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9 Sneaky Signs There Might Be Mold In Your House

Sophia Mitrokostas, Jul. 25, 2018 Insider Health

Most of the time, mold is just a sign that you need to throw out that sandwich at the back of the fridge. However, some household mold can actually be really dangerous.

A small number of mold species produce a substance called mycotoxin, which may lead to breathing problems, headaches, and even permanent neurological damage. Less severe but still aggravating symptoms include a runny nose, sneezing, or an annoying odor, according to the Clinical Microbiology Review.

Here are a few subtle signs that your house could be harboring harmful mold, according to the CDC and the EPA


YOUR AIR CONDITIONING OR HEATING SMELLS WEIRD.One subtle sign of mold is a nasty smell coming from your air conditioner or heating system.

Standalone air conditioning units, in particular, are prime spots for mold growth. They're damp, dark, and frequently exposed to warm temperatures when not in use. Placing an air conditioner in a heated basement or closet during the winter also increases the likelihood of mold developing.

To keep mold from growing in your heating or cooling systems, have them regularly checked out by an HVAC specialist. 

THE GROUT BETWEEN YOUR SHOWER IS DARK. Surprise: that's probably mold. The good news is that it's likely the harmless type.

However, if there was recently a leak in the bathroom plumbing or flooding in an adjacent room, you might be dealing with a more toxic kind of fungus that should only be removed by professionals. Send a sample off to be tested so you can confirm your shower is safe.

YOUR WALLPAPER IS PEELING. While some discoloration and scruffiness are bound to strike your wallpaper eventually, unusual peeling or surface abnormalities like bubbling or cracking can signal the presence of moisture in the wall. Moisture is a reliable precursor to mold.

Keep an eye on your walls and make sure to pay attention to any areas that feel damp or look warped. 

YOU FEEL LIKE YOU HAVE A COLD THAT JUST WON'T GO AWAY. Symptoms of a mold reaction can be as subtle as a perpetually runny nose and sneezing fits. That cold that you just can't seem to shake could actually be a sneaky sign of a mold problem.

Try to notice if your symptoms seem to worsen after spending time in a particular room or immediately after you finish doing laundry in the basement, for example. 

YOU FIND DARK OR COLORED SPOTS ON YOUR WALLS. Mold can appear in many shapes, textures, and colors. It can look like anything from green, dripping slime - definitely something you'd notice - to an innocuous-looking grey fuzz. If your walls are coming out in spots, it's worth double-checking that there isn't a leak in the pipes or uncontrolled humidity in the room.

YOUR ASTHMA MYSTERIOUSLY WORSENS.  If you have a pre-existing breathing problem that seems to flare up after long periods at home, mold could be the culprit.

Most species of household mold won't bother people without breathing issues but can aggravate asthma in individuals who already suffer from the condition. Consider scheduling a doctor's appointment and a mold inspection if your breathing problems seem to worsen without a clear cause.

THERE IS A MUSTY ODOR. If things in your home are suddenly smelling a bit mustier than usual, even after cleaning all the usual suspects, you could have a mold problem on your hands.

One clue that the funky odor in your home is mold and not just the result of going too long between vacuums is if the smell gets stronger in one area of your house, or even one corner of a room. If you've washed the carpet, steamed the curtains, and taken out the trash without dislodging the strange reek, it could be mold.

 YOU USE A HUMIDIFIERThat moist air might be doing wonders for your skin, but it also could be encouraging the growth of mold.

Using a humidifier on a low setting during the dry winter or summer months shouldn't cause you much of a problem, but if you're constantly humidifying, you should regularly check to make sure all that extra moisture isn't feeding any mold. 

YOUR SINK OR TOILET FLOODED. Any occurrence of flooding pretty much guarantees that mold is on its way. Most people know that a large basement flood can lead to mold, but even a smaller incident like an overflowing bathtub or constantly leaking sink pipes can create conditions ripe for a mold infestation.

If you suspect your home is infested with mold, the best thing you can do is seek out the advice of a professional mold remediation specialist. They'll be able to test your home and any samples to determine the species of mold and potential hazard to you and your family. 

If you think you may have mold, contact us for a free, no obligation appointment. We offer mold testing, moisture readings, as well as complete mold remediation by our certified technicians. Email us at, call at 919.800.9435. or here through our website.


Bio-One Raleigh is owned by Karen & Rick Jacobs. We offer trauma, mold and hoarding cleanup services including biohazard, blood cleanup, suicide/homicide, feces & bodily fluid, animal waste, undiscovered death, and mold testing & remediation.

We proudly serve North Carolina’s Triangle & Triad areas including Raleigh, Durham, Chapel Hill, Cary, Apex, Pittsboro, Holly Springs, Clayton, Carrboro, Fuquay-Varina, Garner, Hillsborough, Mebane, Morrisville, Wake Forest, and Wendell; as well as the following counties; Wake County, Durham County, Cumberland County, Guilford County, Orange County, Chatham County, Harnett County, Johnston County, Nash County, Franklin County and Pill County. We also provide services to Greensboro and other areas throughout North Carolina/


Bio-One Inc. is the world's first crime scene cleaning franchise. Nationally respected and locally owned, Bio-One has earned its reputation through being trusted to handle the Mandalay Bay mass shooting in Las Vegas in 2017, the Pulse nightclub shooting in Florida in 2016, and consulted on the Sandy Hook Elementary School massacre in 2012. In 2019, Bio-One was once again included in the best and most comprehensive franchise ranking list – Entrepreneur magazine.