Health Effects That May Be Caused by Inhaling Mold or Mold Spores

Inhalation exposure to mold indoors can cause health effects in some people.

Molds may produce:

• Allergens
• Irritants
• Potentially toxic substances or chemicals (mycotoxins)

Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals. Mold does not have to be alive to cause an allergic reaction.

Allergic Reactions, Asthma Attacks, Irritant Effects

Allergic reactions to mold are common and can be immediate or delayed. Exposure to mold, mold spores, or mold fragments may cause non-sensitive individuals to become sensitive to mold, and repeated exposure has the potential to increase sensitivity. Allergic responses include hay fever-like symptoms such as:

• Headache
• Sneezing
• Runny nose
• Red eyes
• Skin rash (dermatitis)

Molds can cause asthma attacks in people with asthma who are allergic to mold. In addition, whether or not individuals are allergic to mold, molds can irritate:

• Eyes
• Skin
• Nose
• Throat
• Lungs

Other Health Effects

Breathing in mold may also cause hypersensitivity pneumonitis, an uncommon disease that resembles bacterial pneumonia. In addition, mold exposure may result in opportunistic infections in persons whose immune systems are weakened or suppressed.

When mold grows indoors, the occupants of a building may begin to report odors and a variety of symptoms including:

• Headaches
• Difficulty breathing
• Skin irritation
• Allergic reactions
• Aggravated asthma symptoms

These and other symptoms may be associated with exposure to mold. But all of these symptoms may be caused by other exposures or conditions unrelated to mold growth. Therefore, it is important not to assume that whenever any of these symptoms occurs that mold is the cause.

For more detailed information on mold and its health effects, consult:

• A health professional
• Your state or local health department
• Resource List for Public and Private Organizations Dealing with Environmental Exposures

Damp Buildings

Although mold is frequently found in damp buildings, it is not the only potential contaminant — biological contaminants other than mold, and non-biological contaminants are often present and may also cause health effects. Damp buildings may attract rodents and other pests. Damp or wet building components and furnishings may release chemicals indoors.

Potential contaminants in damp or wet buildings include:

• Bacteria
• Dust mites
• Cockroaches and other pests
• Chemicals emitted by damp building materials and furnishings

For more information on damp buildings and health effects, see the 2004 Institute of Medicine Report, Damp Indoor Spaces and Health, published by The National Academies Press.

Mycotoxins and Health Effects

As molds grow, some (but not all) of them may produce potentially toxic byproducts called mycotoxins under some conditions. Some of these molds are commonly found in moisture-damaged buildings. More than 200 mycotoxins from common molds have been identified, and many more remain to be identified. The amount and types of mycotoxins produced by a particular mold depends on many environmental and genetic factors. No one can tell whether a mold is producing mycotoxins just by looking at it.

Some mycotoxins are known to affect people, but for many mycotoxins little health information is available. Research on mycotoxins is ongoing. Exposure to mycotoxins can occur from inhalation, ingestion and skin contact. It is prudent to avoid unnecessary inhalation exposure to mold.

For more information on mycotoxins, see the 2004 Institute of Medicine Report, Damp Indoor Spaces and Health, published by The National Academies Press in Washington, DC.