The process of physically entering the BSL-4 containment suite and coordinating the ingress of supplies takes time, and varies depending on the standard operating procedures at individual facilities. The following section generally describes the process in US laboratories. Some facilities pass laboratory supplies or animals in cages through the hallway-airlock entry to the grey side. Anesthetized nonhuman primates in transfer boxes may also enter through this airlock, a process which must be executed quickly due to the limited time during which the animals may remain anesthetized. Other facilities are equipped with air pressure resistant (APR) doors, which allows for the direct passage of animals into an approved animal room that is under BSL-2 conditions. The animals are then allowed to acclimate and the APR door is locked from the BSL-2 side. The inner APR door from the BSL-4 side is then released and the animals transition from BSL-2 to BSL-4 for the current study. After personnel entry through a security access point into the outer change room, or the “cold” side, from the common hallway, a researcher must remove all personal items of clothing, undergarments and jewelry, except for eyeglasses, if necessary. Facility-provided laboratory clothing, basically long-sleeved surgical scrubs and socks, are donned before entry into the transitional side or “grey” side via badge reader, personal identification number (PIN) code and sometimes a biometric reader such as a fingerprint or retinal scanner. The method of personnel access is dependent on laboratory design at individual facilities. Once on the grey side, the process of donning additional PPE, checking laboratory safety features and confirming suit integrity begins, and may follow an institute checklist. Required PPE typically may include: earplugs/hearing protection (e.g., for the Dover CHEMTURION suits), one or more pairs of latex or nitrile exam gloves (sometimes taped to scrub sleeve cuffs), optional taping of socks to scrub pant cuffs, and an optional hair covering. Daily suit preparation involves visual inspection and manipulation of the suit and the outer gloves for defects. The outer suit gloves may be hefty neoprene, nitrile or latex gloves, generally 15 to 30 mil (millionths of an inch) thicknesses, and appear similar to dishwashing or canning gloves. Outer suit gloves are changed depending on the procedures employed by the institution, which may be every three entries, or at least once per week or more often if necessary, by using wide waterproof tape to attach the glove at the cuff of the suit sleeve. When gloves are changed, a suit pressure test is performed which enables the user to confirm no air leakages or holes in the suit fabric, which most frequently appear at gloves or on suit feet. Suit checks may be recorded as entries in a suit maintenance logbook. Depending on the institution, any damage found or repairs made may be reported to an institute’s safety office for consideration of appropriate action or at minimum, databasing individual suit integrity. Once suit integrity is confirmed, the suit is donned and connected to an air hose on the grey side, before BSL-4 or “hot” side entry, to confirm functionality of the air line and the coupling mechanism on the suit.
Procedures and features for entry and exit into the hot side may differ depending on the institution. When closed, the grey-side chemical decon shower door is held shut by an electromagnet and an inflated gasket surrounding the entire door (APR door), which stays inflated to block any air transfer. Access into the shower vestibule may require a PIN code, biometric reader or other possibly unmonitored opening mechanism, which deflates the air gasket bladder and disengages the magnet. The grey-side shower door is opened and the researcher, along with any supplies or animals, then enters the shower vestibule, closing the grey side door behind them. Once the grey side door magnet and air gasket are re-engaged, the BSL-4 or hot side shower door, also equipped with a magnet and air gasket, is opened. All supplies are unloaded into the hot side. Some institutions require the use of protective over-boots or foot coverings, which are stored on the hot side and donned on entry, and other places may even require the use of a third pair of gloves over the outer suit gloves. Once the shower vestibule is empty, it must be decontaminated after the hot side door is closed and before another researcher enters from the grey side. To do this, the decontamination shower is initiated, the hot side door is closed through full engagement of magnets and gaskets, and the empty shower completes its run cycle. The shower is then decontaminated for the next person who enters from the grey side.
After work is completed, exit procedures may follow the reverse order from the entry process, depending on the standard operating procedures at the institutions. In general, the hot side shower door is disengaged to allow entry into the shower vestibule. The over-boots, if used, are removed and scrubbed clean. The researcher closes him or herself in the chemical shower, connects to air, and runs the decontamination shower. The shower runs for multiple cycles, which includes at least a several minute cycle of disinfectant and a several minute cycle of water. During the shower cycle time, sponges and brushes are used to clean and scrub the outer suit surfaces, built-in boots on suits, and gloves. At the completion of the shower cycle, the researcher re-enters the grey side where the suit is doffed and hung to dry and PPE are disposed into a biohazard bag. Laboratory clothing is removed and placed into a laundry bag for autoclave sterilization and laundering once removed. The researcher then exits through the personal shower, before putting street clothes back on and exiting the cold side change room.
When the entire entry process is performed uninterrupted and only few supplies are taken in, it can be accomplished in as few as 15 minutes. Uninterrupted exit from the BSL-4 side to cold-side/hallway may take about 20 minutes. Some facilities have gender specific change rooms to avoid delays incurred by waiting for a colleague of the opposite sex. Changing gloves and pressure testing the suit adds another 15 to 30 minutes to the entry process, and waiting to coordinate with coworkers for entry or exit as a team can take longer yet. Depending on the level of activity and number of personnel entering or exiting the lab, a person might have to wait through a cycle of the decontamination shower before entry or exit to/from the hot side.