The acquisition of any land or interest therein pursuant to this act,¹ the planning, acquisition, establishment, development, construction, improvement, maintenance, equipment, operation, regulation, protection and policing of airports and air navigation facilities, including the acquisition or elimination of airport hazards, and the exercise of any other powers herein granted to municipalities and other public agencies, to be severally or jointly exercised, are hereby declared to be public and governmental functions, exercised for a public purpose, and matters of public necessity; and in the case of any county, are declared to be county functions and purposes as well as public and governmental; and in the case of any municipality other than a county, are declared to be municipal functions and purposes as well as public and governmental. All land and other property and privileges acquired and used by or on behalf of any municipality or other public agency in the manner and for the purposes enumerated in this act shall and are hereby declared to be acquired and used for public and governmental purposes and as a matter of public necessity, and, in the case of a county or municipality, for county or municipal purposes, respectively.