Did you know that musty smell you associate with mold is actually from wet building materials, and not mold? Therefore, mold grows where there is moisture, so you still would probably find mold in the following places:

  1. Wet building materials
  2. Wet insulation
  3. Improperly installed plumbing
  4. Window frames
  5. Damp wallpaper. We could go on.

Mold belongs outdoors in its natural environment, although we do find mold indoors.

What you smell is what we call microbial volatile organic compounds (mVOCs). These odorous compounds, often described as a musty smell, are often the first signal of mold growth. So the mold may start releasing these compounds even before you can see any mold growth.

What kind of mold you would find in your house?

Molds are fungi that grow on moist, warm organic matter. Because it is quite rare to find Stachybotrys, which is considered “black mold,” in your house. We will discuss the 4 genus of mold that are commonly found indoors though there are over 100,000 species of mold.

Here’s a rundown:



Alternaria is typically found on plant tissue, decaying wood, and foods. Therefore it can grow thick colonies which are usually green, grey, or black. So you may find it where water condenses on window frames, bad shower installations, or the drip pan of an AC unit.

Alternaria spores are one of the most common & potent indoor and outdoor airborne allergens. Additionally, Alternaria sensitization has been determined to be one of the most important factors in the onset of childhood asthma.



You might find the green, grey, or black growth of Aspergillus in your house on damp walls, wallpaper, drywall, carpet and mattress dust, upholstered-furniture dust, HVAC insulation, furnace filters and fans, humidifier water, and decomposing wood. For folks with weakened immune systems, breathing in Aspergillus spores can cause an infection in the lungs or sinuses which can spread to other parts of the body. And may include hearing problems or even hearing loss. A species of Aspergillus is used to make sake. Who thinks of this stuff?

Alternaria and aspergillus are those molds typically found seeking breeding ground in your home. Aspergillus may be mistaken for the black mold Stachybotrys due to its color.



Because Cladosporium likes to live in wet corners you will find it along with the caulking. Or on the tiles in your shower or bath and on shower curtains, in insulation, window frames. Similar to the other molds we’re talking about here, it’s white, grey, green, or black. The airborne spores of Cladosporium species may cause infections in the sinuses and lungs, or skin and toenails.


Penicillium CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1774920

It may be the green fuzzy stuff you’ll find on a sandwich. Or on paint, in carpet, wallpaper, interior fiberglass duct installation. If penicillium sounds familiar it is because some members of this genus are used to produce penicillin. And other species are used in cheesemaking but don’t try it at home. There are like, 200 species of penicillium. So it’s kind of hard to track the exact species down for your next homemade batch of Camembert.

Health effects:

Common symptoms of mold allergies include skin irritation, eye irritation, wheezing, and nasal stuffiness. Which most of us, unfortunately, experience as allergy symptoms that show up with spring weather. Immune-compromised people and people with chronic lung illnesses, such as obstructive lung disease, may get serious infections in their lungs when they are exposed to mold. Mold does not react the same with everyone, so some may experience little or no symptoms, while others have severe reactions.

So, if you think you are getting that musty smell, and you can feel it, what’s next?

Next: Mold? How did we get to this point, and what should we do?

About Lisa McIntyre

Lisa McIntyre has always resided in the Greater Cincinnati and Northern Kentucky. She graduated from University of Cincinnati with a degree in Applied Science. Ultimately, her passion for science and teaching came to fruition after her husband requested her assistance in developing Dry Effect Restoration Services. She was able to develop her knowledge, degrees and certifications further in many indoor air quality associations and organizations. Thus allowing her to educate Realtors and Insurance Agents on the damages that many common indoor air quality irritants and water bacterial growths can lead to in ones home or business. Over 10 years later she’s glad to have taken the leap of faith to assist her husband what seemed to be a fun project into a lifetime achievement and to see the individuals she teaches prosper from their newly found knowledge.