What To Do If Your HVAC System Is Contaminated With Asbestos: A Complete Homeowner Guide.

I visited a client’s home where asbestos contamination is present throughout the property. The client has already vacated the home and hired a general contractor, who in turn contracted AVERA Environmental to handle the asbestos abatement. Our scope includes the removal of terracotta tile throughout the basement level, and the 9×9 floor tile with black ACM mastic. After removal, we will also perform a full top-to-bottom decontamination of the entire home to eliminate asbestos particulates.

During the inspection, it became clear that asbestos fibers likely circulated through the HVAC system and reached the upper floors. This happened because the plumber unknowingly broke through ACM flooring while rerouting plumbing, which allowed asbestos material to become airborne.

The client asked how AVERA Environmental would decontaminate the HVAC units. Below is the explanation we should give to ensure clarity and confidence in our abatement process.

How AVERA Environmental Decontaminates HVAC Units During Asbestos Abatement

1. Shut Down & Isolate the System

• The HVAC system is shut off immediately to prevent further circulation.
• All supply and return registers are sealed using 6-mil poly and tape.
• The entire HVAC system is placed under containment as part of the work area.

2. HEPA Vacuuming of All Accessible Components

• Trained asbestos technicians HEPA-vacuum the interior of the return and supply boots, register boxes, and accessible duct surfaces.
• The exterior of air handlers, furnaces, and heat pumps are also HEPA-vacuumed.

3. Detailed Wet Wipe Decontamination

• After vacuuming, all accessible ductwork surfaces, blower compartments, coils (exterior surfaces), and housings are wet-wiped using approved asbestos-removal surfactants.
• This step captures fine residual particulates that a vacuum cannot fully remove.

4. Replace All Filters with HEPA-Rated Units

• Existing filters are removed as contaminated waste.
• The system receives new HEPA or high-efficiency MERV-rated filters as part of the post-cleaning process.

5. Optional: Professional Duct Cleaning with Negative Air Machine
If required or requested:

• A specialized negative-air duct cleaning system is attached to the main duct run.
• Rotating brushes and HEPA-filtered vacuums perform an enhanced internal duct cleaning.
  (This is typically an add-on but recommended for heavy contamination.)

6. Final Clearance & System Restart

• After cleaning, the HVAC remains sealed until final air clearance testing is completed in the home.
• Once the environment passes, the system can be safely restarted.
• Registers are unsealed and the client receives documentation of the HVAC decontamination.