Did not know that about the ventilation ducts.
One of the ones I worked was ok because the whole project team worked in the scif.
On another project, I’d routinely be the only person in the room. I did not like that.
Interesting thing. When Northrup Graumman bought TRW, they closed our offices in Sunnyvale, CA. The main building for classified work was totally torn down because it was cheaper to do that than try to take out the scifs.
Btw—thanks for mentioning SCIFs in contractors.
The same issues apply—we do not want rogue contractors answering only to rogue bureaucrats.