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Can Mold Grow in Ductwork?


Mold can grow in ductwork and form colonies wherever there’s a source of moisture and nutrients. It’s found naturally outdoors and indoors. When mold forms on bathroom or basement walls, it’s easily seen and often easy to clean before it becomes widespread. But when mold is present in ductwork and other parts of your HVAC system, it’s hidden in remote areas. It can grow uninhibited, spread throughout the duct system, and circulate in the air you breathe.

Why Ductwork Is Conducive to Mold Growth

Moisture collects in air ducts due to higher humidity levels. As warm air is absorbed through the evaporator coil, condensation forms, and water droplets can reach the ductwork. If water doesn’t evaporate, ducts can become an environment where mold colonies can grow. The spores will use dead skin cells, dirt, and dust, which are commonly found in air ducts, as food sources.

Can Mold Grow in Ductwork and Be Harmful?

Mold can release toxins that affect your health. People with allergies, asthma, and respiratory problems are most at risk. Black mold is especially concerning; this toxic fungus, also known as Stachybotrys chartarum, appears slimy and wet and has a dark blackish, greenish-black, or gray color. It grows in air vents and other porous surfaces. 

Signs of Mold in Your Ductwork

Poor duct maintenance can lead to excessive moisture and dust that enable mold to grow. The sooner the issue is resolved, the better; you can prevent an extensive infestation or long-term health consequences. Call a professional if you notice these signs of mold in your ductwork:

  • Health Symptoms: Fatigue, headache, nausea, coughing, sneezing, itchy eyes, nasal congestion, and skin irritation are common signs of exposure to mold mycotoxins. Long-term respiratory issues and lung disease can also occur. Breathing in black mold spores can lead to brain fog as well.
  • Musty Odors: Have the system checked for mold if there’s a strong musty odor when the HVAC unit is running, whether it’s everywhere in your home or just in one room. Black mold often has a musty, earthy smell similar to rotting leaves.
  • Dust or Spots Around the Air Handler/Vents: If there are dark spots or dust around the air vents or the air handler, try to clean them with a solution of 1 part bleach to 3 parts water. This only remedies the mold you see, not the potential growth in air ducts.

Call a Professional to Handle Mold Growth in Ductwork

Remember, attempting to clean mold yourself risks exposure to it. You can develop a rash or skin irritation just by touching some molds. While mold removal products are available in stores, the wrong method can spread the mold and worsen the problem.

A trained technician is not only equipped to safely and effectively eliminate mold. They can determine its causes. For example, an oversized AC unit will cool your home too fast and not remove enough humidity. Or, if your AC is set at too low a temperature, condensation can form as cold air mixes with warm air. Moisture can then form inside and outside the vents. Warm and cold air can also mix in a leaky duct system, creating moisture that allows mold to grow.

Mold can grow in ductwork unless steps are taken to prevent it. To reduce your risk of mold, a technician can:

  • Install a dehumidifier in your HVAC system.
  • Replace clogged air filters.
  • Clean dirty condenser coils.
  • Find the ideal temperature setting on your thermostat.
  • Seal leaks in your ductwork.
  • Insulate air ducts to prevent condensation.

When performing a mold inspection, a professional will first identify the source of the mold, such as a water leak, and fix it. HVAC technicians employ advanced testing methods to determine the exact type of mold, its concentration, and its possible cause. Wearing protective clothing, using specialized tools and equipment, and following the right protocols, they can safely clean air ducts of mold and retest to verify the success of a remediation service.

Contact Monarch Home Services Today

We provide duct cleaning and other indoor air quality services in Bakersfield, Fresno, and throughout Central California. During maintenance, our technicians can clean drip pans and address sources of moisture and condensation. Other solutions include installing UV lamps, sealing ducts, and improving air filtration, while the Air Scrubber Plus combines UV light with advanced air filtration to purify indoor air. To learn more and receive your free quote, call (661) 215-6428 today.

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