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Questions about mold in your home?

What is Mold?

Mold is a type of fungus that is present in our natural environment.  Mold spores, which are tiny microscopic ‘seeds’, can be found virtually everywhere, including in homes, and are a part of the general dust found in homes.  These spores can grow on building materials and furnishings if conditions are correct.  Excess moisture is the critical factor in any indoor mold problem.  Mold growth should not be tolerated in our homes.  Eventually, the moisture and mold will damage what it is growing on, which may include both the building materials and personal belongings.  The key to preventing mold growth is to prevent moisture problems.

What makes molds grow in my home?

Mold enters your home as tiny spores. The spores need moisture to begin growing, digesting and destroying. Molds can grow on almost any surface, including; wood, ceiling tiles, wallpaper, paints, carpet, sheet rock, and insulation. The mold grows best when there is lots of moisture from a leaky roof, high humidity, or flood. There is no way to get rid of all molds and mold spores from your home. But you can control mold growth by keeping your home dry. 

What does mold need to grow?

Mold only needs a few simple things to grow and multiply:

Of these, controlling excess moisture is the key to preventing and stopping indoor mold growth.

What are the health concerns?

Health effects from exposure to mold can vary greatly depending on the person and the amount of mold in their home. The type of health symptoms that may occur include coughing, wheezing, nasal and throat conditions.  People with asthma or allergies who are sensitive to mold may notice their asthma or allergy symptoms worsen. Individuals with severely weakened immune system who are exposed to moldy environments are at risk of developing serious fungal respiratory infections. MDH recommends that people consult a medical professional if they are concerned about the effects of a moldy environment on their health.

Are the risks greater for some people?

There is wide variability in how different people are affected by mold exposures. However, the long term presence of indoor mold growth may eventually become unhealthy for anyone. The following types of people may be affected more severely and sooner than others:

Those with special health concerns should consult a medical professional if they feel their health is affected by indoor mold.

What symptoms are commonly seen with mold exposure?

Molds produce health effects through inflammation, allergy, or infection. Allergic reactions (often referred to as hay fever) are most common following mold exposure. Typical symptoms that mold-exposed persons report (alone or in combination) include:

How much mold can make me sick?

It depends. For some people, a relatively small number of mold spores can trigger an asthma attack or lead to other health problems. For other persons, symptoms may occur only when exposure levels are much higher. Nonetheless, indoor mold growth is unsanitary and undesirable. Basically, if you can see or smell mold inside your home, take steps to identify and eliminate the excess moisture and to cleanup and remove the mold.

What type of doctor should I see concerning mold exposure?

You should first consult a family or general health care provider who will decide whether you need referral to a specialist. Such specialists might include an allergist who treats patients with mold allergies or an infectious disease physician who treats mold infections. If an infection is in the lungs, a pulmonary physician might be recommended. Patients who have been exposed to molds in t

Are some molds more hazardous than others?

Some types of mold can produce chemical compounds called mycotoxins although they do not always do so. In some circumstances, the toxins produced by indoor mold may cause health problems.  Many, if not most, molds can produce potentially harmful substances, whether it’s allergens, mycotoxins, or other compounds.  Hence, all indoor mold growth should be removed promptly, no matter what type(s) of mold is present or whether it can produce toxins.

I heard about "toxic molds" that grow in homes and other buildings. Should I be concerned about a serious health risk to me and my family?

The term "toxic mold" is not accurate. While certain molds are toxigenic, meaning they can produce toxins (specifically mycotoxins), the molds themselves are not toxic, or poisonous. Hazards presented by molds that may produce mycotoxins should be considered the same as other common molds which can grow in your house. There is always a little mold everywhere - in the air and on many surfaces. There are very few reports that toxigenic molds found inside homes can cause unique or rare health conditions such as pulmonary hemorrhage or memory loss. These case reports are rare, and a causal link between the presence of the toxigenic mold and these conditions has not been proven. A common-sense approach should be used for any mold contamination existing inside buildings and homes. The common health concerns from molds include hay fever-like allergic symptoms. Certain individuals with chronic respiratory disease (chronic obstructive pulmonary disorder, asthma) may experience difficulty breathing. Individuals with immune suppression may be at increased risk for infection from molds. If you or your family members have these conditions, a qualified medical clinician should be consulted for diagnosis and treatment. For the most part, one should take routine measures to prevent mold growth in the home.

Are there any circumstances where people should vacate a home or other building because of mold?

These decisions have to be made individually. If you believe you are ill because of exposure to mold in a building, you should consult your physician to determine the appropriate action to take.

