A biosafety level-4 (BSL-4) lab may look like an ordinary building from the outside, but these buildings are anything but ordinary. They are designed and constructed by experts so that nothing gets in or out that isn't supposed to, not even something as tiny as a bacterium or virus.
BSL-4 design features include the following:
- All seams, joints and doors are sealed to make the building airtight. You cannot open a window in a BSL-4 lab. Air does not flow in or out under the doors.
- Air is pumped in and out of the building through a filtration system that catches even the tiniest microscopic particles, bacteria and viruses included.
- All air ducts are welded stainless steel and tested to be airtight.
- Inside many BSL-4 facilities, the laboratories are surrounded by buffer corridors that help protect the labs in the event of a bombing attack from outside.
- Features such as airlocks, fumigation chambers, disinfectant "dunk tanks" and waste water treatment systems ensure that absolutely everything that leaves a BSL-4 lab is decontaminated.
