UV germicidal lights are actually extremely simple in their design and operation. The lamps are installed in the ductwork of an HVAC system, typically right by the air handler to ensure that all of the air passing through the system is treated. The lamps emit light rays on the ultraviolet spectrum. The UV radiation, which is completely safe for everyone in the house, including pets, and is completely confined to the ducts, proves devastating for biological pollutants.