N.Y. Second Class Cities Law § 153
In case of great and imminent peril to the public health of the city, by reason of impending pestilence, it shall be the duty of the commissioner, with the sanction of the common council, if it be practicable to convene that body for prompt action, or if not, when approved by the board of estimate and apportionment, to take such measures, and to do, order, or cause to be done, such acts, and to make such extraordinary expenditures in excess of the sum appropriated to the department of health from moneys made available pursuant to section seventy-six of this chapter or section 29.00 of the local finance law, for the preservation and protection of the public health, as he may deem necessary and proper. Such peril to public health shall be deemed to exist only when and for such period as the commissioner and the board of estimate and apportionment, by unanimous vote, shall determine.
N.Y. Second Class Cities Law § 153