Emergency escape openings. Required emergency escape openings shall
be maintained in accordance with the code in effect at the time of
construction, and the following. Required emergency escape and rescue
openings shall be operational from the inside of the room without
the use of keys or tools. Bars, grilles, grates or similar devices
are permitted to be placed over emergency escape and rescue openings
provided the minimum net clear opening size complies with the code
that was in effect at the time of construction and such devices shall
be releasable or removable from the inside without the use of a key,
tool or force greater than that which is required for normal operation
of the escape and rescue opening.