Can cleaning up mold be hazardous to my health?

Yes. During the cleaning process, you may be exposed to mold, strong detergents, and disinfectants. Spore counts may be 10 to 1000 times higher than background levels when mold-contaminated materials are disturbed. Take steps to protect you and your family’s health during cleanup:

My landlord or builder will not take any responsibility for cleaning up the mold in my home. Where can I go for help?

If you feel your property owner, landlord, or builder has not been responsive to concerns you’ve expressed regarding mold exposure, you can contact your local board of health or housing authority. Applicable codes, insurance, inspection, legal, and similar issues about mold generally fall under state and local (not federal) jurisdiction. You could also review your lease or building contract and contact local or state government authorities, your insurance company, or an attorney to learn more about local codes and regulations and your legal rights. You can contact your county or state health department about mold issues in your area to learn about what mold assessment and remediation services they may offer. You can find information on your state’s Indoor Air Quality program.

I’m sure that mold in my workplace is making me sick.

If you believe you are ill because of exposure to mold in the building where you work, you should first consult your health care provider to determine the appropriate action to take to protect your health. Notify your employer and, if applicable, your union representative about your concern so that your employer can take action to clean up and prevent mold growth. To find out more about mold, remediation of mold, or workplace safety and health guidelines and regulations, you may also want to contact your local (city, county, or state) health department.

You should also read the U.S. Environmental Protection Agency (EPA) Guidelines, Mold Remediation in Schools and Commercial Buildings.

I am very concerned about mold in my children’s school and how it affects their health.

If you believe your children are ill because of exposure to mold in their school, first consult their health care provider to determine the appropriate medical action to take. Contact the school’s administration to express your concern and to ask that they remove the mold and prevent future mold growth. If needed, you could also contact the local school board.

Your local health department may also have information on mold, and you may want to get in touch with your state Indoor Air Quality office.

You can also read the U.S. Environmental Protection Agency (EPA) guidelines, Mold Remediation in Schools and Commercial Buildings.

 

Home Inspections and Investigations

How do I tell if I have a mold problem?

Investigate don't just test. The most practical way to find a mold problem is by using your eyes to look for mold growth and by using your nose to locate the source of a suspicious odor. If you see mold or if there is an earthy or musty smell, you should assume a mold problem exists. Other clues are signs of excess moisture or the worsening of allergy-like symptoms.

Should I test for mold?

The Minnesota Department of Health does not recommend testing for mold. Instead, they suggest that you should simply assume there is a problem whenever you see mold or smell mold odors. Testing should never take the place of visual inspection and it should never use up resources that are needed to correct moisture problems and remove visible growth.

However, often times, mold growth is hidden and difficult to locate. In such cases, carefully conducted sampling may help determine the location of contamination. While mold testing is rarely useful for trying to answer questions about health concerns, it can provide valuable information regarding the location of mold and the events that caused the growth.

Mold Clean-up and Removal  

To clean up and remove indoor mold growth, follow steps 1-6 as they apply to your home.

 
  1. Identify and Fix the Moisture Problem
  2. Begin Drying All Wet Materials
  3. Remove and Dispose of Mold Contaminated Materials
  4. Clean Surfaces
  5. Disinfect Surfaces - optional
  6. Remain on Mold Alert

Identify and Fix the Moisture Problem - the most important step in solving a mold problem is to identify and correct the moisture source(s) that allowed the growth in the first place. Common indoor moisture sources include:

    • Flooding
    • Condensation (caused by indoor humidity that is too high or surfaces that are too cold)
    • Roof and plumbing leaks
    • Firewood stored indoors
    • Humidifier use
    • Inadequate venting of kitchen and bath humidity
    • Improper venting of combustion appliances
    • Failure to vent clothes dryer exhaust outdoors (including electric dryers)
    • Clothes line drying indoors

To keep indoor surfaces as dry as possible, try to maintain the home's relative humidity between 20-40 percent in the Winter and less than 60 percent the rest of the year. You can purchase devices to measure relative humidity at some home supply stores. Ventilation, air circulation near cold surfaces, dehumidification, and efforts to minimize the production of moisture in the home are all very important in controlling high humidity that frequently causes mold growth in our cold climate.


Begin Drying All Wet Materials - as soon as possible after becoming wet. For severe moisture problems, use fans and dehumidifiers and move wet items away from walls and off floors. Check with equipment rental companies or restoration firms for additional equipment or contracting options.

