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Healthy Homes - Mold


Mold basics

Molds can be found most anywhere – indoors and out. There are more than 100 different types of mold in Tennessee.  Many produce spores which are like seeds.  Spores can move easily through the air and can form new mold growth on surfaces when conditions are right.  Above all else, molds need moisture to live and grow.  Common molds found indoors include Cladosporium, Penicillium, Alternaria, Aspergillus and Trichoderma.  If there is mold growing in your home, there must be a source of water.  Get a quick glimpse of some of the most important ways to protect your home from mold by touring EPA's Mold House.

What are the health effects of mold?

Mold is usually not a problem indoors unless it finds a damp environment and starts to grow.  Molds can produce allergens, irritants, and in some cases, mycotoxins.  In our homes, allergic reactions and irritation are the most common health effects for people sensitive to mold.  Mold can trigger asthma attacks.  Many people will have no reaction to mold.  Some people , such as asthmatics, can have adverse reactions.

The term “toxic mold” is often used by the media or salespeople, but it is not accurate.  While some molds do produce toxins, the molds themselves are not toxic or poisonous.  These mycotoxins most often cause health problems only when eaten (moldy grains, peanuts or potatoes).  According to the Centers for Disease Control and Prevention (CDC), there is no proven link between mold and other health effects such as memory loss, lethargy and acute idiopathic pulmonary hemorrhage among infants.

With any health concern you may have, please consult with your family health provider.

How do I prevent mold from growing?

The key to mold prevention is moisture control.   Mold will not grow if moisture is not present.

Tips for mold prevention:

  • Keep your house dry
  • Fix leaky pipes, roofs, and windows
  • Maintain indoor humidity ideally between 30-50 percent.
  • Allow room air to flow behind furniture and in closets
  • Perform regular HVAC inspections and maintenance
  • Try not to carpet bathrooms or basements
  • Ventilate shower, laundry and cooking areas
  • Install French drains or sump pumps to control rain water
  • Promptly clean up and dry out your home after flooding

Tips to keep mold from coming back:

  • Prevent water, moisture and high humidity indoors
  • Discard porous items such as carpet, carpet pad, insulation or upholstery
  • Physically remove mold, do not just paint or caulk over moldy surfaces

How do I clean up mold?

When cleaning up more mold than what is typically found around a bathtub, wear personal protection such as gloves, mask and goggles.  Avoid touching mold or moldy items with bare hands.  Avoid breathing in mold or mold spores.  Do not let mold get in your eyes.

Dry non-moldy wet materials within 48 hours to prevent mold growth.  Discard or clean moldy materials.  Absorbent materials such as carpet, carpet pad, wallboard or insulation that hold water will often need to be discarded.  Mold can be removed from hard surfaces by scrubbing with water and detergent.  Dry the surfaces quickly and thoroughly.  If you choose to use bleach to clean up mold, mix one cup of bleach with one gallon of water.  Never mix bleach with ammonia.  Open windows and doors and turn on the exhaust fan in the bathroom to increase ventilation.

Simply painting or caulking over mold will not fix a moisture problem.  Materials that are not dry will mold again.  Removing damaged materials, fixing the water leak, and doing needed home repairs should end a mold problem.




Should I test my home for mold?

In general, it is not necessary to test for mold.  Whatever type of mold may be present should be cleaned.  The Centers for Disease Control and Prevention the Environmental Protection Agency do not recommend testing.  Since the effect of mold on people can vary greatly, the presence of mold in the home does not imply a health risk.

The Department of Health does not do mold testing.  We do not know of any agency that will test your home for mold.  If you can see or smell mold, it should be cleaned.  Look for a source of extra water.  Stop the moisture and thoroughly dry the area.  Home repairs may be needed to prevent future mold growth.

What about dampness?

Dampness is having too much water.  Whether the water is in the ground near the foundation or in the air as too much humidity, dampness can lead to mold growth.

Moisture meters and humidity monitors are available at many home and department stores.  Both can be helpful.  A moisture meter can tell you how much water is inside of building materials.  A moisture meter can tell if wallboard or flooring is damp inside.  A humidity monitor can tell you how much water is in the air.  A humidity monitor can show if the air in the room is too damp.  Damp building materials should be thoroughly dried.  If materials cannot be dried, they should be discarded and replaced.  Damp indoor air should be better circulated or dehumidified.  Bathroom exhaust fans, air conditioners, and dehumidifiers can help to control dampness.

Dampness around foundations, in basements or within crawlspaces may require extra care.  Foundations should have a vapor barrier in place.  Foundation or basement walls may need a water tight paint or sealant.  Basements and crawlspaces should have adequate ventilation and/or dehumidification.    Making sure rainwater does not flood up against the foundation wall is important.  A French drain or sump pump may be needed to remove groundwater.  Water near the foundation can move into the inside of the home making it damp as well. 

This webinar provides more information about addressing mold in your home.

Mold concerns when renting or buying a home?

If you have concerns about mold when buying or renting a home please click below for more information contained on one of our other Healthy Homes webpages:

For more information about mold, see our Environmental Health Topics section.


Additional resources

U.S. EPA:  A Brief Guide to Mold, Moisture, and Your Home
U.S. EPA:  Una Breve Guia para el Moho, la Humedad y su Hogar

U.S. EPA:  Mold Remediation in Schools and Commercial Buildings

U.S. EPA: Indoor Air Quality Tools for Schools kit

CDC National Center for Environmental Health:  Mold