Mold can invade your home and rapidly spread without you realizing it, ultimately putting your loved ones at risk. Mold issues may start in a lesser-used area with high temperatures and humidity such as a garage or attic, but the microscopic spores can spread throughout the air and begin reproducing in the walls of your home leading to a range of short and long-term health effects.
A lot of people have questions about what mold is, how to identify mold, the different types of household mold, and if air purifiers help with mold — so we’ve detailed everything you need to know in this comprehensive guide.
What is mold and how does it grow?
Mold is a type of fungus made up of microscopic organisms that grows in places that are warm, damp, and dark. In nature, mold acts as a decomposition agent and is crucial for the breakdown of dead organic matter such as plants. However, when mold is found indoors it can be dangerous to the area’s inhabitants.
Like all living things, mold needs water, food, and oxygen to live and grow. Areas with high humidity or exposure to water leaks are ideal for mold because they provide plenty of moisture. To get the nutrients it needs to grow, mold will feed off of the surface it grows on resulting in decay. Certain surfaces provide ideal growing conditions for mold such as paper and wood, but it can also grow on fabric, plastic, and glass surfaces as well. In fact, different types of mold thrive well on different surfaces. For example, cladosporium is a type that commonly grows on carpets, while alternaria is typically found in showers or bathtubs.
As mold grows, it releases reproductive spores that travel through the air. These spores are microscopic, meaning you won’t be able to see them without extreme magnification. As spores travel through the air, they will attach to objects such as clothing, or even other living beings such as pets. This is generally how mold enters a home, at which point it will move from location to location until it finds a spot with ideal growing conditions. Some spores will easily move and settle multiple times, while others will cling to surfaces and will only dislodge after direct contact with another surface.
The EPA notes that “Spores may remain able to grow for years after they are produced. In addition, whether or not the spores are alive, the allergens in and on them may remain allergenic for years.”
How to test for and identify mold
What does mold look like? You may have an idea, but the various types of mold can make this a lot more confusing than you’d think. In fact, a lot of people commonly mistake mold for dirt which can have serious health implications when left untreated. To help you identify mold, follow these steps to check and test for mold in your home.
1. Do a bleach swab test on concerning spots
If you see a spot and are concerned it’s mold, dip a cotton swab in diluted bleach and swipe on the area. If the area you touched with the bleach swab lightens after a minute or two — you may be dealing with one of the various types of mold. On the other hand, if the area remains dark — it’s likely just dirt.
2. Probe the area to see if it crumbles
If the area appears to be mold based on step one, you’ll want to determine if it’s just surface level damage or deeper. If the area seems sturdy and texturally the same it’s likely just a surface level mold that can be cleaned with a bleach solution. However, if the area feels soft or crumbles, it means the fungi have spread which creates rot as it feeds off nearby surfaces.
3. Check for leaks
You should check for nearby water leaks anytime you find mold in your home. Start by looking at pipes near the area with mold, but also check pipes in surrounding rooms — as water can travel in any direction once absorbed into material such as drywall. Fix any leaks you find, but if none are found you’ll want to start looking for wet spots on walls and ceilings. Check both indoors and outdoors for areas where water might be leaking in. Pay special attention to downspouts where water flows out near a wall, as this can cause rot over time. Also, check the area around indoor vents for signs of mold — as this could indicate an insulation problem with the air duct.
Once you’ve identified whether an area of concern is mold, how deep the mold goes, and have an idea where it’s coming from — the next step is to find out which type of mold you’re dealing with so you can understand what you’ve been exposed to and take the necessary steps to remove it from your home.
Different types of household mold
Have you ever wondered why mold on cheese is fine to eat, but mold inside a home is considered hazardous? There are several types of mold, some of which are more dangerous than others. In fact, there are thousands of types of mold which have a range of colors such as green, blue, white, or black among others.
Additionally, each type of mold falls under one or more classifications that reflect its potential danger to humans and pets:
- Allergenic Mold: This common type of mold causes allergies and may also result in structural damage to exposed homes.
- Pathogenic Mold: Pathogenic mold can cause infections (even for people in good health), and is especially dangerous for individuals with a compromised immune system from another illness or age factors.
- Toxigenic Mold: These molds produce and release toxic substances called “mycotoxins” which are a serious health risk when inhaled.
When it comes to protecting your home, here are the most common types of indoor mold to be aware of:
Acremonium is a toxigenic mold that starts out as a small moist spot, but transforms into a powdery substance that could be pink, grey, orange, or white. Acremonium grows in areas where condensation occurs, such as humidifiers, cooling coils, drain pans, or window sealants. Acremonium is also known to grow alongside other types of mold such as Stachbotrys (black mold) and other strains. Exposure to Acremonium is incredibly dangerous, as it has the potential to damage the immune system, internal organs, and bone marrow.
