Despite the commonly held belief that black mold exposure is a serious health concern, no convincing research suggests that exposure to this type of mold causes conditions such as cancer or lung disease.
Mold is a type of fungus. It is present almost everywhere, including the air. In general, normal amounts of mold in the environment do not pose a substantial health risk to healthy people with regular immune system function.
There is no single type of mold called "black mold" — many molds are black. When people use the term, they may be referring to a type called Stachybotrys chartarum (S. chartarum), also known as Stachybotrys atra.
There is no scientific evidence to suggest that exposure to S. chartarum is more dangerous than exposure to any other type of mold.
However, some people may be more sensitive to mold spores than others, and they may develop respiratory symptoms after inhaling even a small number of spores. In large quantities, mold spores can cause ill health in almost anyone.
Therefore, people should remove any mold growth in the home and take steps to prevent it from growing back.
In this article, we look at some facts and myths surrounding black mold exposure. We also describe ways to remove and prevent mold growth in the home.
There is a commonly held belief that black mold — sometimes called toxic mold — can cause severe health problems because it releases mycotoxins. Mycotoxins are toxic substances that a fungus produces.
Some research suggests that mycotoxins from S. chartarum have a link to serious health problems in people who live in contaminated buildings.
One such health concern is mycotoxicosis — mold poisoning. Others include:
To date, there is no proof that inhaling mold spores causes these symptoms.
Mold exposure can cause other symptoms, however. According to the Florida Department of Health, it can cause the following types of health problems:
Allergy and irritation
People with allergies may be more sensitive to mold than others. If they come into contact with mold, they may experience symptoms, such as:
Severe mold allergies cause more severe symptoms, including shortness of breath.
Mold exposure may also worsen asthma or lung problems in people with preexisting lung conditions.
A 2012 study found that infants and young children exposed to mold in the home had an increased risk of developing asthma by the age of 7. The research examined 289 homes and 36 types of mold.
However, S. chartarum was not among the three types of mold most strongly associated with asthma development.
Research published in 2004 by the Institute of Medicine (IOM) indicates that spending time in damp indoor spaces is related to respiratory symptoms, including those of asthma.
For most people with healthy immune systems, molds are not a problem.
Some people believe that black mold is particularly dangerous because it releases mycotoxins. However, the fact is that all molds are capable of producing mycotoxins. Just because mold is present does not mean that it is producing these toxins.
Most cases of mycotoxicosis result from eating moldy food, rather than from inhaling fungal spores in the home or outdoors. The evidence does not indicate that inhaling or touching mold can cause mycotoxicosis.
The Centers for Disease Control and Prevention (CDC) state that there are very few reports of unique or rare health conditions resulting from mold in the home.
It appears that many types of indoor mold — not just black mold — may cause health problems in some people, but not in everyone.
Long term exposure to mold in the home, however, may be unhealthy for anyone.
People who are most at risk of the symptoms of mold exposure are:
- infants and children
- older adults
- people with allergies or asthma
- people with weakened immune systems
The main health concerns seem to relate to allergies and irritation, which typically cause respiratory symptoms.
People with weakened immune systems may also have a risk of fungal infection.
A doctor may diagnose a mold allergy based on a person's symptoms and their medical and family histories. They may also perform tests, including:
- a skin prick test, to check for reactions to common allergens
- blood tests, to measure the immune system's response to mold and to check for allergies to specific types of mold
To diagnose a systemic fungal infection in someone with a weakened immune system, a doctor may take a blood sample. In some cases, further testing may be necessary.
Treatment for a mold allergy is similar to treatment for other types of inhaled allergies. Options include:
- avoiding the allergen whenever possible
- a nasal rinse, to flush mold spores out of the nose
- antihistamines, to stop a runny nose, sneezing, and itchiness
- decongestant nasal sprays, a short term remedy for congestion
- nasal corticosteroids, to reduce inflammation
- oral decongestants, to reduce congestion
For a long term solution, a doctor may recommend immunotherapy. This involves getting a series of allergy shots over a few years.
Immunotherapy can be highly effective, but it is only suitable for certain types of mold allergy.
Individuals should treat all molds the same when it comes to removing them from the home.
To do this:
- Remove visible mold growth from hard surfaces with a commercial mold removal product, hot soapy water, or a mixture of 1 cup of bleach per gallon of water.
- Remove and discard soft or porous materials — such as carpets, insulation, or wallboard — that show signs of mold.
- Contact a professional if there is extensive mold growth in the home or if allergic reactions occur when cleaning moldy surfaces.
Mold thrives in damp and humid environments.
The most effective way to prevent mold growth is to monitor the humidity level in the home. It should be no higher than 50% throughout the day.
Check the humidity level regularly, as it can change every few hours.
Use a dehumidifier if necessary, especially during humid months.
To prevent mold, a person can also take the following steps:
- Regularly inspect the building for signs of water damage and mold.
- Clean the bathroom regularly and tackle mold and mildew as soon as it appears.
- Use exhaust fans in the kitchen and bathroom or open windows to improve ventilation.
- Install an air conditioner with a high efficiency particulate air filter — better known as a HEPA filter — to remove mold spores from the air.
- Add mold inhibitors to paints to stop mold growth on walls and ceilings.
- Avoid using carpet in the kitchen, basement, or bathroom.
- Recycle old books and newspapers, as these can become moldy quickly if they get damp.
- Deal with any flooding promptly by drying out soft furnishings and cleaning wet items with commercial products.
- Dispose of flood-damaged carpets.
To prevent or reduce the symptoms of a mold allergy:
- Close the windows at night, as there are more airborne mold spores during the cool, damp nighttime hours.
- Wear a dust mask while gardening.
- Stay indoors after a rainstorm, in damp weather, and other times when the mold count is high.
Also, use proper safety equipment when cleaning up mold in an industrial setting or after a natural disaster.
Based on current research, black mold exposure is no more dangerous than any other type of mold exposure.
It is impossible to avoid exposure to mold — the spores are almost everywhere around us.
In high amounts or in people with allergies, exposure to any mold may cause allergy symptoms. In people with underlying health conditions, it may lead to more serious complications.
Regardless of the type of mold, it is important to remove it from the home for hygiene and health reasons.
Anyone with concerns about the effects of mold on their health should speak to a doctor.