 

Remove and Dispose of Mold Contaminated Materials - items which have absorbed moisture (porous materials) and which have mold growing on them need to be removed, bagged and thrown out. Such materials may include sheet rock, insulation, plaster, carpet/carpet pad, ceiling tiles, wood products (other than solid wood), and paper products. Likewise, any such porous materials that have contacted sewage should also be bagged and thrown away. Non-porous materials with surface mold growth may be saved if they are cleaned well and kept dry (see step 4).

    Take Steps to Protect Yourself - the amount of mold particles in air can increase greatly when mold is disturbed. Consider using protective equipment when handling or working around mold contaminated materials. The following equipment can help minimize exposure to mold:

    • Rubber gloves
    • Eye goggles
    • Outer clothing (long sleeves and long pants) that can be easily removed in the work area and laundered or discarded
    • At a minimum, you should use an N95 or a N100 type disposable respirator.  Where mold growth is very heavy or covers an extensive area or if you are sensitive to airborne contaminants, greater respiratory protection may be more appropriate.  More protective options include half-face negative-air respirators with a HEPA filter (i.e., N100, P100).     

    Take Steps to Protect Others - plan and perform all work to minimize the amount of dust generated. Where possible, consider the following actions to help minimize the spread of mold spores:

    • Enclose or contain all moldy materials in plastic (bags or sheets) before carrying through the home.
    • Hang plastic sheeting to separate the work area from the rest of the home.
    • Cover supply and return vents in the work area.
    • Place fans in windows of work area to pull contaminated air out of the work area and exhaust it to the outdoors.
    • Remove outer layer of work clothing in the work area and wash separately or bag.
    • Damp clean the entire work area to pick up settled mold spores in dust.

     

Clean Surfaces - surface mold growing on non-porous or semi-porous materials such as hard plastic, concrete, glass, metal, and solid wood can usually be cleaned. Cleaning to remove and capture all mold contamination, is very important because dead spores and mold particles may cause health problems if they are left in place.

    • Thoroughly scrub all contaminated surfaces using a still brush, hot water and a non-ammonia soap/ detergent or commercial cleaner.
    • Collect excess cleaning liquid with a wet/dry vacuum, mop or sponge
    • Rinse area with clean water and collect excess rinse water.

Disinfect Surfaces (if desired) - after cleaning has removed all visible mold and other soiling from contaminated surfaces, a disinfectant may be used to kill mold missed by the cleaning. In the case of sewage contamination, disinfection is strongly suggested--contact the Minnesota Department of Health for appropriate advice.

    • Mix 1/4 to 1/2 cup bleach per gallon of water and apply to surfaces where mold growth was visible before cleaning. Apply the solution with a sponge or by other methods that do not over saturate or flood the surface area.
    • Collect any run-off of bleach solution with a clean and filtered wet/dry vacuum, sponge or mop. However, do not rinse or wipe the bleach solution off the areas being treated -- allow it to dry on the surface.

Always handle bleach with caution. Never mix bleach with ammonia -- toxic chlorine gas may result. Bleach can irritate the eyes, nose, throat, and skin. Provide fresh air (for example, open a window or door). Protect skin and eyes from contact with bleach. Test solution on a small area before treatment, since bleach is very corrosive and may damage some materials.

 

Remain on MOLD ALERT - Continue looking for signs of moisture problems or return of mold growth. Be particularly alert to moisture in areas of past growth. If mold returns, repeat cleaning steps and consider using a stronger solution to disinfect the area again. Regrowth may signal that the material should be removed or that moisture is not yet controlled.

 

Can ozone air cleaners remove indoor mold?

Some air cleaners are designed to produce ozone which is a strong oxidizing agent and a known irritant of the lungs and respiratory system. Studies have shown that ozone, even at high concentrations, is not effective at killing airborne mold or surface mold contamination. Even if mold was killed by ozone, the health threats would not be reduced until mold contaminants are removed through cleaning. Health experts, including the Minnesota Department of Health, do not recommend the use of ozone to address mold or any other indoor air problems.

When can we rebuild?

Rebuilding and refurnishing must wait until all affected materials have dried completely. It may take several days or weeks for building materials to fully dry and return to prior moisture conditions. A moisture meter may help measure drying progress.

Links to Internet Resources  

 

Center for Disease Control and Prevention

Environmental Protection Agency (EPA)

Minnesota Department of Health

Minnesota Department of Commerce

North Dakota Extension Service

Wisconsin Department of Health Services

Iowa Department of Health

New York City Department of Health & Mental Hygiene

Occupational Safety & Health Administration (OSHA)

American Lung Association - Upper Midwest