A photocatalytic oxidation system comprising a housing having a first cell panel and a second cell panel each comprising a photocatalytic material, a UV bulb disposed within the housing, and a first reflector, wherein the housing comprises: a proximate end panel; a distal end panel, the housing having a longitudinal direction extending from the proximate end panel to the distal end panel; an upper panel connected to and extending longitudinally between top sides of the proximate end panel and the distal end panel; a lower panel connected to and extending longitudinally between lower sides of the proximate end panel and the distal end panel, the lower panel being spaced from the upper panel; the first cell panel is connected to and extends longitudinally between a first side of the proximate end panel and a first side of the distal end panel, and extends vertically between a first side of the upper panel and a first side of the lower panel; the first cell panel comprises a first plurality of apertures and an inner surface, the first plurality of apertures and the inner surface are coated with the photocatalytic material; the second cell panel is connected to and extends longitudinally between a second side of the proximate end panel and a second side of the distal end panel, and extends vertically between a second side of the upper panel and a second side of the lower end panel; the second cell panel comprises a second plurality of apertures and an inner surface, the second plurality of apertures and the inner surface are coated with the photocatalytic material; an interior cavity is bounded by the proximate end and distal end panels, the upper and lower panels, and the first and second cell panels; the elongate UV bulb is positioned inside the cavity and has a center axis that is parallel with the longitudinal direction; and characterized in that the first reflector protrudes inward into the interior cavity from an inner surface of the upper panel and is elongated in the longitudinal direction as an inwardly convex longitudinal trough configured to reflect ultraviolet radiation emitted radially from the elongate UV bulb toward the first plurality of apertures and the inner side of the first active cell, as well as toward the second plurality of apertures and the inner side of the second active cell. the housing comprises: a proximate end panel; a distal end panel, the housing having a longitudinal direction extending from the proximate end panel to the distal end panel; an upper panel connected to and extending longitudinally between top sides of the proximate end panel and the distal end panel; a lower panel connected to and extending longitudinally between lower sides of the proximate end panel and the distal end panel, the lower panel being spaced from the upper panel; a proximate end panel; a distal end panel, the housing having a longitudinal direction extending from the proximate end panel to the distal end panel; an upper panel connected to and extending longitudinally between top sides of the proximate end panel and the distal end panel; a lower panel connected to and extending longitudinally between lower sides of the proximate end panel and the distal end panel, the lower panel being spaced from the upper panel; the first cell panel is connected to and extends longitudinally between a first side of the proximate end panel and a first side of the distal end panel, and extends vertically between a first side of the upper panel and a first side of the lower panel; the first cell panel comprises a first plurality of apertures and an inner surface, the first plurality of apertures and the inner surface are coated with the photocatalytic material; the second cell panel is connected to and extends longitudinally between a second side of the proximate end panel and a second side of the distal end panel, and extends vertically between a second side of the upper panel and a second side of the lower end panel; the second cell panel comprises a second plurality of apertures and an inner surface, the second plurality of apertures and the inner surface are coated with the photocatalytic material; an interior cavity is bounded by the proximate end and distal end panels, the upper and lower panels, and the first and second cell panels; the elongate UV bulb is positioned inside the cavity and has a center axis that is parallel with the longitudinal direction; and characterized in that the first reflector protrudes inward into the interior cavity from an inner surface of the upper panel and is elongated in the longitudinal direction as an inwardly convex longitudinal trough configured to reflect ultraviolet radiation emitted radially from the elongate UV bulb toward the first plurality of apertures and the inner side of the first active cell, as well as toward the second plurality of apertures and the inner side of the second active cell.