Mold Remediation Blog

Types Of Mold Found In Air Ducts

illustration of a homeowner inhaling toxic mold from air ducts

Most homeowners at one point or another find themselves trying to counteract the growth of mold in the home. Mold growth can become a serious issue in areas of the home that are susceptible to moisture build-ups, such as bathrooms, basements, crawl spaces, and air ducts. 

The naturally cool and dark environment of air conditioners and air ducts provides an exceptional breeding ground for many different types of mold. 

While some types of mold pose more of an increased risk than others, all necessary steps should be taken to eliminate every type of mold in the home. 

Air duct maintenance can be easy to forget about and more often than not, homeowners who have not had their air ducts cleaned in the last 3-5 years could have mold growing throughout the system. 

Let’s talk about the most common types of mold found in air ducts, identification characteristics, and the health risks.


When we find mold in air ducts and HVAC systems, Alternaria is usually the prime suspect. Alternaria thrives in extremely moist environments that are rarely, if ever, completely dry. 

Alternaria can be identified by its brown or black colorations with an unappealing velvet-like texture. Exposure to Alternaria usually does not directly cause health problems in healthy individuals, although those with a weakened immune system are at risk of developing various ailments. 


Another one of the more common and dangerous types of mold that finds its way into many homes is Acremonium. Acremonium is highly toxic and should be taken extremely seriously once identified. Extended exposure to Acremonium has recently been proven to be a causation of Mycetoma, an extreme skin infection that poses serious health risks. 

On top of this, Acremonium is considered a carcinogen and, as we know, carcinogens have the potential to affect brain function.  Acremonium takes the form of a white powdery substance, making it extremely easy to identify


Chaetomium typically clings itself to walls in moist environments such as basements and crawl spaces, but air ducts are not out of reach. It can most commonly be identified by the musky odor, a clear indicator that Chaetomium has become a problem.

Unlike other types of mold, Chaetomium can change color over its lifespan, making it hard to identify with just your eyes. The most common color Chaetomium grows in is brown with a cotton-like texture.


When it comes to identifying various types of mold, Aspergillus doesn’t make it easy. Aspergillus will most commonly grow in shades of green, yellow, or white and is one of the most common types found in unclean air ducts. 

Breathing in Aspergillus spores does not pose any serious health risks to those with healthy immune systems.


Mucor is one of the most serious forms of mold in terms of health risks and should be taken very seriously, especially for those with underlying health conditions. 

Exposure to Mucor can cause violent asthma attacks and difficulty breathing in healthy individuals, with worsened symptoms for those with respiratory illness or disease. 

Mucor grows in thick patches in shades of white or gray and is commonly found in areas of the air duct system that gathers moisture.


Stachybotrys, also known as “black mold,” typically grow in areas where there is visible water damage but can be prevalent in air ducts. Stachybotrys is extremely common and can be hard to contain due to its rapid growth rate. 

Stachybotrys can be identified by, you guessed it, its dark black or brown color. It has been known to cause allergic reactions in some, so it should not be overlooked.


When it comes to air ducts, HVAC systems, and air conditioners, having a clean air filter is imperative. Without a clean filter, you do not have clean air. Trichoderma is one of the most common types of mold found growing on old air filters. Trichoderma can spread to other areas of the home very easily and has a spore-like presentation. 

Trichoderma grows in shades of white or green, adding to its overall grotesque appearance

Found Mold In Your Home? Give Us A Call!

If you have visibly seen mold growing in your home, it’s unfortunately already too late. Mold could have already spread within the home, and the breeding ground could very well be your air ducts! 

Here at Valor Mold, we specialize in mold cleaning services and can get your air ducts back in tip-top shape!

Give us a call at (703) 897-7121 to get started today! 

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