Alternaria is an allergenic mold and is one of the most common types of mold found outdoors and indoors. Outdoors, it’s typically found on soil or plants, but can make its way indoors on shoes or clothing. Once inside, the mold can spread and typically grows around showers or bathtubs. You can recognize Alternaria by it’s velvet-texture, comprised of dark green and brown hairs. While most molds only thrive in moist conditions, Alternaria is dangerous because it can grow just as easily in dry areas and it spreads incredibly fast. It’s most concerning for its potential to cause asthma attacks, but it can also cause allergy symptoms as well.
Aspergillus is another type of allergenic mold that thrives in a moist environment, and is known for being able to feed off a staggering variety of organic material for nutrients. It’s known to grow on leather and fabrics, but can also grow on food among other surfaces. You can recognize Aspergillus by it’s long, flask-shaped spores that come in a variety of colors. It may even appear to be multiple colors, such as black on the surface with a white or yellow undertone. When it comes to health effects, Aspergillus has been linked to allergic reactions and lung infections.
Chaetomium is a pathogenic and sometimes toxigenic mold that typically appears in water damaged areas. Chaetomium is characterized by a cotton-like texture, and it transforms from a white to grey and eventually black color over time. You’re most likely to see this type of mold near a leaking roof, sink, or basement and you may also notice it having a musty odor. Common symptoms of Chaetomium exposure include skin and nail infections, but the mycotoxins it produces can also lead to more concerning issues for individuals with weakened immune systems.
Cladosporium is an allergenic mold that also thrives in a moist environment, and is commonly found on carpets or wallpaper. It appears in clusters of black, yellow, or green spots that spread quickly if not quickly treated. In fact, Cladosporium can even spread under floorboards due to its ability to survive in both warm and cold conditions. Cladosporium typically causes allergies, but exposure also has the potential to cause respiratory issues such as lung infections that can be more severe which is why it should be removed immediately.
Fusarium is both an allergenic and toxigenic type of mold that tends to grow in areas that are cold and wet, often appearing indoors on carpets. You’ll typically find Fusarium growing on fabrics, but it can also grow quickly on food. The mold usually appears with a pink, white, or red color. People sensitive to molds may experience flu-like symptoms when exposed to Fusarium, while those with asthma may experience wheezing and coughing. The toxins produced by Fusarium also cause damage to the nervous system that can lead to internal bleeding after prolonged exposure.
Mucor is an allergenic mold that has a white or grey appearance and grows quickly in thick patches, usually near air conditioning systems, air ducts, or damp carpets. Mucor causes health issues in the respiratory system including asthma symptoms and difficulty breathing. Prolonged exposure to Mucor can also lead to the development of mucormycosis, which is a fungal infection that damages the sinuses, lungs, and brain. As a result of Mucor’s danger, it should only be treated by professionals with proper safety gear.
You may have misread this as Penicillin (the commonly used antibiotic), but Penicillin is actually derived from Penicillium mold. While Penicillium mold is used to make medicine, it is by no means healthy. In fact, Penicillium spores are associated with respiratory issues such as asthma and chronic sinusitis. You can recognize Penicillium mold by its blue or green color and velvet texture. It’s commonly found on surfaces with water damage such as carpets, wallpapers, and mattresses. Penicillium mold spores can also spread quickly from room to room, so make sure to check the entire house if you do find it.
Stachybotrys (Black Mold)
Often referred to as “black mold” or “toxic mold”, Stachybotrys is indeed a toxigenic mold that appears in black or dark green clumps and requires constant moisture to thrive. Stachybotrys has a dark green or black color with a slimy texture. In addition to it’s dark appearance, it has a notably musty smell. Constant moisture is essential for Stachobotrys to grow, so you’ll typically find it growing on materials such as wood or cardboard in areas with high humidity for several weeks.
Last but not least, is Trichoderma — a type of allergenic mold that grows on wet surfaces and moist areas such as wallpaper and carpet. Trichoderma is recognizable by its white color and green patches. While Trichoderma is generally non-pathogenic, some species of this type of mold do produce and release mycotoxins that can lead to health problems such as liver infections. Trichoderma also contains an enzyme that destroys wood and textile, making it extremely dangerous for the structural integrity of your home if it finds its way into walls.
Mildew vs Mold
When looking at a potential mold spot in your home, it’s important to determine if the area is mold or mildew. Both refer to fungi that thrive in warm areas with plenty of moisture, but there are physical differences in mold and mildew that can help you identify which one you’re dealing with. Tactics used to remove mildew will likely prove ineffective against mold, so make sure you know what you’re dealing with before taking action.
What is Mildew?
Much like mold, mildew is a fungus that can quickly grow on a plethora of surfaces such as fabric, paper, leather, and more. Mildew thrives in places that are warm and moist, and you can recognize it as gray or white fungal patches that appear on surfaces with these conditions. Because mildew thrives in wet conditions, it is most commonly found in bathrooms, kitchens, and basements where water is present and you can identify it by a strong musty odor.
