The Board shall hold a public hearing on all proposed actions including administrative appeals, proposals for variances, exceptions and industrial uses. Notice shall be given at least fifteen days in advance of the public hearing in a newspaper of general circulation in the City. Any party may appear in person at the public hearing, or by agent or attorney. The owners of property within, contiguous to and directly across the street from the parcel or parcels which are the subject matter of any proposed action, and also the persons proposing or requesting such action, shall be notified of such public hearing in writing by ordinary first class mail sent not less than twelve days prior to such hearing. The secretary of the Board shall, prior to the public hearing, certify by writing filed with the Board that such notice has been timely given.