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.
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.
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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.
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.
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.
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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.
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The Department of Health does not recommend testing for mold. If you can visibly see mold or smell mold you may assume there is a mold problem. Air testing should never take place of a visual inspection as a visual inspection will help locate moisture issues that may contribute to mold growth. A visual survey and air testing may be recommended post remediation to verify a successful remediation project.Sometimes, mold growth is hidden and difficult to locate. In such cases, carefully conducted sampling may help determine the location of contamination. However, mold testing is rarely useful for trying to answer questions about health concerns. For more information, see MDH's "Testing for Mold " Fact Sheet
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To clean up and remove indoor mold growth, follow steps 1-6 as they apply to your home.
- 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.
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
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.
- Thoroughly scrub all contaminated surfaces using a stiff 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.
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 Department of Health, do not recommend the use of ozone to address mold or any other indoor air problems.
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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.