Protect Yourself from Mold

After natural disasters such as hurricanes, tornadoes, and floods, excess moisture and standing water contribute to the growth of mold in homes and other buildings. When returning to a home that has been flooded, be aware that mold may be present and may be a health risk for your family.

Mold Information

Environmental Health does not provide mold testing, evaluate mold problems, or provide consulting services.

Molds are simple, microscopic organisms and are found virtually everywhere - indoors and outdoors. Molds can be found on plants, foods, dry leaves, and other organic material. Molds are needed for breaking down dead material. Mold spores are tiny and lightweight, and this allows them to travel through the air. Mold growths can often be seen in the form of discoloration, ranging from white to orange and from green to brown and black.

When molds are present in large quantities, they​ can cause allergic symptoms similar to those caused by plant pollen.

Mold Problem Resources

• California Department of Public Health
  • ​Mold
• US Environmental Protection Agency
  • Mold Resources
• Centers for Disease Control and Prevention
  • General Information about Mold
  • Facts About Stachybotrys chartarum
• American Industrial Hygiene Association
  • The Facts Abo​ut Mold

People at Greatest Risk from Mold

People with asthma, allergies, or other breathing conditions may be more sensitive to mold. People with immune suppression (such as people with HIV infection, cancer patients taking chemotherapy, and people who have received an organ transplant) are more susceptible to mold infections.

Possible Health Effects of Mold Exposure

People who are sensitive to mold may experience stuffy nose, irritated eyes, wheezing, or skin irritation. People allergic to mold may have difficulty in breathing and shortness of breath. People with weakened immune systems and with chronic lung diseases, such as obstructive lung disease, may develop mold infections in their lungs. If you or your family members have health problems after exposure to mold, contact your doctor or other health care provider.

Recognizing Mold

You may recognize mold by:

• Sight (Are the walls and ceiling discolored, or do they show signs of mold growth or water damage?)
• Smell (Do you smell a bad odor, such as a musty, earthy smell or a foul stench?)

Safely Preventing Mold Growth

Clean up and dry out the building quickly (within 24 to 48 hours). Open doors and windows. Use fans to dry out the building. (See the fact sheet for drying out your house “Reenter your flooded home”)

 When in doubt, take it out! Remove all porous items that have been wet for more than 48 hours and that cannot be thoroughly cleaned and dried. These items can remain a source of mold growth and should be removed from the home. Porous, noncleanable items include carpeting and carpet padding, upholstery, wallpaper, drywall, floor and ceiling tiles, insulation material, some clothing, leather, paper, wood, and food. Removal and cleaning are important because even dead mold may cause allergic reactions in some people.

• To prevent mold growth, clean wet items and surfaces with detergent and water.
• Homeowners may want to temporarily store items outside of the home until insurance claims can be filed.
• If you wish to disinfect, refer to the U.S. Environmental Protection Agency (EPA) document, A Brief Guide to Mold and Moisture in Your Home at https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home.

Protect Yourself from Mold

If there is mold growth in your home, you should clean up the mold and fix any water problem, such as leaks in roofs, walls, or plumbing. Controlling moisture in your home is the most critical factor for preventing mold growth.

To remove mold growth from hard surfaces use commercial products, soap and water, or a bleach solution (https://www.cdc.gov/mold-health/about/index.html) of no more than 1 cup of bleach in 1 gallon of water. Use a stiff brush on rough surface materials such as concrete.

If you choose to use bleach to remove mold:

• Never mix bleach with ammonia or other household cleaners. Mixing bleach with ammonia or other cleaning products will produce dangerous, toxic fumes.
• Open windows and doors to provide fresh air.
• Wear non-porous gloves and protective eye wear.
• 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. Although focused on schools and commercial buildings, this document also applies to other building types.
• Always follow the manufacturer’s instructions when using bleach or any other cleaning product.
• More information on personal safety while cleaning up after a natural disaster is available at: https://www.cdc.gov/floods/safety/floodwater-after-a-disaster-or-emergency-safety.html

If you plan to be inside the building for a while or you plan to clean up mold, you should buy an N95 mask at your local home supply store and wear it while in the building. Make certain that you follow instructions on the package for fitting the mask tightly to your face. If you go back into the building for a short time and are not cleaning up mold, you do not need to wear an N95 mask.