There is no question that UVC (Ultraviolet light of the 250-260mm wavelength) is a powerful germicide.  Given sufficient intensity, UVC will inactivate pathogens on a surface. But since the intensity depends on contact time and proximity to the light, the question has been how to effectively apply UVC to pathogens moving at 500 fpm through the ducts in an HVAC system. UVC lamps by themselves cannot guarantee sufficient intensity to kill organisms as they move by in the airstream. And while high-efficiency passive filters may capture pathogens, UVC cannot penetrate the dense media, allowing them to remain active. 

For those applications where biological inactivation is important, high-output UVC and a polarized glass media are combined to provide a catch, hold, kill solution. The key for UVC to be effective is contact time and proximity. The Dynamic system captures the biologicals in the airstream on essentially a translucent surface. A scanning parabolic reflector focuses a sterilizing beam of UVC that sweeps the media again and again, to provide the necessary contact time. A cowling keeps the lamp clean and the UVC contained. This is a far more efficient system with less potential for collateral exposure than one that bathes an entire coil or duct section with UVC.