What is it?
Molds are fungi that can be found both indoors and outdoors.  Molds grow best in warm, damp, and humid conditions, and spread and reproduce by making spores. Mold spores can survive harsh environmental conditions, such as dry conditions, that do not support normal mold growth.

Where can mold be found?
Molds are found in virtually every environment and can be detected, indoors and outdoors, year round. Mold growth is encouraged by warm and humid conditions. Outdoors they can be found in shady, damp areas or places where leaves or other vegetation is decomposing. Indoors they can be found where humidity levels are high, such as basements or showers.
Possible Medical Problems Associated With Mold

  • Mild reactions to mold may include symptoms such as nasal stuffiness, eye irritation, wheezing, or skin irritation when exposed to molds.
  • Severe reactions may occur among workers exposed to large amounts of molds in occupational settings, such as farmers working around moldy hay. Severe reactions may include fever and shortness of breath.
  • Immunocompromised persons and persons with chronic lung diseases like COPD are at increased risk for opportunistic infections and may develop fungal infections in their lungs.

Recommendations for Decreasing Mold in Houses:

  • Keep the humidity level in the house between 40% and 60%.
  • Use an air conditioner or a dehumidifier during humid months.
  • Be sure the home has adequate ventilation, including exhaust fans.
  • Add mold inhibitors to paints before application.
  • Clean bathrooms with mold killing products.
  • Do not carpet bathrooms and basements.
  • Remove or replace previously soaked carpets and upholstery.

Tips for Cleaning Mold

In most cases mold can be removed from hard surfaces by a thorough cleaning with commercial products, soap and water, or a bleach solution of 1 cup of bleach in 1 gallon of water.
Absorbent or porous materials like ceiling tiles, drywall, and carpet may have to be thrown away if they become moldy.
Safety Tips when Using Bleach:

  • Never mix bleach with ammonia. Mixing bleach and ammonia can produce dangerous, toxic fumes.
  • Open windows and doors to provide fresh air.
  • Always follow the manufacturer’s instructions when using bleach or any other cleaning product.
  • If the area to be cleaned is more than 10 square feet, consult the U.S. Environmental Protection Agency (EPA) guide titled Mold Remediation in Schools and Commercial Buildings. This information can be applied to other types of buildings. You can get it free by calling the EPA Indoor Air Quality Information Clearinghouse at (800) 438-4318 or by going to the EPA web site at

Links for Further Information:

CDC:  Molds in the Environment
CDC:  Questions and Answers
EPA:  A Brief Guide to Mold, Moisture, and Your Home

Developed by:  Dana Gelb

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