containment. The laboratory protection factor is the aerosol concentration inside the laboratory divided by the aerosol concentration in the space outside the laboratory. In other words, how much did the feature in question (wall, double door entry, directional airflow through a door, air change rate, filter, etc.) reduce the concentration of the aerosol?
For example, Allen Bennett, Simon Parks, and their colleagues at the Health Protection Agency in Porton Down have experimentally evaluated the aerosol concentrations generated by typical laboratory accidents. They have also experimentally evaluated the protection factor at double door entries to identify the protection factor created by these features. This allows objective understanding of the "scenario" both inside the laboratory and outside the laboratory in the event of an incident that releases an aerosol outside of primary containment.
If laboratory protection factors are created for all facility features and are then measured against worst case incidents that impact the facility, an objective evaluation of the effectiveness of the facility in mitigating risk could then be made. This could be applied to alternative facility designs to evaluate which design most appropriately mitigates the planned risk. Suitable factors of safety could be applied to the calculations just as factors of safety are applied to other calculations involving risk such as in the design of concrete or steel structures.