Mold typically grows in dark, damp places. It can damage your home and cause health problems, so it’s not just a cosmetic issue.

There are many types of mold that can be found in your home, each with the potential to cause health problems. Some types of mold are more dangerous than others, so it is important to know how to get rid of mold and which type is the most harmful.

What is mold?

It reproduces by releasing spores, which are like tiny seeds. Mold is a type of fungi that can grow both indoors and outdoors. It reproduces by releasing spores, which are small, seed-like particles.

Molds are beneficial to the ecosystem when they are growing outside, but can cause allergies and infections in some people when they grow inside.

Types of mold

There are several types of mold that can develop in any one area. You cannot always tell which type of mold it is without conducting a test. It is not necessary to identify the type of mold in order to remove it.

The most common indoor molds are:

• Cladosporium. This mold is brown, green, or black. Cladosporium grows in both warm and cool locations. It’s most often found on wood, carpets, or fabrics, and in heating and cooling ducts.
• Penicillium. This fuzzy mold is blue, green, or yellow. It’s often found under carpets, in basements, and in insulation, especially when there’s been water damage.
• Aspergillus. Aspergillus is green, white, or gray with dark spots and a powdery look. This type of mold doesn’t need much ventilation. It thrives in fabrics, walls, attics, and basements, as well as on dry food items.

There are other molds that aren’t found indoors as often as those listed above, but you may still find them in your home. These include:

• Alternaria. This fuzzy mold is white with black spots. It tends to grow in fabrics and wallpaper, near windows and air conditioners, and in bathrooms and kitchens.
• Aureobasidium. This mold is pink with black spots. It’s most commonly found on wood, walls, caulking, and grout.
• Stachybotrys chartarum. Also called black mold, this greenish-black mold grows on things with a high cellulose content. It’s usually found on paper, fiberboard, and gypsum board (drywall).
• Trichoderma. This mold is creamy white but turns green when it releases spores. It’s often found on wood, windows, and in bathrooms and kitchens.

Why does mold form in homes?

A home is often the ideal environment for mold to grow due to factors such as darkness, moisture, and a consistent temperature. Basements and other areas that may have these conditions are especially susceptible to mold growth.

Mold spores are in the air all the time, and if they find an area where they can reproduce, they will cause a visible mold problem.

Symptoms of mold exposure

Mold in your home can cause health problems, but not necessarily make you sick.

Touching or inhaling mold spores can cause allergy-like symptoms such as:

• runny nose and congestion
• eye irritation
• sneezing
• coughing
• sore throat
• skin rash
• headache
• lung irritation
• wheezing

You don’t need to go to the doctor right away if you’re exposed to mold, unless you have a medical condition that makes you more vulnerable to complications. If you think you might have an infection from mold exposure, though, it’s a good idea to let your doctor know.

Mold in house

They may be found indoors or outdoors. Mold can come in lots of different colors, like black, white, or spotted. It might look powdery, cottony, or velvety. You can find it both outdoors and indoors.

If you notice a spot and aren’t sure if it’s just an old stain or a splotch of dirt, here’s how to tell if it could be a sign of a mold problem:

• It has a musty, earthy smell.
• There’s a nearby source of moisture, but not much light.
• You see warping, cracking, or peeling of whatever material it’s growing on.
• A drop of bleach lightens its color in a minute or two.
• Unchecked mold will continue to grow. Dirt and old stains won’t.

How common is mold in buildings?

Mold was found in every single public building studied in 2017, with each one containing an average of 14 mold instances.

A 2012 study of 31 European countries found that mold was present in one in every six homes. The author noted that there can be a great difference in the prevalence of mold depending on the climate of the region.

How does mold get indoors?

Outdoor molds release tiny spores that float through the air. These spores can enter your home via:

• doors
• windows
• heating and air conditioning vents
• clothing and shoes
• pets

If mold spores are able to enter a building, they will grow if the conditions are right.

