Whenever a public hearing is upon an application for a variance, exception, conditional use permit or other similar permit, or for the revocation or modification of the same, then and only then, notice of the time and place of the public hearing shall be mailed, postage prepaid, not less than five days prior thereto to all persons whose names and addresses appear on the last adopted tax roll of the County, or are known to the City Clerk, as owning property within a distance of not less than 300 feet from the exterior boundaries of the area actually occupied or to be occupied by the use which is the subject of the public hearing.