Reading building codes is fun. The following links are provided for your enjoyment with the realization that they contain bureaucratic language and PDF files.
Means Of Egress
This is an interesting article dealing mainly with fire and poor means of egress but it contains this interesting quote:
In addition, threats other than fire, e.g., chemical attacks, gun wielding terrorists and similar threats, directly challenged the time-based people movement assumptions. Risk assessments are now per formed on major public and iconic buildings and additional, non-traditional measures are considered to meet their safety needs.
Then there is OSHA. It is for employees, but there are a lot of employees trapped by such methods. I am a visitor in a lot of industrial facilities. OSHA is just as strict on visitor safety. I can guarantee that if you are a manager in an industrial facility and they find a locked or blocked exit door you will be notified in an unpleasant way.
The code is at this link. It is an 800+ page pdf but the applicable information starts at page 146 in the document and 61 in the pdf.
Some interesting pull quotes:
1910.36 (a)
(1) An exit route must be permanent. Each exit route must be a permanent
part of the workplace.
(3)(d) An exit door must be unlocked.
(1) Employees must be able to open an exit
route door from the inside at all times
without keys, tools, or special knowl-
edge. A device such as a panic bar that
locks only from the outside is per-
mitted on exit discharge doors.
And my favorite from a quick read:
(3) An exit route door may be locked
from the inside only in mental, penal,
or correctional facilities and then only
if supervisory personnel are continu-
ously on duty and the employer has a
plan to remove occupants from the fa-
cility during an emergency.