The 10 Most Dangerous Types of Mold to Your Health

If you live in a high-humidity state like Florida, no doubt you will have to contend with different types of mold at one time or another.

This is what leads us to ask: which mold is the most dangerous to your health? Most definitely, black toxic mold is the most dangerous. Exposure to it can cause symptoms of black mold exposure in children, adults, as well as pets. The other types of mold may be mild in nature, but you still don’t want to have them at home.

Mold grows when you have high humidity inside and outside. Therefore, it is best to stay informed about the different types of mold infestations that you might have at home.

Here, we shall look at these molds, but before then, you need to know the mold growth chart in relation to humidity. That way, you can know how to keep your eyes on your indoor humidity levels all the time.

1. Stachybotrys Chartarum (Black Mold)

Stachybotrys Chartarum

This fungus thrives in damp and humid environments, and you will know it by its black or dark green. Mostly, the black mold grows on materials with high cellulose content, such as wood, paper, and drywall.

This type of mold is notorious for causing different types of health problems. This mold causes sinusitis. As it matures, it releases mycotoxins that are harmful when inhaled or when they come into contact with the skin.

According to the World Health Organization, it is estimated that indoor dampness and mold are responsible for approximately 21% of current asthma cases in the United States.

That is not all, because a study published in the Environmental Health Perspectives journal suggests a significant association between mold exposure and the development of respiratory conditions.

Exposure to black mold can lead to a range of health issues, which have been well elaborated by the Centers for Disease Control and Prevention (CDC). Some of the symptoms of mold exposure include

  • Respiratory problems
  • Nasal congestion
  • Throat irritation
  • Coughing
  • Skin irritation

People who have compromised immune systems or pre-existing respiratory conditions are particularly vulnerable to exposure to black mold.

Prolonged exposure can contribute to more severe health issues, so get rid of black mold as soon as possible.

2. Aspergillus – brownish mold


This genus of mold comprises various species commonly found in the environment, mostly in decaying vegetation, soil, and organic matter. You will recognize this mold by its brownish color, but with maturity, it can start turning dark-ish.

While most forms of Aspergillus are harmless, some species can pose health risks, especially to individuals with weak immune systems.

Exposure to this type of mold can cause:


This is a group of diseases caused by inhaling the spores of Aspergillus. People with compromised immune systems, respiratory conditions, or underlying health issues are more susceptible to this mold. Aspergillosis can show itself as

  • Invasive lung infections
  • Sinusitis
  • Skin infection

Allergic Reactions

Being exposed to Aspergillus spores can trigger allergic reactions in some individuals. The symptoms may include respiratory issues, coughing, wheezing, and skin irritation.

3. Penicillium – blue-green mold

Penicillium mold

This is one of the most revolutionary types of mold that has played quite a big role in the world of medicine. There are more than 300 identified types of Penicillum.

The most popular of them is Penicillium notatum, which changed medicine in the 20th century with the discovery of the antibiotic penicillin by Sir Alexander Fleming.

Penicillum grows both indoors and outdoors. You shall recognize it by its blue or green color. Mostly, the mold grows on decaying matter, such as food materials. It is easy to identify it in the kitchen and in the bathroom, which are high-humidity places. This is why you need the best dehumidifier for the bathroom.

Exposure to this mold type will lead to allergic reactions, but there are no serious mold exposure symptoms.

4. Cladosporium – an allergenic mold


This type of mold genus is such a large family, as it has over 700 different species. It thrives both outdoors and indoors, in different types of environments. Thus, you are most likely going to find it in homes, offices, and natural settings.

Cladosporium mold is dark green, but it can also come with black spots on surfaces, and its spores are easily airborne.

In the outdoors, Cladosporium mostly grows on decaying plants, soil, and other organic matter. In the indoors, this mold can develop on damp surfaces like walls, carpets, and window sills. It will grow in areas with high humidity levels.

Symptoms for Cladosporium exposure

These are primarily allergic reactions, according to the American Academy of Allergy, Asthma & Immunology (AAAAI). These include:

  • Sneezing
  • Runny or stuffy nose
  • Itchy or watery eyes
  • Skin rashes

The severity of these symptoms can vary depending on a person’s immunity, and sensitivity.

To prevent Cladosporium mold growth, maintain proper indoor hygiene, fix water leaks, run a dehumidifier to lower humidity, and install proper ventilation.

5. Fusarium – bad mold for crops and humans


This genus of molds is found in soil and on plants, but it can also thrive indoors. If the conditions are right, this mold can produce mycotoxins, contributing to potential health risks.

