USAMRIID's second main facility is Building 1412, adjacent to Building 1425. The building was once the Special Operations Laboratory, before President Richard Nixon ended the U.S. offensive biological warfare program in 1969.

Building 1412 has been renovated extensively since its assignment to USAMRIID in 1969. The building holds laboratories, office space, animal space and the Center for Aerobiological Sciences.

The center, which reopened in the fall of 2005 after a $6 million renovation, allows scientists to test vaccines, drugs and diagnostics on animal models, as part of U.S. Food and Drug Administration licensing.

Renovations to the aerobiology laboratory increased scientists' testing capacity using aerosol, or airborne, forms of agents. A biological threat is most likely to occur in aerosol form, USAMRIID spokeswoman Caree Vander Linden said.

USAMRIID is staffed by more than 740 people and houses about 230 lab rooms in 14 containment suites, where researchers study biological agents.

Containment suites are a collection of laboratory, animal, storage and administration rooms. Suites have specific vaccination requirements dependent on types of agents used in each.

Agents are categorized into biological safety levels from BSL-1 to BSL-4. The BSL number dictates the lab facilities, procedures and equipment that must be used to safely handle agents in each level.

USAMRIID has 15,000 square feet of BSL-4 space, which hold the most dangerous biological agents. USAMRIID also has 50,000 square feet of BSL-3 space, the largest BSL-3 square footage in the Department of Defense.

Biosafety level 1 agents could be found in any microbiological environment, such as a kitchen table. These agents don't pose a disease risk to healthy adults.

Scientists use standard microbiological practices to handle BSL-1 agents, including using gloves, hand-washing and decontaminating work surfaces.

Level two agents, which include hepatitis B and HIV, pose a moderate infection risk and are present in the general human community.

Workers use personal protective equipment such as laboratory coats and gloves when working with BSL-2 agents, as well as biological safety cabinets when using infectious agents that could splash or become airborne.

Containment labs use BSCs to protect workers manipulating agents. A hood on the cabinet uses a blower to push air into the cabinet, preventing the inside particles from coming in contact with personnel.

BSL-3 labs, the level at which "containment" starts, use agents that could cause serious illness to persons exposed to them, but vaccines or drugs are available to treat the illness. BSL-3 agents USAMRIID uses include Venezuelan equine encephalitis and anthrax in aerosol form.

Personnel working with BSL-3 agents use safety equipment including BSCs in all agent manipulations, as well as BSL-1 and -2 procedures.

Workers also wear scrub suits in BSL-3 suites and must shower when entering and leaving the suite. Personnel also wear a Tyvek suit over their head and shoulders with a see-through face panel, and breathe HEPA-filtered air through a powered air purifying respirator, or PAPR.

BSL-4 agents are life-threatening, typically exotic to the United States, and there are no existing drugs or vaccines to prevent or treat infection. BSL-4 agents USAMRIID works with include Ebola and Marburg viruses.

Workers in BSL-4 suites also use BSCs and wear Chemturion-brand blue full-body suits, the texture of a pool liner. The suits, made of Chloropel with clear visors made of PVC, are under positive pressure to prevent leakage in.

Workers breathe through an air supply separate from the air in the suite, and they shower when entering and leaving the suite with both water and a decontamination chemical.

Suites employ procedural and engineering controls to keep agents inside. Pressurized suites and air handling units keep air (including airborne agents) coming into containment areas, not out of them into non-containment areas.

HEPA filtration cleans the air exiting labs, and waste leaving labs is chemically and/or thermally decontaminated. Items including laundry are autoclaved, using high temperatures and pressure to sterilize them before being handled outside containment.

Small items such as single sheets of paper are passed between passboxes to noncontainment areas, after being decontaminated with ultraviolet radiation.