indoor mildew

Controlling indoor mold and mildew

Did you know that most Americans spend 90% of our time indoors? And that number is even higher for the very young, very old and disabled among us. Unfortunately, things like synthetic building materials, cleaning supplies and pesticides can all contribute to elevated air pollution levels in our homes, schools and businesses.  Plus, humid areas like here in Florida have yet another common but potentially dangerous, indoor air toxin to be aware of: mold.
Mold (also called mildew) is sneaky and is often difficult to spot. It likes to hide in your kitchen, bathroom, A/C ductwork, shoes and other dark and damp places. Molds can even grow on clothes, toys, wood, paper, inside walls, under carpets and anywhere there is moisture and dirt.

mold info What are the signs of mold in house, school or office?

If the indoor air smells earthy or musty or if you can see mold or moisture damage, you probably have problems that need to be addressed.

mold info What are the symptoms of mold sickness?

How each of us responds to mold exposure depends on many factors:

  • Our sensitivity to mold
  • Our general health
  • The amount of mold
  • Length of exposure
  • While mold exposure isn't healthy for anyone, people with low mold sensitivity may experience nothing at all.
  • People with mold allergies (believed to be 10% of the general population) may experience a wide range of discomforts from the sniffles, runny nose, red eyes and sneezing associated with hay fever to shortness of breath, fatigue, fever and/or headaches. It is the body's immune response to this foreign but often harmless invader (mold and mold spores) that's more of a concern than the actual presence of the mold. Allergic reaction is the most common health problem associated with mold exposure.
  • People who suffer from asthma may have an asthma attack since mold spores are so small they can travel to the lungs.
  • People who are immune compromised or have a chronic lung illness are more at risk for developing serious lung, or even systemic, infection.
Eating some types of mold has the potential to poison you, but the health consequences of skin contact with mold toxins is still debated.

Where to look for mold in your house

Look for pipes and other places that drip or leak, or where there is moisture. Areas that are often damp, humid or wet can be ideal breeding grounds for mold. If you discover leaks in your home, get them fixed. Dry the moist places. As much as possible, keep your home dry and cool to prevent mold from growing and spreading.

(Note: Our goal is not to dry ALL humidity from the air since this can be harmful to plants, clothing, pets and our health. In general, an indoor humidity level of between 30-60% is considered to be optimal. Use a hygrometer or relative humidity meter to check moisture levels in your home. )

Here are some room-by-room suggestions to help keep your home mold free.

mildew in kitchenKITCHEN

  • Regularly clean your refrigerator drip pan.
  • Regularly remove garbage to prevent odors and spoilage.
  • Dry condensation around windows and doors.
  • Open windows or use exhaust fans when cooking.

mildew in bathroomBATHROOM

  • Allow wet, damp rags, clothes, towels or shoes to dry before storing.
  • Quickly fix any water leaks.
  • Open windows or use exhaust fans when taking baths or showers and for 10-15 minutes afterward. (Fans should vent to outdoors rather than the attic, living areas or crawl space.)
  • Dry shower curtains, doors, tracks and walls after showers and baths.

mildew in living roomLIVING ROOM

  • Open draperies, shades or blinds to let the sun shine on carpets.
  • Reduce the number of potted plants in your home since soil is a good place for mold to grow.
  • Frequently clean home accessories (area rugs, curtains, upholstery, bedding, etc.) and keep them dry.

mildew in laundryLAUNDRY AREA

  • Promptly remove lint every time the clothes dryer is used.
  • Hang wet laundry outside.
  • Make certain that laundry is completely dry before putting it away.
  • When using laundry dryer, allow clothes to cool before storing.
  • Vent the clothes dryer to the outside.

attic humidity problemATTIC

  • Inspect and repair any roof leaks or other places where water may enter your home.
  • Make sure the attic is insulated and has ventilation (soffit and ridge vents are recommended and attic fans help).
  • Do not bring furniture, clothing, books, etc. that have been stored in a moldy place into your home.

crawl space humidityCRAWLSPACE

  • Cover bare soil in a crawl space with 6-mil polyethylene plastic. (Weigh plastic down along foundation walls.)
  • Foundation vents should be kept open for cross ventilation.

mildew in bedroomsBEDROOMS

  • Open closet doors so air can circulate.
  • Open air vents and windows to increase air flow.
  • Sleep with windows closed since the concentration of outdoor mold spores goes up as nighttime temperatures go down and humidity increases.

mildew in basementBASEMENT

  • Run a dehumidifier - especially during humid, summer months. (Remove water daily.)
  • Repair leaky pipes and any groundwater seepage.

mildew prevention tipsGENERAL TIPS

  • Routinely clean and replace furnace or air conditioner filters. (HEPA filter are effective at trapping mold spores.)
  • Vacuum and clean your home regularly, especially bathrooms and kitchens.
  • In summer, when relative humidity exceeds 60%, run a dehumidifier or air conditioner. (Be certain A/C condensation drains outside and away from house foundation.)
  • In winter, or in cool areas, run a heater when humidity is high.
  • Do not store firewood inside the home.
  • Gas heaters and gas logs are vented to the outside using approved flue.

mildew around homeOUTSIDE

  • Clean clogged gutters and downspouts.
  • Keep shrubs at least 1 foot away from outside foundation and walls of the home.
  • Keep the chimney clean.
  • Mildew should be cleaned from exterior of house, walls, wood floors or other wood surfaces before repainting or varnishing. Otherwise, mildew can quickly grow through the new coating.
  • Wear a dust mask when doing yard work.

mold info When mold dries out, is it dead?

