The purpose of this guidance is to supplement the March 14, 2002 letter from Marcia Mulkey, former Office of Pesticide Programs Office Director at the EPA, which identified several Agency concerns regarding the use of Air Duct Sanitizing sanitizers, disinfectants, and other types of antimicrobial products to treat the surfaces of heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems, typically as part of air duct maintenance or cleaning. The intent of the supplemental guidance is to ensure that users, applicators, and registrants are only using products labeled for use in HVAC&R systems. The Agency is providing this supplemental information because HVAC&R systems represent a unique use site and the Agency is concerned about potential risks to applicators and building occupants that may be associated with the use of antimicrobial products in such settings.

The Agency believes that certain types of Air Duct Sanitizing antimicrobial products not registered for use in HVAC&R systems are being used in a manner not authorized by the label and not assessed by the Agency as part of the pesticide registration or amendment process. Although the directions for use of most registered sanitizer and disinfectant products permit use on hard non-porous surfaces, because of the uniqueness of HVAC&R systems, such directions for use do not include use on or in HVAC&R components or surfaces unless such HVAC&R use is specifically included on the label.