An air purification system, includes a UVC light source arranged within an internal space of a purification chamber and adapted to irradiate the internal space with UVC, an airflow system arranged to introduce environmental air from outside of the air purification system into the internal space of the purification chamber and expel purified air from the purification chamber back outside of the air purification system, and a light blocking system arranged to block a substantial amount of the irradiated UVC from emitting outside of the air purification system, the light blocking system comprising a high-air-flow open structure mounted in the airflow system of the purification chamber, wherein the open structure comprises a front surface, rear surface and a thickness, wherein the front and rear surfaces have a plurality of open areas connected through the thickness, and wherein at least one of the plurality of open areas is of a size with respect to the thickness to block light from traversing the thickness when an angle of incidence is less than approximately 10 degrees.