In the event an emergency is found to exist by the board which, in its judgment, requires the making, changing, renewal, or extension of a rule, regulation, or order without first having a hearing, such emergency rule, regulation, or order shall have the same validity as if a hearing with respect to the same had been held after due notice. The emergency rule, regulation or order permitted by this section shall remain in force no longer than forty-five (45) days from its effective date, and, in any event, it shall expire when the rule, regulation, or order made after due notice and hearing with respect to the subject matter of such emergency rule, regulation or order becomes effective.