Introducing ultraviolet (UV) light to activate a light sensitive chemical compound applied to interior portions of footwear alters the environment inside a shoe or other footwear to destroy microorganisms or inhibit their growth. Visible light can also be used to prevent further microorganism growth. Introducing forced air flow through the footwear removes dampness in and thereby deodorizes the footwear. A preferred embodiment comprises an adjustable shoe tree equipped with a UV germicidal light source and electronic safeguards that prevent appreciable leakage of UV radiation outside the shoe.