Mold spores grow in spaces with moisture, such as:

• in sinks, bathtubs, and showers
• near leaky pipes
• around windows
• in basements, crawl spaces, and attics

They can latch onto a variety of materials, including:

• fabrics
• carpet
• paper
• wood
• ceiling tiles
• dust
• paint
• wallpaper
• insulation

How do you know if you have a mold problem?

Hearing or seeing mold in your home is always a cause for concern as it can lead to health problems. Ideally, you should removed all mold from your home to avoid any issues.

One way to tell if you have mold is if you have a musty smell. Mold starts out as a little spot, but it can grow quickly. Unless it’s in an out-of-the-way location, you’ll likely notice it early on. One way to tell if you have mold is if your home has a musty smell.

Causes

Mold can be found everywhere and everyone breathes in mold spores. A mold allergy occurs when your immune system overreacts to certain types of mold, which your body sees as an allergen. This can cause symptoms, such as sneezing and nasal congestion.

Not all molds cause allergy symptoms. The most common types of molds causing allergy symptoms are:

• Alternaria
• Aspergillus
• Cladosporium
• Penicillium

Risk factors

You may be more likely to develop a mold allergy or experience mold allergy symptoms if you:

• have a family history of allergies
• work or live in a building that has greater than 50 percent humidity or poor ventilation
• work or live in an environment that’s been flooded, has leaky pipes, or is otherwise exposed to extreme moisture
• work in a job where you’re more likely to be exposed to mold, such as:
• farmworkers
• lumber millers
• woodworkers
• winemakers

Treatment 

If you are experiencing any symptoms that you think may be caused by exposure to mold, it is important to consult with a medical professional. It can sometimes be difficult to determine whether mold, another condition, or an allergy is the root cause of these symptoms. Your doctor may recommend skin or blood tests to help confirm whether or not you have an allergy to mold.

Treatments and preventative steps for mold allergies may include:

• medications, including nasal corticosteroid sprays and antihistamines
• allergy shots, which may be especially appropriate if you experience severe symptoms year-round
• managing humidity at home, including:
• maintaining the humidity below 50 percent with a dehumidifier
• regularly cleaning damp areas, such as basements and bathrooms
• keeping humid areas well ventilated
• quickly repairing any leaks

What helps with mold-induced nasal and sinus symptoms?

Some types of over-the-counter (OTC) medications may help relieve mild to moderate symptoms linked to mold exposure. These medications include:

• nasal sprays with corticosteroids
• antihistamines
• decongestants
• nasal rinse

If your symptoms are severe, you should see a doctor.

Complications and related mold illnesses

An allergic reaction or allergy-like symptoms are the most common reaction to mold exposure, but some people with certain risk factors may experience more serious health issues.

Infections

Although it is common to inhale mold spores without experiencing any health issues, people with some health conditions may be at risk of infection if they inhale certain types of mold.

Examples of mold-related infections include:

• aspergillosis
• histoplasmosis
• sporotrichosis
• valley fever (coccidioidomycosis)

You may be at a higher risk of these illnesses if you have conditions such as:

• asthma
• chronic obstructive pulmonary disease (COPD)
• sarcoidosis
• A compromised immune system, including people who take corticosteroids or have HIV
• cystic fibrosis
• tuberculosis

Asthma

Mold allergies can trigger asthma attacks in people who have asthma. People with mold allergies may need to use inhalers to manage their symptoms.

Some researchers have also found that children who are exposed to high levels of mold in their homes are at a greater risk for developing asthma.

Pneumonitis

An exposure to a large quantity of mold can, in some cases, lead to a more serious reaction called hypersensitivity pneumonitis. This type of exposure is most often the result of occupational or workplace hazards, rather than exposure to mold in your home.

Other complications

Although some people believe that black mold exposure can cause health problems like memory loss and headaches, experts say that there is no evidence to support this. Black mold spores can release toxic compounds called mycotoxins, but it’s not clear if these are harmful to humans.

