Notwithstanding the provisions of N.H. Rev. Stat. § 200:36, before employing any person as a school bus operator, the town or city governing body which pays for such transportation shall require that such person submit a certificate signed by a licensed physician setting forth the physician’s findings as a result of the examination to determine the physical condition of drivers in accordance with the requirements of 49 C.F.R. § 391.41-391.49. Such certificate shall be submitted to the local governing body prior to the commencement of such employment, which shall retain a copy of such certification. Every 2 years thereafter, either prior to the commencement of the school year or prior to the reemployment of such person as a school bus operator, such governing body shall require submission of a like certificate, except that school bus operators attaining the age of 70 shall be required to undergo an annual examination and to submit a certificate annually.