The governing body of any county or city having an emergency medical services zone or district created under the provisions of § 32.1-111.14:2, prior to June 1 of any calendar year, may alter the boundaries of such emergency medical services zone or district for the purpose of excluding an area of any such emergency medical services zone or district that is also within the boundaries of a sanitary district providing emergency medical services or under contract to a sanitary district providing emergency medical services. Any area excluded from an emergency medical services zone or district as provided by this section shall not be subject to the levy set forth in § 32.1-111.14:2 for the year such area is excluded.