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Mold in Your Home
Download a PDF of these frequently asked questions

Browse this information or download a print version (pdf)

What is mold?

Molds are fungi that grow in different shapes, sizes and colors. In nature molds break down dead and decaying material. In indoor environments, molds can cause structural damage because they consume and destroy the material they settle upon.

What causes mold to grow?

Molds need moisture to grow. Some household situations that lead to mold growth include:

1) Clogged gutters and downspouts,
2) Leaky plumbing,
3) Leaky roofs, and
4) Using hot water without venting the steam to outdoor air.

Also, when indoor air is warmer than outdoor air, moisture can collect on cold surfaces like singlepane windows, uninsulated walls, pipes and roofs.

Should I test for mold or have mold samples from my home tested?

Generally it is not helpful to test for mold in your home. There are no standards to judge "safe" levels of indoor mold. Therefore, testing cannot tell you if the amount of mold detected will harm your health. Typically if you can see mold or smell musty odors, you have a mold problem.

Can the government inspect my home for mold?

County and state public health departments do not have resources for inspecting private homes or testing for mold.

What should I do if I have moldy conditions in my home?
  • The key to mold control is moisture control. If mold is a problem in your home, clean up the mold and fix the water problem.
  • Keep indoor humidity at 30 to 60 percent.
  • Use air conditioners and/or dehumidifiers to reduce moisture in the air.
  • Use exhaust fans to pull indoor moisture (from cooking, dishwashing, showering and laundering) outside.
  • Inspect and repair your ventilation system.
  • Increase air circulation by moving furniture several inches away from the walls.
  • Remove carpeting in areas where there is ongoing moisture (from cooking, sinks, bathtubs and showers).

FAST FACTs: Household Mold

  • Install double-pane windows or insulation to keep moisture from collecting on cold surfaces.
  • Inspect and repair leaks in roofs, gutters, foundations and plumbing.
  • If you rent, consider taking pictures of moisture and mold problems and documenting the situation with your landlord.
  • Review Home Moisture Problems (pdf) by the Oregon State University Extension Service.
How do I get rid of mold?

After fixing a moisture problem, remove mold from hard surfaces by washing with soap and water and letting all washed surfaces dry completely. If you choose to use bleach, follow all label instructions, paying special attention to the precautionary statements and dilution rate. Remember, never mix chlorine bleach with ammonia-based cleaning products because they form a dangerous gas.

Absorbent materials such as clothing, moldy ceiling tiles and sheet rock may need to be replaced. The U.S. Environmental Protection Agency (EPA) recommends that experienced professionals clean mold problems larger than 10 square feet. Additional cleaning tips are provided in A Brief Guide to Mold, Moisture and Your Home by the U.S. EPA. If you rent, consider discussing clean-up options with your landlord and, if necessary, your rights as a tenant with the Community Alliance of Tenants.

What should I do if I think someone in my family is sick from mold?

If you think that you or anyone in your household is suffering from a mold-related illness, contact a health care provider. A doctor can determine if symptoms are allergy-related. Mold spores are common both indoors and outdoors. However, when spores are present in large enough numbers they can cause health effects such as: watery eyes, runny nose, sneezing, nasal congestion, itching, skin irritation, coughing, wheezing, difficulty breathing, headache and fatigue.

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