Share thisSeveral articles appeared recently in Animal Lab News about the importance of bio-containment in the planning and design of research animal laboratories.1,2,3 As these papers state, the planning, design, construction, and commissioning of these facilities is difficult and complex for many reasons. These reasons include complying with regulations and guidelines, accomplishing the work mission, identifying potentially hazardous agents, performing a risk assessment on the proposed agents and operations, providing an environment free from worker, environmental exposure, and doing all this within budget restraints.
Today’s Biomedical Containment Facilities
Today’s workers are more concerned with safety than ever before. The decrease in the OSHA Permissible Exposure Limit of formaldehyde over the past 20 years is just one of many examples of increased safety regulations. The laboratory use of potent, hazardous biological agents, chemicals, solvents, novel drugs, and substances of unknown and increasing toxicity are continually expanding. Many laboratory tasks previously done in the open are now performed in hoods and other specialized vented areas.
Containment: the Key to Performance
It was recently reported at an annual EPA Laboratory Design meeting that when thousands of laboratory hoods with face velocities between 80 and 100 fpm were evaluated for containment 17% failed to meet the tracer gas (SF6) control level of 0.1 ppm specified by ASHRAE.4,5 It was also reported that when 366 laboratory hoods were tested, 51% met the face velocity requirement of 80 to 100 fpm but only 29% met the ASHRAE containment criteria.6
Many laboratory and safety personnel do not realize that face velocity and the number of room air changes per hour have a poor correlation with hood containment. Both the American Industrial Hygiene Association and the American National Standards Institute have stated that face velocity alone is an inadequate measure of hood performance.7 The only proper measure of hood performance is containment. How well does the hood capture and contain the hazardous materials being used in the hood or vented enclosure?
CFD and MRI: the Tools of Visualization
It’s very difficult to visualize the flow of air in laboratory hoods and vented enclosures. A new technique called Computation Fluid Dynamics (CFD) has changed laboratory hood technology. The application of CFD to laboratory ventilation and engineering controls is comparable to the application of Magnetic Resonance Imaging (MRI) in biomedical science. Just as MRI enables us to see inside the animals’ body it is now possible to see the behavior of air inside hoods and see how the hood will perform before it is built.