Air filtration system

An air filtration system comprising:

• an occupied space from which air is taken in;
• an air plenum from which air is returned to the occupied space;
• an extruded frame with an associated grille proximal to the occupied space, the extruded frame configured to be inserted within a structure associated with the air plenum, the structure being a drop ceiling, a solid ceiling or a wall separating the occupied space from the air plenum;
• a pleated filter positioned adjacent the grille, the pleated filter dimensioned for entrapping particles in the 1 to 3 micron size,
• an ultraviolet lamp for emitting UV-C light positioned adjacent the pleated air filter so as to irradiate airborne particles that may pass through the pleated filter prior to flowing into the air plenum from the occupied space, and in particular to irradiate particles associated with microorganisms, including viruses,
• an electrical switch and associated electrical ballast for controlling operation of the electrical lamp and so as to ensure that the lamp is not energized when the air filtration system is being installed or service;
• and
• means for securing the extruded frame of the air filtration system to the structure;
• wherein the grille, the pleated filter, and the ultraviolet lamp form proximal and parallel layers between the occupied space and the return air duct.