NDSU Extension Service - Ramsey County


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Warm plus Wet equal Mold

Warm plus Wet equal Mold


Our recent wet, wet weather plus rising temperatures create the perfect storm for mold growth.

Common sites for household mold growth include bathrooms, kitchens and leaky basements. Condensation in poorly ventilated attics also can foster mold. Left unchecked, mold can inflict major damage to your home, furnishings and belongings. In rare instances, some molds can cause serious, even life-threatening health problems.


Molds are part of the natural environment. Outdoors, molds play a part in nature by breaking down dead organic matter such as fallen leaves and dead trees, but indoors, mold growth should be avoided. Molds reproduce by means of tiny spores; the spores are invisible to the naked eye and float through outdoor and indoor air. Mold may begin growing indoors when mold spores land on surfaces that are wet.


 There are many types of mold but none of them will grow without water or moisture. It can be easy to miss mold growing in dark corners, under floor tiles or behind wallpaper. Mold may be hidden in places such as the back side of dry wall, wallpaper, or paneling, the top side of ceiling tiles, the underside of carpets and pads, etc. Other possible locations of hidden mold include areas inside walls around pipes (with leaking or condensing pipes), the surface of walls behind furniture (where condensation forms), inside ductwork, and in roof materials above ceiling tiles (due to roof leaks or insufficient insulation). However, the musty smell of many molds often is a dead giveaway.  


Molds have the potential to cause health problems. Molds produce allergens (substances that can cause allergic reactions), irritants, and in some cases, potentially toxic substances (mycotoxins). Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals. Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash (dermatitis). Allergic reactions to mold are common. They can be immediate or delayed. Molds can also cause asthma attacks in people with asthma who are allergic to mold. In addition, mold exposure can irritate the eyes, skin, nose, throat, and lungs of both mold-allergic and non-allergic people. Symptoms other than the allergic and irritant types are not commonly reported as a result of inhaling mold.


If you have mold, exercise care when removing it to avoid inhaling mold particles or spreading them throughout the home:



  • If mold growth covers more than 100 square feet, the Environmental Protection Agency recommends hiring a professional to remove it. People sensitive to mold should not try to remove it themselves if the mold covers more than 10 square feet.
  • Wear rubber gloves and a respirator mask with an N-95 rating from the National Institute of Occupational Safety and Health. Other face masks may not effectively filter airborne mold particles. Inexpensive N-95 masks often are available from hardware and home-improvement stores.
  • EPA recommends using a mild detergent rather than bleach.  Like mold, bleach is a lung contaminant and when cleaning mold with bleach you can have both mold and bleach in your lungs and do double damage.



  • Scrub mold from surfaces with a stiff wire brush.
  • Discard moldy textiles. It's virtually impossible to remove mold from porous materials. Steam-cleaning carpets and upholstery can actually worsen a mold problem by adding moisture to the material.


    To prevent mold problems from returning or occurring in the first place, keep the interior spaces of your home dry and well ventilated:



  • Use exhaust fans in the kitchen and bathroom.
  • Keep indoor humidity at 30 percent to 50 percent. Use a dehumidifier where necessary.



  • Make sure air is flowing properly through household heating, ventilation and air-conditioning systems.
  • Keep water out of your basement or crawlspace by keeping gutters and downspouts clear and making sure the ground around your house slopes away from the foundation.  It is important to dry water-damaged areas and items within 24-48 hours to prevent mold growth.



  • Do not paint or caulk moldy surfaces. Clean up the mold and dry the surfaces before painting. Paint applied over moldy surfaces is likely to peel.

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