hefa, higher efficiency particulate air filters. they filter out particles, and think viruses. >> air goes through the hepar filter twice before being released to the outside world. liquid waste is treated in a different way. >> these walls have double wall piping. we have a sample here. >> reporter: what is the point of the pipe within the pipe. >> if the inner pipe that the liquid is flowing through develops a leak, it would flow into the outer pipe and become tamed. there is senses there alerting the building automation system. there would be an alarm. >> waste is disinfected, and it flows to the tanks, where they are heated at 120 degrees for 60 minutes, to kill off anything that might remain. and then, of course, there's the human factor. >> i'll tell by the positive pressure suit that we wear in the bsl-4. and i'll hopefully get you into this. >> reporter: okay, i've got my right? >> not quite. you have jewellery on, rings, diamond rings can compromise the gloves. off. >> you see the air drops. when the air comes in through th