Applying the layers of protection analysis (LOPA) method to high containment level biological facilities.

The Layers of Protection Analysis (LOPA) method is a semi-quantitative risk assessment tool that is used to determine the ability of safeguards to protect against unplanned hazardous scenarios. One possible outcome of a LOPA is that existing and proposed safeguards are deemed sufficient to reduce the risk associated with the hazardous scenario to a level that can be deemed as acceptable. Alternatively, the LOPA may also show that the safeguards are insufficient and therefore additional Safety Instrumented Function(s) (SIF) would be required to reduce risk to an acceptable level. In the latter case, the LOPA method will inform the end user as to the reliability requirements of the safety function in question. The LOPA method has been used extensively in the process industries (e.g., oil and gas) as a useful tool to manage and understand risk and to demonstrate if the facility is 'safe' to operate, but much less so in the biosafety sector. This paper describes the LOPA method and provides some practical examples of how it may be applied in microbiological high Containment Level (CL) facilities.