Signs Of Mold In Air Vents

ByMarc Silberberg


Mold is something that makes us all cringe when it appears in our home or commercial space. But what if it’s in the air of your living space and it just can’t be seen. Sometimes people may smell mustiness which can signal a mold problem but they still won’t be certain where it’s stemming from. Since every case is different one cannot say for sure where exactly the mold is coming from unless it’s been checked out by a mold inspection and testing specialist. With that said it’s not uncommon that the mold spores are being blown into the living space from the ducts and vents of your HVAC system.  

Ductwork can be the perfect breeding ground for mold and mildew which is why you should have your air ducts cleaned at least once every four years. It will give you the peace of mind knowing that there are no unwanted particles living there like dust, dirt, mold, and debris. At the same time your heating and cooling system will perform much better, allowing the proper disbursement of conditioned air. 

Below we will discuss some of the signs of mold in home air vents or ducts. It’s important to keep a close eye on the registrars located on the ceiling and walls. These will give you some insight into what might be going on in your air ducts. Sometimes it may be surface mold in the form of tiny black spots that can be treated with a non toxic fungicide spray while other times the discoloration on the vent may signal something more severe like actual mold growing in your air ducts.

Why Does Mold Grow In Air Ducts & On Vents?

Unfortunately, with the constant flow of cool air there can be a build up of condensation within the air ducts or on and around the registers. Sometimes it might be a small area of a steel air duct while other times it can be a whole entire flexible air duct connector that will need to be replaced. Depending on how badly contaminated it is will determine the work necessary to get rid of the mold issue.

In general, moisture is the breeding grounds for mold in any area of your home. This is why homeowners will have dehumidifiers running in a basement of crawl space to prevent the build-up of moisture that creates the perfect environment for mold to grow. If you do spot a moist area, make sure to take care of the issue right away to prevent mold from growing there. The hard part about mold in your air ducts is that you don’t see it and with everyone recovering from COVID-19 chances are they won’t smell it either. That’s why it’s important to keep a close eye on the air vent grills and registers that tell the story of what’s really going on inside your air ducts.

Treatment For Mold On Vents & Registers

Not always does mold on the outside of the vents mean that there is mold within the air ducts. Often the contamination is limited to the surface area of the vent which can be treated with a non toxic fungicide spray. Homeowners might think to make their own mold killing solution out of bleach or ammonia but most health experts do not recommend this due to the toxic aerosols that can be breathed in. Ridding the vents of mold can be accomplished by purchasing a non toxic fungicide spray approved by the Environmental Protection Agency or better known as the EPA. If your vent is so constricted that the spray is not doing a good enough job, you may just want to replace it.

Sometimes when the vent is removed you will have a pretty clean air duct. So what’s happening is that the moisture is getting trapped in between the supply vent and the ceiling that’s allowing the mold to breed. The good news is that the mold issue is not from your duct work but simply limited to the area around the vent. For this you will want to remove the vent, clean it well, and reposition it so that it fits snug into the duct. Other times the vent will be pointing directly onto the ceiling that allows for condensation to accumulate on a specific area on a constant basis that will breed mold. First make sure the mold is removed from the ceiling and then redirect the direction to which the slats are pointing. You want them pointing towards the living space, not the ceiling.

Other Common Areas In The Home Where Mold Accumulates 

Mold can grow under the fridge by the motor area, beneath the kitchen and bathroom sinks, and on the bathroom ceiling and walls. This is especially true when there is no window in the bathroom and the only ventilation is a vent fan. It’s important to make sure that the bathroom vent fans are working and exhaust the unwanted moisture from a steaming shower. Proper function of the fan should be a clear vent line and exhaust to outside of the home. Often contractors will just lead the vent to exhaust into the attic and can cause an unwanted moisture build up there which can lead to a bigger mold issue.

Mold In Carpeting 

If there is a spill on the carpet or continuous dampness, the moisture can get trapped and lead to a mold issue beneath the carpet. The only way to know if there is mold beneath the surface is simply to lift up the carpet and check. A more common problem occurs when there is a bed or heavy furniture where the basic home vacuum cleaner can’t get to. At the same time the person navigating the vacuum can’t move or get underneath to vacuum that area. Over the course of time there will be a build of dust that rests atop the carpet fibers. Besides for the dust being problematic to those who are sensitive to it, the dust will create a layer over the carpet fibers that creates a breeding ground for mold. The way to avoid this is to actually have someone move the bed or furniture which will allow you to vacuum it up. As the saying goes “An ounce of prevention is worth a pound of cure”.

Central Humidifiers & The Moisture Challenge

Regions in the United States of America that tend to be more humid will often have to deal with mold issues in their homes. Take for example the State of Florida, during the summer months the average dew point will be around 70 degrees with the relative humidity of over 90%. That’s a pretty big challenge for home owners when it comes to mold which is why there are so many mold cleaning specialists in Florida. On the other hand, states with dryer climates like Arizona will have to deal with issues like waking up parched. It is for that reason that HVAC installers will place a whole house humidifier into the air cooling system. The problem arises when too much moisture is being pumped into the duct work which can create a breeding ground for mold. Homeowners can get a hygrometer to keep a close eye on the home’s humidity percentage. According to the Mayo Clinic, your home’s humidity should be somewhere between 30% and 50%. Anything higher than 50% is extra humidity and can lead to a mold issue.

Symptoms Of A Mold Issue In Your Home

Most mold issues do not impact a person’s health since the amount of actual mold spores in the conditioned air space is very minimal. However, there are signs of a bigger contamination issue when a person is getting frequent headaches, excessive coughing, or feeling lethargic. Before doing anything you should visit a medical professional to rule out anything else. If the doctor feels that it may be linked to mold, he or she will do a blood test and check for elevated levels of aspergillus penicillium mold in the bloodstream. In regard to checking your home, a mold specialist will need to perform a set of tests to check the levels mold in the conditioned air space. If there indeed is mold present in your home it needs to be taken care of right away.

Who Does Mold Affect The Most?

Mold can affect anyone but more so those with compromised or weaker immune systems like infants and the elderly. Also people with allergies will generally be more sensitive to mold. According to the Centers for Disease Control and Prevention or better known as the CDC, aspergillus penicillium mold will have a greater impact on those with respiratory diseases like chronic obstructive pulmonary disorder, and asthma. It is they who will find it very difficult to breathe when being exposed to mold in their living space.

Final Words

It’s vital to keep mold out of your home but it’s even more important to make sure that it doesn’t get there in the first place. If you are seeing mold around the vents or registers these most likely can easily be cleaned with a toxic fungicide spray. If the air in your home smells of mildew you may want to get your ducts cleaned by a NADCA certified specialist. They will let you know what’s going on in your ductwork and get rid of surface elements like dust, dander, mites, and mold. If there is a more serious mold issue, call down a mold inspector who will do handful of test to identify where the mold is coming from. 

Just like with many things in life that appear to be bad there is always a good part of it too. In the case of mold, it was penicillin that continues as a treatment for many bacterial infections and has saved countless lives. 

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