Fiberboard and internally lined ducts are commonly used in HVAC systems for their insulation and sound-dampening qualities. These types of ductwork are often lined with fiberglass materials to help maintain indoor temperature and reduce noise. While they may offer benefits for efficiency and comfort, there’s a hidden risk homeowners should be aware of—fiberglass exposure.
What Is Fiberboard and Internally Lined Ductwork?
Fiberboard ducts are made of compressed resin-bonded inorganic glass fibers. Internally lined ducts, on the other hand, are sheet metal ducts with a layer of fiberglass insulation glued to the interior. These duct types are frequently used in residential and commercial buildings for thermal control and energy savings.
The Risk: Fiberglass as a Carcinogen
Fiberglass is made from extremely fine strands of glass. Over time, due to wear and tear, age, or improper cleaning, this material can begin to break down. When the duct system is disturbed—or if the fiberglass liner starts to degrade—tiny fibers can become airborne. Once in the air, they may circulate throughout your home, where they can be inhaled.
The U.S. Department of Health and Human Services classifies fiberglass as a possible human carcinogen when it is inhaled in airborne form. Prolonged exposure may lead to respiratory issues, skin irritation, throat discomfort, and in rare cases, could increase cancer risk.
Signs of Deteriorating Fiberglass Ducts
- Dusty vents despite regular cleaning
- Itchy skin or eyes after the HVAC runs
- Unusual odors from vents
- Increased allergy or asthma symptoms indoors
- Visible fiberglass fibers near vent openings
Why Professional Duct Cleaning Matters
Regular air duct cleaning is essential—especially for homes with fiberglass-lined systems. A professional duct cleaning company will:
- Use a power vacuum truck so recontamination within your home doesn’t take place
- Inspect for damage to the internal lining
- Recommend safe sealing or replacement if deterioration is found
- Help maintain healthier indoor air quality
What You Can Do
If your home has fiberboard or internally lined fiberglass ducts:
In Summary
Fiberglass-lined duct systems may save energy, but they also come with a health risk if not properly maintained. When fiberglass becomes airborne, it can be inhaled and is classified as a possible carcinogen. Protect your family’s health by keeping your ducts clean, inspected, and maintained by trained professionals. At Advanced Air Duct Cleaning, your indoor air quality and safety are always our top priority. Contact us today for a free quote!
