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Health Department
Health and Community Services
43525 Elizabeth Road, Mount Clemens, MI 48043
(586) 469-5235

Mold In Your Home

What are molds?

Molds are microscopic fungi that live on plant or animal matter. They serve an important, positive role by helping to decompose organic matter. It is estimated that there are more than 100,000 species of mold. At least 1,000 species are common in the U.S.

Where are molds found?

Molds are found in virtually every environment and can be detected year round both indoors and outdoors. Mold growth is encouraged by warm and humid conditions. They can be found outdoors in shady, damp areas or places of decomposing vegetation. Indoors, mold can be found where there is sufficient moisture or where humidity levels are high, such as basements or showers.

What are the potential health effects of mold?

The most common types of mold are generally not hazardous to healthy individuals. People who have asthma, hay fever or other allergies or who have weakened immune systems are more likely to react to mold. Common symptoms include runny nose, eye irritations, skin rash, cough, congestion and aggravation of asthma or allergies. These symptoms should stop when mold level is reduced.

How do you know if you have a mold problem? Should the house be tested for mold?

Trained professionals can test for mold. However, these tests can be expensive and are usually considered unnecessary. Testing results will always be positive, since mold occurs everywhere. Additionally, there are no standards for safe or unsafe levels of mold. Whenever you see or smell mold, assume there is a problem and take measures to reduce the presence of mold in your home or building.

Large mold infestations can usually be seen or smelled.

What Is Stachybotrys chartarum (pronounced Stack-ee-BOT-ris; also known as Stachybotrys atra)?

This is the "black mold" that you hear and read about. Stachybotrys chartarum (SC) is one mold that is associated with health effects in people. SC is a greenish-black mold that can grow on materials with a high cellulose content (drywall, dropped ceiling tiles, wood) that are chronically moist or water damaged as a result of high humidity, water leaks, condensation or flooding. SC is a relatively uncommon mold. SC spores do not become easily airborne and therefore contamination of indoor air by SC is unusual.

How can you tell if Stachybotrys chartarum is present in your home?

Many molds are black in appearance but are not Stachybotrys chartarum. For example, the black mold commonly found between bathroom tiles is not SC. Stachybotrys chartarum can only be positively identified through microscopic examination or by specially trained professionals.

What should you do if you have mold in your home?

Indoor mold growth indicates a problem with water or moisture. You should not need to take any different precautions with Stachybotrys chartarum than with other molds.

Nonporous (e.g., metals, glass, and hard plas­tics) and semiporous (e.g., wood and concrete) materials contaminated with mold that are still structurally sound can often be cleaned with bleach-and-water solu­tions (1-2 c. bleach/gallon of water).

It is recommended that porous mate­rials (e.g., ceiling tiles, wallboards, carpeting and fabrics) that cannot be cleaned be removed and discarded. In rare cases with extensive mold growth (large surface areas greater than 100 square feet or where the material is severely degraded), clean-up may require extreme precautions.

How can you keep mold out of your home?

There is no practical way to eliminate all molds and mold spores in the indoor environment; the way to control indoor mold growth is to control moisture.

Common intervention methods for addressing mold problems include the following:

  • fixing water leakage problems
  • increasing ventilation in kitchens and bathrooms by using exhaust fans
  • maintaining heating, ventilating, and air conditioning (HVAC) systems
  • changing HVAC filters frequently, as recommended by manufacturer
  • keeping gutters and downspouts in working order and ensuring that they drain water away from the foundation
  • routinely checking, cleaning, and drying drip pans in air conditioners, refrigerators, and dehumidifiers
  • increasing ventilation (e.g., using exhaust fans or open windows to remove humidity when cooking, showering, or using the dishwasher)
  • venting clothes dryers to the outside
  • maintaining an ideal relative humidity level in the home of 40% to 60% by using a dehumidifier
  • locating and removing sources of moisture (controlling dampness and humidity and repairing water leakage problems)
  • cleaning or removing mold-contaminated materials
  • sloping surrounding soil away from building foundations
  • heating all rooms in the winter and adding heating to outside wall closets
  • reducing the number of indoor plants
  • using air conditioning at times of high outdoor humidity
  • removing materials with severe mold growth
  • using high-efficiency air filters.
  • using a sump pump in basements prone to flooding
  • vapor barriers, sump pumps, and aboveground vents can also be installed in crawlspaces to prevent moisture problems. 
  • Clean and dry damp/wet building materials and furnishings within 24 - 48 hours to prevent mold growth.
  • Prevent condensation: Reduce the potential for condensation on cold surfaces (windows, piping, exterior walls, roof or floors) by adding insulation.
  • In areas where there is a perpetual moisture problem, do not install carpeting


If you have any questions, call us at 586-469-5236, Monday-Friday, 8:30 a.m. - 5:00 p.m. or E-mail us now.

Other Resources

Interactive Mold House Tour