Share thisLaboratories and animal facilities handling or utilizing infectious pathogens have become more complicated over the past few years. As the number of new facilities increases, there is a natural pressure to “raise the bar” of containment. If working in a biosafety cabinet (BSC) is good, isn’t working in a BSC in a room that is HEPA filtered better? If HEPA filtering the exhaust in a facility is appropriate for that facility, isn’t HEPA filtering the supply air better? If sealing a room is good, isn’t sealing it airtight better? The issue should not be “what is better” but should be “what is necessary to appropriately mitigate the risk” one is working to contain. Unfortunately, the natural tendency to increase containment requirements comes from a number of factors:
1) The tendency of users, architects, and engineers to want to create something new, rather than just doing the tried and true well.
2) The large number of new entrants into the containment field who are acquiring the experience and judgment that comes with experience. Until that judgment is fully acquired and in place the natural tendency is to err on the side of conservative decisions.
3) The tendency of those creating guidance to provide a one size fits all solution; however, this type of solution, by definition, must be a worst case solution.
4) The tendency for previous solutions to become accepted precedents.
How does one keep from entering this spiral of cost and complexity? The first step is to understand what mitigates each risk. A consistent theme in biocontainment guidelines is the concept of primary and secondary containment barriers. Primary barriers are immediately around the hazard thereby controlling contamination at the source. This is a very effective way to provide a high degree of biosafety in minimizing the exposure to workers directly involved with the hazard. Secondary containment provides a second layer of containment (usually, but not necessarily always, the facility) to protect the environment outside of the space handling the hazard. This concept is often misunderstood. The facility (secondary containment) provides no protection for the workers involved in handling the hazard, from the hazard. The protection of the workers is provided by a combination of primary containment, personnel protective equipment (PPE), and procedures to safely handle the hazard.