When visible mold dries out, it dies and will no longer spread. However, any spores (mold's version of seeds) that are left behind can remain viable for months or even years. And dried spores can easily become airborne, disperse and wait for a warm, wet opportunity to grow as new mold -- in as little as 4 to 12 hours! So mold must not only be killed, it must also be removed!

Fortunately, bleach neutralizes spores as it kills the mold -- if the bleach is able to come in direct contact all the way down to the mold roots (which is easy on glass, showers and counter tops but nearly impossible on porous materials such as wood and drywall).

DIY Mold Removal

If the affected area is less than 10 square feet ( and you are careful, you can probably remove the mold yourself (after addressing the source of the moisture problem). However, if your home has a serious mold problem or you have very young, very old or immune-compromised people living in the home, NEVER TOUCH IT. Contact your local health department.

  • Wear waterproof gloves.
  • Cover any exposed skin.
  • Protect your eyes from mold by wearing snug-fitting goggles.
  • If the site has a high mold infestation (for example after a flood), wear a face mask approved by NIOSH (National Institute for Occupational Safety and Health) or a respirator rated N-95 or higher. DO NOT USE A "SURGICAL MASK" OR "DUST MASK." Wear a long-sleeved shirt and long pants.
  • mold info Hard surfaces can normally be cleaned using a soft-bristled brush with a mixture of 1 cup laundry bleach (maximum) to 1 gallon of water. NEVER MIX BLEACH WITH AMMONIA. OPEN DOORS AND WINDOWS TO ALLOW FOR VENTILATION.

    Sensitive to harsh chemicals like bleach? Two, less toxic mold-cleaning options include:
    • Wet area with straight, white vinegar in a squirt bottle or on a cloth, rub as needed and let the vinegar sit. The vinegar smell should go away after a few hours. (In fact, some experts feel that vinegar does a better job than bleach of penetrating deep into porous surfaces, reaching all the way down to the mold roots.) DO NOT MIX VINEGAR WITH BLEACH.
    • 3% hydrogen peroxide in a spray bottle. Spray moldy area, let sit for 10 minutes, scrub clean and wipe dry. TEST SMALL, HIDDEN AREA TO MAKE SURE THIS WON'T DISCOLOR TREATED AREA.

  • Porous items that become moldy, such as drywall, carpeting, ceiling tiles or furniture, may have to be replaced.
  • Click here for tips on removing mold from clothing, ceramic tile, and exterior wood siding.
  • Mold cannot be covered up by paint. It must be removed.
  • If the cleanup is a large or "extensive" job (for example after a flood where a single patch of mold covers an area larger than 3 foot by 3 foot), you may want to hire a professional who is experienced in mold cleanup to do the job.

Sources (Accessed February 11, 2013)
Cleaning clip art:
NC State University, A&T State University, North Carolina Cooperative Extension, Doc: Put a hold on mold
Tennessee Dept. or Health:

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Feedback for Getting Rid of Mold and Mildew in Your HomeAdd Comment
August 7, 2013
It makes sense that you wouldn't want to breathe in mold spores but what is the danger of touching it?
Cal at FloridaHealth
August 8, 2013
Hello Patrick, For people who are highly reactive to mold, exposure can result in skin irritation. For the rest of us, gloves are advised because 1) people often use pretty caustic chemicals like a bleach solution when removing mold and 2) cleanup involves the risk of scratches and cuts.
February 12, 2013
Isn't black mold the one we have to be primarily concerned about?
Cal at FloridaHealth
February 13, 2013
While Stachybotrys mold (commonly referred to as black mold) is potentially dangerous, the CDC advises that all instances of indoor mold should be treated alike. They estimate that there are between 50-100 common types of indoor molds that can trigger health problems. You'll find pretty much everything you could ever want to know about the dangers of indoor mold and how to control or address it at and
September 30, 2014
After hanging clothes outdoor on the line, my mother used to always bring the wooden clothes pins indoors with the dry laundry... never leaving them outdoors until the next laundry day. That seemed like a lot of unnecessary work to me! Now I realize that this keeps the clothes pins from getting gray and dingy... which is probably a sign that mold is growing in the wood of the clothes pins. (You would assume that, if clothes pins are meant to hold wet clothes, they would be treated in some way to prevent the growth of mold.) More and more, I realize how very smart my mother was. :)
November 23, 2018
I want to paint our outside deck but powerwashing and scrubbing off the mold is always a hassle. Is it OK to just paint or stain over the deck mold?
Cal at FloridaHealth
November 26, 2018
Unfortunately, the mold must be killed and removed before sealing or painting. Otherwise, the mold will eat right through paint and continue to grow on your deck. My local Sherwin Williams store recommends that deck boards should be "clean, dry and dull" in order for paint or stain to adhere well to the wood. And, while they offer mold resistant paint additives, the Sherwin Williams staff doesn't normally recommend it for decks that get a lot of moisture exposure: "Mold resistant deck paint may buy you a few extra months but the mold is still going to return."

Now for the good news: 1) Outdoor mold may be unsightly but it's usually not a health concern. 2) An outdoor deck usually doesn't have to be cleaned perfectly. So, don't put off the project because you feel overwhelmed, just clean it as well as you can. 3) While the hardware store sells mold removal products for decks, you also have several pretty safe cleaning options to choose from. Our contractor always suggests using white vinegar for cleaning and killing mold from decks, outdoor siding, etc. Recently, however, I cleaned the moldy areas of our deck with a plastic scrub brush, latex gloves, a solution of 1 cup OxiClean to 1 gallon of water, and a good hosing down after i was done. The wood came out looking great. And, even though it has been a couple months now -- and I still haven't had the time to come back to paint my newly cleaned deck -- the boards still look good.
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