The laws related to emergency lighting units in Chicago are found in a mixture of regulations, as follows:
NFPA 101, Chapter 7.
OSHA 1910.37(b) 1 and 2.
Municipal Code of Chicago - Ch 13-160
The Chicago Municipal Code is available online here: http://www.amlegal.com/codes/client/chicago_il/.
Fire Safety Learning Center
Articles and other information related to fire safety equipment and procedures in Illinois.