once it is steam disinfected and verified as inacti- vated. A drain is situated under the tanks to contain leakage, should that occur.
The specialized HVAC unit dedicated to the independent air system of the BSL-3 and -4 suites is located on the roof of the Natural Sciences Center, while the decontamination facility is positioned un- der the BSL-4 laboratory. Computers are used to analyze temperatures, airflow, and the rooftop ex- haust systems, which are actively engaged. In case of power failures, a natural gas backup system is in place to maintain air purification, negative pressure, and equipment power.
It is critical to be able to monitor the tempera- ture and air supply for each of the high-containment suites by computer on site or from remote locations by the extensively trained and certified engineer re- quired to maintain the facility. The outer hallways are kept at negative pressure assessed by magnahel- ics, and with each step further into the biocontain- ment areas the negative pressure gradient increases according to the specifications outlined in the CDC’s Biosafety in Microbiological and Biomedical Laboratories.
which relies on the standard biocontainment gear, in the BSL-4 facility. Working in a cabinet lab is ex- tremely challenging, but considered safer than a suit lab because the individual uses large glove ports and is separated from the pathogen by thick stainless steel. The cabinet lab at the Center is 32-feet long and can accommodate three or four researchers at a time. A nearby animal section houses mice, rats, and rabbits, and a screen built into the cabinet allows investigators to visualize materials analyzed by an inverted, phase-contrast microscope.
Working in the cabinet lab can sometimes lead to fatigue because scientists must do all of their work using arm-length gloves to maneuver materials within the stainless steel cabinet while working in a line with other researchers. Working in the suit lab allows scientists to use the traditional lab layout and to move around more freely. However, breathing the positive-pressure air in the suit can also cause fa- tigue.
Barrier protection masks are worn at all times in the BSL-3 and -4 labs. Only 10 people on Hilliard’s staff are trained to work in the BSL-3 lab, while only five of these can enter the BSL-4 facility.
“The goal of the BSL-3 rooms is to isolate viruses from small samples. In order to process the samples, pull out the virus, and identify unusual agents, we have to have incubators that are fed five percent car- bon dioxide and 95 percent air,” explains Hilliard. “We can’t bring tanks in and out of these rooms, so we have a separate alcove which houses the gas tanks feeding the incubators in the BSL-3 and BSL-4 labs.”
“The masks are basically a reminder for us not to put our double-gloved hands up to our faces. If we relied on them as filtration or personal protection devices, we would go to something different,” says Hilliard. “All agents are handled in a Class 2 cabinet in the BSL-3, so there is no time at which an agent is uncapped in the room surrounding the cabinet.”
It is challenging to keep the BSL-3 laboratories stocked and tidy at the same time, keeping in mind that many of the items that come into the labs are not going to leave until they are thoroughly melted down by repeated autoclaving. Disabled equipment cannot be removed from the laboratory for mainte- nance or repair. Tools for minor repairs are decon- taminated with gas sterilization before they are re- moved from the maximum-containment suites.
Careful consideration must be given to the in- stallation of all systems and how they will interact. The HVAC system at GSU had been repaired at an annual cost of $12,000 every year since Hilliard’s lab moved into the facility. A new HVAC system specifi- cally engineered after analysis of previous failures was installed at a cost of $250,000 and 2003 marked its first year of operation.
Keeping the Scientists Safe
Necessary precautions are taken to protect the researchers while they are working in the laborato- ries. Scientists usually work in a cabinet or a suit lab,
“This is an existing building that we modified. It wasn’t meant to be under constant negative pressure and that has caused substantial stress on the walls and ceiling,” says Hilliard. “Careful consideration of the systems that are linked is very important. We are