Provided is an apparatus, system, and method for evaluating and adjusting the effectiveness of ultraviolet light disinfection of areas such as hospital rooms or other areas. Provided in certain example embodiments are UV dosimeters adapted to visually indicate when they have been exposed to light in the UV C band range at a predetermined fluence level, the UV dosimeters being removably adhesable to surfaces in the room or area. Provided is an inexpensive, easy-to-use UV dosimeter and accompanying iterative process for optimizing UV disinfection parameters for a given area, including light source location(s), duration, and power level, and then recording that information for future use in connection with that area.
