Abstract: An air treatment system includes a housing defining a disinfection chamber disposed between an air intake and an air discharge, and a blower in the disinfection chamber adapted to move air through the disinfection chamber along a nominal flow axis. A pair of LED emitters in the disinfection chamber each generate a beam of UV-C light along a beam center axis having a spacial distribution of direct UV-C light characterized by major and minor axes, with the beam center axis of one emitter being generally perpendicular to the nominal flow axis and generally perpendicular to the other beam center axis, the generated spacial distributions of direct UV-C light at least partially overlapping one another within the disinfection chamber, and a reference plane containing one LED emitter's beam center and major axes is generally perpendicular to another reference plane containing the other LED emitter's beam center and major axes.