A repair guy was selling me on a new furnace today, and one of the options was a fancy filter system. Instead of the usual air filter, there is a filter with a big UV light behind it like this one. The idea is that the UV light will kill germs and allergens so that they aren't sent through the central heating system. They claim:
ULTRA-VIOLET LIGHT TECHNOLOGY is a proven, economical, and effective means of controlling Microbial Pathogens. Pathogens are sub-micron organisms that fall in the Fungal, Bacterial and Viral categories. They are too small to be captured by standard filtration methods.
Does putting a UV light in the ductwork like that work?