Mold

Molds are microscopic organisms that play an important role in the breakdown of plant and animal matter. Outdoors, molds can be found in shady, damp areas, or places where leaves or other vegetation is decomposing. Indoor molds can grow on virtually any surface, as long as moisture, oxygen, and organic material are present. When molds are disturbed, they release tiny cells called spores into the surrounding air.

How do people get exposed to mold?

People are exposed to molds every day and everywhere, at home, at work, at school, both indoors and out. Molds are generally not harmful to healthy humans.

Inhalation is considered the primary way that people are exposed to mold. Mold spores and fragments can become airborne and get into the air we breathe. People may also be exposed to mold through the skin. Workers should be properly protected with safety equipment when remediating, or cleaning up mold after a disaster. In some cases, people may be exposed to mold through their diet.

What are the most common forms of mold?

According to the Centers for Disease Control and Prevention, the most common indoor molds are:

• Cladosporium
• Penicillium
• Aspergillus
• Alternaria
• Stachybotrys chartarum (also known as black mold)

What are some of the health effects associated with mold exposure?

Symptoms stemming from mold spore exposure may include:

• Nasal and sinus congestion
• Eye irritation
• Blurred vision
• Sore throat
• Chronic cough
• Skin rash

After contact with certain molds, individuals with chronic respiratory disease may have difficulty breathing, and people who are immunocompromised may be at increased risk for lung infection. A study conducted by NIEHS-funded scientists shows that mold exposure during the first year of life may increase the risk of childhood asthma.

What can I do to get rid of mold in my home?

According to the U.S. Department of Housing and Urban Development (HUD), residents can do any of the following to prevent, and or get rid of, mold in their homes:

• Keep your house clean and dry.
• Fix water problems, such as roof leaks, wet basements, and leaking pipes or faucets.
• Make sure your home is well ventilated, and always use ventilation fans in bathrooms and kitchens.
• If possible, keep humidity in your house below 50 percent, by using an air conditioner or dehumidifier.
• Avoid using carpeting in areas of the home that may become wet, such as kitchens, bathrooms, and basements.
• Dry floor mats regularly.

After Hurricane Sandy in 2012, NIEHS made several resources on mold treatment and cleanup available.

More information, including a fact sheet, "Healthy Home Issues: Mold," is available on the HUD website.

Mold Remediation Training Tools

In English:

• Mold Cleanup and Treatment Orientation
• Mold Cleanup and Treatment Orientation (ePub format) 

In Spanish:

• Orientación de la limpienza y el tratamiento de moho 

Additional mold studies sponsored by NIEHS

• Guidelines for the Protection and Training of Workers Engaged In Maintenance and Remediation Work Associated with Mold
• Study Identifies Role of Mold in Asthma Development