An air treatment system includes a lower cowling configured to be suspended from a ceiling, the lower cowling defining an interior lower cowling surface and configured to be disposable radially outward from and around a fan configured to induce airflow. Further, the air treatment system includes an upper cowling configured to be disposed vertically above the lower cowling and define an interior upper cowling surface. A gap between the interior upper cowling surface and the interior lower cowling surface forms a fluid passageway comprising an intake opening, an exhaust opening, and a chamber. The fluid passageway is contoured to receive airflow from the fan via the intake opening and direct the airflow through the chamber to exit the exhaust opening. Moreover, the air treatment system includes at least one air treatment device secured within the chamber, the air treatment device configured to treat air passing through the chamber.