In the case of public places consisting of a single room, the provisions of this law shall be considered met if a portion of the room is reserved and posted as a designated smoking area. No public place, restaurant or County workplace, other than a cocktail lounge, tavern, or bowling center, shall be designated as a smoking area in its entirety. If a cocktail lounge, tavern, or bowling center is designated as a smoking area in its entirety, this designation shall be posted conspicuously on all entrances normally used by the public.