As with mold, mildew travels via airborne spores and the inhalation of these spores may cause health issues such as coughing, headaches, or trouble breathing. Generally however, mildew is considered much less dangerous than mold.
What is the difference between mold and mildew?
Although mildew and mold share many similarities, there are a few key differences you should be aware of that can help you determine which one you’re dealing with and how to proceed with removal:
- Appearance: Mildew is easily identifiable by it’s white or gray color and strong musty odor that appears on the surface of affected areas, whereas mold comes in a range of colors and types. Mildew also grows in small patches as shown in the featured image above, and its texture is usually fluffy or powdery. By comparison, mold tends to be fuzzy or slimy and grows below the surface (or within) affected areas.
- Structural Damage: Mildew typically only grows on the surface of affected areas, meaning it’s much less damaging than mold which will grow well into wood or other materials resulting in crumbling and the loss of structural integrity.
- Health Effects: While both mildew and mold have negative health effects from exposure, mold is far more dangerous. Mildew spores may cause allergy-like symptoms such as coughing and difficulty breathing, whereas mold exposure has potentially fatal symptoms depending on the affected individual and type of mold they were exposed to.
Removal: Mildew is much easier to remove than mold, which typically requires professional assistance and specialized equipment to treat. Because mildew only grows on the surface and has only minor health effects, you can typically remove it with a commercial cleaner and scrubbing brush (just make sure to wear gloves and a face mask). By comparison, mold penetrates beneath surfaces at a microscopic level and is able to survive in extreme conditions, so you’ll likely need professional help to completely eradicate it.
Mold health risks
Mold sensitivity varies from person to person, so it’s possible you may not experience any symptoms while someone in the same household could simultaneously be dealing with severe issues.
The most common problematic symptoms from mold exposure are from allergic or asthmatic reactions, which may be immediately noticeable or develop from prolonged exposure. In addition to the mold growing on surfaces, the airborne spores can also contribute to problematic symptoms.
Mold allergy and asthmatic symptoms:
- A stuffy or runny nose
- Watery, red, or itchy eyes
- A sore throat
- Skin irritation or rashes
Although people who are allergic to mold are most likely to experience these symptoms, in some cases non-allergenic individuals may also experience issues. For people with asthma, mold can make breathing more difficult or even act as a trigger for asthma attacks. In severe cases, mold may even cause a fever or difficulty breathing.
Furthermore, in 2004 the Institute of Medicine published a landmark report entitled Damp Indoor Space and Health which linked mold exposure to “upper respiratory tract symptoms, cough, wheezing, and asthma symptoms in sensitized persons.”
Do air purifiers help with mold?
Air purifiers help capture mold spores from the air, preventing them from reproducing and spreading throughout your home. While air purifiers won’t help treat active mold that’s already present on surfaces, they are a great way to control the spread of airborne mold particles.
If you don’t have a mold problem but are concerned about it becoming an issue, an air purifier will help capture mold spores that enter your home before they have a chance to land on surfaces where they can grow and cause problems. If you are currently dealing with a mold issue in your home, you should use an air purifier in conjunction with traditional surface treatments to prevent mold spores from spreading to other areas.
What’s the best air purifier for mold?
The best air purifiers for mold are those that utilize True HEPA filters. HEPA stands for High Efficiency Particulate Air, and these filters are highly effective at capturing microscopic particles such as mold spores found in the air.
True HEPA filters are even more effective than regular HEPA filters, as True HEPA filters are subject to even stricter standards of efficiency. Typical HEPA filters are rated to capture 99.97% of particles larger than 0.3 microns. Alen’s True HEPA filters capture at least 99.99% of all particles 0.1 microns or greater in size, according to 3rd party lab testing. For reference, mold spores are usually between two and ten microns in size. This means True HEPA filters are an effective way to address airborne mold spores in your home.
One thing that’s important to consider when choosing an air purifier to control mold, is the size of the room you’ll be placing it. In order to effectively operate, you’ll need an air purifier that can circulate and clean all of the air in a room in a reasonable amount of time.
For large rooms and common areas, we recommend the Alen BreatheSmart 75i which cleans 1,300 square feet every 30 minutes. Perfect for the living room or master bedroom, this air purifier quietly operates to circulate air and capture mold spores.
If the room is a bit smaller such as a child’s bedroom or home office, we recommend the Alen BreatheSmart 45i which provides coverage for up to 800 square feet. Much like the BreatheSmart 75i, this purifier operates at a whisper-quiet noise level as it cleans the room’s air.
Have questions about which air purifier is right for you? Check out our in-depth buying guide or take our air purifier quiz to help find a purifier to meet the unique needs of your home.