Sanitizing and Soot Set are optional treatments offered by Enviro Fresh Duct Cleaning. Sanitzing agents and Soot Set are applied with special fogging machines and get to those hard to reach places like seams and corners.  Sporicidin sanitizer is approved by the EPA for use on nonporous duct materials such as sheet metal. Sporicidin is safe and effective. It treats bacteria, mold, viruses, and other micro organisms that may be living in the ducts.  It is used in hospitals and food processing plants. Sporicidin has a residual effect that lasts about 6 months. Sanitizing is an extra step at providing the cleanest HVAC system possible and may be of added help to allergy and asthma sufferers.