Although some people believe that black mold exposure can cause health problems, there is no scientific proof to back up this claim. A study conducted in 2019 found that mycotoxins in the air are not linked to any diseases.

Tips for mold prevention

If you’re wondering how to prevent mold from taking over your home, here are a few tips that may help you stop it before it starts.

• Keep things clean – Dirty surfaces can provide mold with the organic food materials they need to take hold, and start growing throughout your home. Be particularly careful in areas that may be damp, such as kitchens, bathrooms, and attics.
• Address dampness – Dampness may be an issue if you live in an area that receives a lot of rain, or if your basement floods. Make sure to ventilate your home as much as possible in humid climates, and soak up any visible moisture as soon as possible.
• Keep the air dry – Air conditioners and dehumidifiers can help reduce the moisture content of the air. Keep your air at 40-50% relative humidity for the best comfort, and to prevent the growth of mold.
• Heat damp areas to dry them out – You may consider using space heaters or even a hair dryer to heat damp areas of your home where mold may form. This is a short-term fix, though. It’s best to address the source of the dampness, not the dampness itself.
• Keep the air circulating – Proper ventilation from attics, bathrooms, kitchens, laundry rooms, basements and any other place where moisture is common is essential. Make sure that your home is properly insulated and ventilated so that air can circulate properly.

How to tell if you have mold in your house

If you think you might have a mold problem in your house, look for these signs: Water damage: Water damage is one of the biggest causes of mold, so if your house has had any kind of water damage, you could have mold. Check for any water stains or discoloration on your walls, ceilings, and floors. Musty smells: If you’ve noticed a musty smell in your house, it could be a sign of mold. If you see any of these signs in your house, you could have a mold problem and you should call a mold remediation specialist. Mold can be hard to spot in a house as it can hide in walls, ventilation ducts, crawl spaces, and other difficult to see places. If you notice any water damage, such as water stains or discoloration on walls, ceilings, or floors, it could be a sign of mold. Another sign of mold is a musty smell in the house. If you think you might have a mold problem, you should call a mold remediation specialist.

If you smell a “musty” odor in an area of your home, this could be a sign that mold is present. Other symptoms of mold include a persistent runny nose, watery eyes, sneezing, and throat irritation.

Potential areas for mold growth are any places that have been exposed to a lot of moisture, like locations that have had water damage from flooding. Look for water where it’s not supposed to be, and check areas that have flooded in the past.

Using a mold exposure test

One way you can test for mold exposure on your own is by using a mold exposure test, which you can pick up at any home improvement or home supply store.

It’s easy, just follow the directions on the box. You’ll usually just need to brush the surface where you think mold might be present and then send the test strip or brush to a laboratory for analysis. If mold is present, they’ll let you know.

How to detect mold in walls

If you think there may be mold in your walls, there are a few ways you can test this.

If you want to check if there is mold behind your drywall, the easiest way to do it is to poke a hole in the drywall with a screwdriver and see if the area is soft. If it is, mold has probably rotted the surface away and you’ll be able to see it. Be careful when doing this – and don’t do it near any wiring or electrical outlets.

If you want to inspect the inside of a wall for mold, you could use a fiber optic camera. However, it may be better to hire a professional inspector, who has the tools required to thoroughly examine the wall and make sure it is free of mold.

Can I stay in my house with black mold?

We recommend against trying to remove black mold yourself if you have found a small, isolated patch. If you’re confident that there is no other mold present in your house, you may be able to stay and remove the mold.

If you see one patch of black mold, it is likely that there is more throughout your home. Simply removing the visible mold may not be enough.

If you’re not young or healthy, have a weak immune system, children, or pets, you should consider moving out of your house until the black mold has been treated.

Takeaway

Mold in your home doesn’t always cause health problems, but it should always be removed. If you have a mold allergy or a chronic lung condition such as asthma, you’re at a greater risk for more severe symptoms and complications.

There are a few things you can do around the house to make it harder for mold to grow. If you spot mold, take steps to clean it up yourself.