It is notorious for causing Fusarium wilt in tomatoes, passion fruit, peas, and other plants. On the other hand, individuals exposed to Fusarium may experience respiratory issues, eye irritation, skin infections, and allergic reactions.

As usual, with mold, the first people to suffer are those with weak immune systems. Thus, to control its effects, lower the indoor humidity to prevent mold from growing.

This mold is brightly-colored or pale in color.

6. Mucor

Mucor mold

You shall identify this type of mold by its light gray or pale color, and its fast pace of growth. It will grow on organic matter in areas with high humidity. It is possible to find this kind of mold in the freezer.

This is not considered a toxic type of mold, but it can cause illness symptoms in people with respiratory issues, weak immune systems, and those who are sensitive and allergic to many things.

To prevent the growth of this mold, you need to control the humidity indoors. Using a dehumidifier in the kitchen, closet, and bathroom can help a lot.

Also, learn to inspect these places for signs of this mold type.

7. Aureobasidium


This type of mold is recognized by its dark brown to black color. This mold grows on various surfaces, including painted walls, window frames, and damp wood.

In the outdoors, it grows on plant debris and other organic matter. The mold is well-adapted to a wide range of conditions, and it can thrive in changing temperature levels.

While it is considered more allergenic than toxic, exposure to its spores can trigger allergic reactions in sensitive people. In return, this leads to symptoms such as:

  • Sneezing
  • Runny nose
  • Itchy eyes
  • Skin irritation

While it is not typically associated with severe health risks, prolonged exposure or high concentrations of Aureobasidium spores might make respiratory conditions worse in vulnerable people.

8. Trichoderma


This one is commonly found in soil, decaying wood, and other organic matter. Unlike some molds, Trichoderma is not an indoor type of mold such as you would find in a water-damaged basement or bathroom.

Instead, it is mostly recognized for its positive role in agriculture and industry. Certain species of Trichoderma are known for their ability to act as biopesticides, so they prevent pesticide attacks on the plants.

In terms of color, Trichoderma colonies can vary, but they are often white or green. The appearance of this mold depends on the specific species and the stage of growth. Trichoderma has rapid growth, and it produces fluffy, cotton-like mycelium.

Trichoderma is generally considered non-pathogenic to humans, and exposure to it is not known to cause significant health issues. In fact, some strains of Trichoderma are actively researched and used in biological control methods to combat plant pathogens.

The good thing is that Trichoderma does not cause health symptoms in humans. However, people with compromised immune systems or respiratory conditions may still experience reactions to fungal exposure.

Thus, it is very important to address any mold that grows in your home as soon as possible, including Trichoderma.

In fact, it would even be so much better to prevent the growth of the mold in the first place. Using a dehumidifier to prevent mold growth is important.

8. Chaetomium


If you have water damage at home, you are likely to find the Chaetomium mold growing in the basement. In the young stages of growth, this mold is grayish to white, but when it matures, it turns brown or dark green.

If left unattended, this type of mold can affect the structural integrity of a building, because it breaks down materials that contain cellulose.

This mold is not going to cause any illnesses, but exposure to it is not recommended. If you are recovering from another illness, it can cause you serious health issues.

What color mold is dangerous?

The danger of mold exposure does not come from the color of the mold. Rather, it comes from the type of the mold.

But since most black molds are toxic, well, it is fair to say that the most sinister ones are black. Therefore, if you see any black patches in your home, you should take care of it immediately. It is most likely black mold. Black mold causes respiratory issues in toddlers.

In toxicity levels, black mold is followed by dark-green mold. While no type of mold is good for anyone, look out for the fungi, and get rid of it as soon as possible.

At the same time, prevent the growth of mold. That is even better, by running a dehumidifier for basement. If you can keep the indoor humidity level below 55%, mold will not grow.

Also check my past articles on:

Pink mold in humidifier

Can vinegar help with mold

Does dehumidifier blow cold air?

Final thoughts

While black mold is the most dangerous, there are hundreds of other types, and you really don’t want them growing in your indoor environment. They produce dangerous mold spores that can start new colonies in your home.

You see, even the most harmless mold, that is, in regard to your health, will still cause harm to your carpets, walls, furniture, and other items.

If you live in Seattle with high humidity, run a dehumidifier always. All of the mold species we have discussed here thrive in humidity level higher than 55%. Thus, always keep your indoor humidity between 30 and 50%