US Patent 7112742 Method of improving interior environment and grounding electrode device

To maintain an interior environment in an environment in which negative ions are abundant, and to stably maintain the environment at a higher level with maintaining an efficacy of the charcoal included in a paint containing a charcoal powder applied to a wall face in a room, a floor face in the room is formed by an insulator and the wall face is made to have a grounding electric potential by connecting it to a grounding electrode buried in a ground according to a method of the invention. The grounding electrode device includes a main body formed in a bottomed tubular body by a metal, and a charcoal and a catalyst are accommodated in the main body.