Mass. Gen. Laws ch. 143 § 21D
The owner, lessee or mortgagee in possession of any multiple dwelling of ten or more units shall equip such dwelling with an auxiliary emergency lighting system independent of the conventional lighting system, and lighted signs indicating both a primary and secondary means of egress by a diagram or symbol so as to assure recognition by all persons, regardless of their English-speaking ability.
The commissioner shall make and promulgate, and from time to time may alter, amend and repeal, rules and regulations relative to the standards, installation and maintenance of emergency lighting systems and exit signs required by this section. Such regulations shall include but not be limited to specifications with respect to the degree of illumination and the location of emergency lighting systems, and the degree of illumination and the location of, and the symbolism in, exit signs.
Mass. Gen. Laws ch. 143, § 21D