Antimicrobial and encapsulation services, with the evidence and the EPA registration requirements stated plainly.
This category needs a caveat before it needs a comparison table, because sanitizing is the service most likely to be sold to people who do not need it, at the moment they are least equipped to evaluate the claim.
The core principle is that antimicrobial treatment is not a substitute for source removal, and applying it to a system that has not been physically cleaned is close to useless. Biological growth needs moisture and a nutrient substrate. The nutrient substrate is the accumulated organic debris on the duct surface. Spraying a biocide over that debris kills what it contacts and leaves the food supply in place, which is why treated-but-uncleaned systems regrow. The correct sequence is always mechanical cleaning first, moisture source identified and corrected second, and chemical treatment only if a specific condition still justifies it.
The second principle is regulatory and it is a genuinely useful filter. In the United States, any product applied to a surface with the claim that it kills or inhibits microorganisms is a pesticide and must be registered with the EPA, and it must be applied in a manner consistent with its label. A great many products are registered for use on hard non-porous surfaces but are not registered for application inside operating HVAC ductwork, and applying them there is both a label violation and a real exposure question for the occupants. Ask for the product name and the EPA registration number, then ask specifically whether the label covers HVAC duct interiors. A contractor who cannot answer that in one sentence should not be spraying anything into your air system.
Fibreglass duct board and internally lined duct add a further complication. Porous insulation cannot be surface-cleaned to a defensible standard once it is genuinely contaminated, and biocides do not penetrate it usefully. The honest options are encapsulation, where an approved coating seals the surface, or replacement of the affected section. Encapsulation over active moisture or unremoved growth is a cosmetic treatment with a limited life.
Where this service is genuinely warranted, mostly in the humid Gulf, Florida and coastal Carolina markets in this directory, it is warranted as the last step of a properly sequenced job. The filters here emphasise certified technicians and camera verification because you are being asked to pay for something invisible applied to a surface you cannot inspect.
We are still building out this part of the directory. If you know a company that belongs here, tell us.
Local pricing, local access conditions and the companies that actually cover each metro.