Any story, any portion of the finished ceiling of which is either below the average curb level in front of the building or below the average finished exterior grade around the perimeter of the building, shall be designated as cellar area and may be used for utility purposes only, such as the location of motors, heating equipment, cooling equipment and any and all other mechanical devices necessary for the operation of the building for dead storage of merchandise inventory, supplies, files, records and the like, for parking of tenants' automobiles, but may not be used as an area in which persons may live, sleep, work or congregate, nor may such area be used for restaurant, commissary, kitchen, recreation or entertainment purposes.