Extract from Popular Science (July 2001, Page 30):

AK Steel of Middletown, Ohio, will soon begin marketing its new "antimicrobial 
steel" for home heating, ventilation, and AC ducts.  The ducting was approved 
by the EPA in March 2001.
 
The steel is coated with an "antimicrobial compound" produced by Agion 
Technologies of Wakefield, Mass., which contains IONIC SILVER to control 
microorganisms including fungi and yeast.

The company is building a 11,000 SF home in Simi Valley, CA to test its 
product.  The home will be completely equipped with new Ionic Steel coated 
ducting, as well as doorknobs, handrails, faucets, and food preparation 
surfaces covered with the same coating.