The present invention provides for a filter system having a catalyst filter configured for placement in a filter housing. The catalyst filter has a first band and a second band of material. Each band has a length of material extending in a longitudinal direction. Each band has a first wall and a second wall, each wall facing in an opposite direction from the other wall. A portion of each first wall is coated with a catalyst material, which receives light emitted by a light source to break down contaminants passing in air through the housing and over the catalyst material. Each of the first and second bands extends continuously along its longitudinal axis traversing the catalyst filter without being intersected by other structure of the catalyst filter. The first and second bands of material diverge relative to each other across the catalyst filter. The first wall of each band is optically exposed to light from the light source. Such light from a light source at least partially disposed to emit light between the first and second bands of material is received on the catalyst material of the first walls of both the first and second bands of material without being at least partially blocked by one of the first and second bands or other structure of the catalyst filter.