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Common Types of Mold and How They Affect Your Health

Mold is a natural fungus that grows nearly anywhere as long as the conditions are right. Not all mold is hazardous, but the mold growth found in homes and buildings is concerning. Mold growth occurs when its spores have an organic food source, like cellulose found in common building materials, and a moisture source. This is why mold thrives in environments that are dark and damp including basements, bathrooms, crawlspaces, and more. It’s also why mold growth is commonly found in the aftermath of water damage. However, despite its natural occurrence, mold can be hazardous to your health.

Because of mold’s harmful nature, it’s important to know how to identify mold so that the problem can be addressed properly. There isn’t just one kind of mold. There are various types of mold, and some types are more harmful than others. With this variety, there are also different health effects and varying ways to treat the mold depending on the type.

The exact amount of mold types is unknown, because there are thousands upon thousands of them. However, there are certain mold species that are more commonly found in homes and buildings. These types of mold have their own characteristics and can be classified into three groups based on the harm they cause: allergenic, pathogenic, and toxigenic. Allergenic mold, as the name suggests, causes allergies. Pathogenic mold causes issues for people with an acute illness. Toxigenic mold can cause severely dangerous health problems that can be deadly. Additionally, toxigenic mold produces toxic substances.

Allergenic Molds


Alternaria is the most commonly found allergenic mold, and it often grows in response to water damage. It has a texture similar to velvet and has brown or dark green-colored hairs. This fungus can usually be found growing beneath leaky sinks, bathtubs, and showers. Alternaria can cause asthma-like symptoms in your nose, mouth, and upper respiratory tract.


Aureobasidium can be black, brown, or pink in color, but it usually becomes a darker brown with time. This fungus is often found on wooden surfaces, painted surfaces, and behind wallpaper. Exposure to aureobasidium can result in eye, skin, and nail infections and even skin rashes. That said, you shouldn’t directly touch this mold.


The color of chaetomium changes; it starts as white, turns gray, and then brown. Eventually, though, the fungus turns black. It has a musty odor and a cotton-like texture. You can find chaetomium growing in a damp basement or roof, near a leaking sink, and by other moist areas. Some of the health concerns it causes are skin and nail infections. It can also result in issues for people with weaker immune systems.


Penicillin has a velvety texture, is blue or green in appearance, and spreads fast. This fungus often develops along with water damage, growing on carpets, mattresses, wallpaper, and ducts. It can cause several respiratory issues, such as asthma and pulmonary inflammation. The longer one is exposed to penicillin, the greater chance there is for suffering from chronic sinusitis. It can also complicate health issues for people with immune disorders.


Trichoderma has five different subspecies, but usually, it appears white in color with patches of green and has a wool texture. The mold is often found growing on wet household surfaces like wallpaper and carpeting but also in HVAC ducts and air conditioning filters where condensation tends to build up. People may experience coughing and other nasal issues after exposure to this fungus.

Pathogenic Molds


Also an allergenic mold, aspergillus grows in thick layers of long spores that are shaped like flasks. The mold appears as long chains on surfaces and can be various colors, because there are more than 185 species of aspergillus. Among the health issues it causes are asthma attacks, respiratory inflammation, and lung infections.


Cladosporium is also an allergenic mold, and it can grow in both cold and warm temperatures. Its texture is similar to suede and has a brown or olive-green appearance. Cladosporium thrives indoors, so you may find it growing on carpets, fabric, upholstery, inside cabinets, and beneath floorboards.

This fungus may result in the following health problems: lung and skin irritation, asthma, sinus problems, lung infections, and skin rashes. Because of this, don’t directly touch cladosporium.


Mucor has a white or gray color and grows quickly in the form of thick patches. Because of the condensation that develops, mucor can be found by ducts and HVAC systems. It is also an allergenic mold, so it can lead to respiratory system issues like asthma and breathing problems. Mucor has also been known to cause fevers.

Extended exposure to this particular mold can lead to mucormycosis, which harms your lungs and sinuses and can even cause brain damage.

Toxigenic Molds


Acremonium changes appearance over time; it begins as a fine powder-like substance and is usually gray, orange, pink, or white. It often grows in cooling coils, drain pans, humidifiers, and window sealants because of the resulting condensation.

This mold can cause issues that affect your immune system, bone marrow, and other organs. Acremonium may also contain carcinogens, meaning it might cause impairment to your brain functions.


Fusarium is also an allergenic mold that can thrive in cold temperatures. It will spread throughout the property as well. This mold is a reddish pink color or white color that naturally grows on food and in compost. Fusarium can also develop as result of water damage, carpeting, wallpaper, other building materials and fabrics.

Allergy-wise, this fungus causes skin infections, sneezing, runny nose, sore throat, itchy eyes, and dermatitis. More exposure to fusarium can result in brain abscesses, bone infections, and other serious conditions. There can also be internal bleeding and hemorrhages from the mold’s toxins, which damage the nervous system.


Stachybotrys is also considered an allergenic and pathogenic mold that is also referred to as “black mold,” However, it can also be a dark green color and has a slimy texture. It grows on wood, paper, cardboard, and other cellulose material.

Stachybotrys is considered toxic because of the mycotoxins it can produce. These mycotoxins can cause depression, fatigue, breathing problems, sinusitis, persistent coughing, headaches, and a fever. This mold also can result in neurological problems for children.

Treating Mold Growth

When you come across mold growth on your property, use the aforementioned information as a guide to help you identify the fungus. With that knowledge, you’ll know what exactly you’re dealing with and how much of a problem it can be to your health and property.

Regardless of what type of mold it is, the best option is always to have a professional conduct mold removal. Some mold may only cause minimal harm, and others may cause severe health concerns. By taking yourself out of the situation, you can protect yourself from suffering any of its ill effects.

Meanwhile, professionals are properly equipped to conduct mold cleanup in a safe manner. They know how to properly identify and treat the mold without worsening the problem. In fact, if you try to clean mold yourself, you may end up creating an even bigger issue, causing the mold to spread and increasing your risk of negative health effects.

ServiceMaster Restoration by Complete can help homes and businesses in Staten Island, NY, and Brooklyn, NY, with effective mold remediation services. Our professionals have the proper knowledge, cleaning equipment, and cleaning products to thoroughly remove mold.