§ 621. State aid; public health emergencies. If the state commissioner or a county health department or part-county department of health or municipality, with the approval of the state commissioner, determines that there is an imminent threat to public health, the department shall reimburse counties or municipalities at fifty per centum for the cost of emergency measures as approved by the department and subject to the approval of the director of the budget, except that aerial spraying for mosquitoes on state land shall be reimbursed at one hundred per centum, within amounts appropriated. Such funds shall be made available from funds appropriated for public health emergencies, only to those counties or municipalities, which have expended all other state aid which may be available for related activities and have developed measures to adequately address the emergency. Reimbursement is conditioned upon availability of appropriated funds. For purposes of this section, "municipality" means a health department of a city that is not located in a county or part-county health district or a county in which the legislature has the powers and duties of a board of health of a county or part-county health district and cities with a population of over one million persons.