Story last updated at 5/6/2009 - 11:10 am
Mold is a problem that spans generations. In fact, there is reference to mold in the Bible. Leviticus 14:45 states: "A house desecrated by mildew, mold, or fungus would be a defiled place to live in, so drastic measures had to be taken." The presence of mold in houses can cause structural damage and health problems. If mold is detected it should be removed immediately.
Living in Southeast Alaska, we are all too familiar with mold. Exposure to mold is common both inside and outside our homes. It's everywhere. Outside, mold can be found on our cars, stairs, walkways, in our gardens, and well, on just about everything. When mold moves into our homes, however, is when we are most at risk.
I receive a number of phone calls and emails from clients wanting to diagnosis whether or not what they are seeing in their homes is mold, how to determine the best and safest methods for removing the mold, and how to keep the mold from returning. In this space over the next few months, I will provide research-based information that addresses these issues because, "People should not live in moldy houses!"
What is mold?
Molds are fungi. They are microorganisms that occur naturally in nature and in large quantities. Molds help break down dead biological materials and can be found growing on soil, foods, plant matter and other items. Molds thrive on organic materials like natural fibers (such as cotton and wool), paper, leather, wood, or surfaces coated with the slightest amount of organic matter such as food, grease and soil. Molds that continue to grow can eventually eat away the organic medium that is their source of food. Wood structural materials and textiles can deteriorate when mold is allowed to thrive on them. Mold and people don't live together well. When mold is found inside housing units, it should be removed for the long-term health and comfort of the occupants.
Why is mold in my home?
The conditions in your home support mold growth. Molds grow best in warm temperatures, 77 to 86 degrees Fahrenheit, though some growth may occur anywhere between 32 and 95 degrees.
Mold requires moisture to thrive, so it may begin growing indoors when mold spores land on surfaces that are wet. Moisture can come from water leaks, flooding, high relative humidity and condensation. Materials that are exposed to a constant leak or have been soaked and not dried thoroughly can support mold growth.
You can unknowingly bringing mold into your house as well. For instance, if mold is found on your winter firewood supply, the spores will become airborne when you bring the wood inside. Burning the wood kills the mold spores, but by that time they may have found a moist area in which to grow. Some molds can take hold and form a new colony in one or two days on damp materials.
Molds require oxygen, but not light, for growth. Mold growth can continue indefinitely without light.
Where would mold be most likely to grow in my home?
Generally, mold may be found anyplace where moisture or relative humidity levels are high.
Crawlspaces built over uncovered earth can have mold problems when the moisture in the ground causes dampness in the space.
In laundry rooms, unvented clothes drying produces high levels of relative humidity that support mold growth. Damp towels and clothes in laundry hampers, washers or dryers can develop a fungus- producing mildew.
In bathrooms, large amounts of moisture can remain in the shower or tub if an exhaust fan is not used. Soap scum on bath and shower walls is a nutrient source for mold growth.
Humidifiers can raise the relative humidity high enough that mold will grow, especially in the winter in areas where there is little air movement. Dark patches of mold can sometimes be seen inside the upper corner of a closet on an outside wall or behind furniture placed against outside walls. Window condensation can result in mold growth where the moisture runs onto the sill or wood trim.
In kitchens, mold growth can be found on the walls if cooking involves large amounts of boiling water and no exhaust fan is used. Cooking that spatters food and grease film on walls, combined with the high humidity levels in those areas, are prime for mold growth. Additionally, the floor pans that collect condensation from automatic defrosting refrigerators are often found to have mold growing in them.
Spills or leaks, such as a sink or toilet overflow onto carpet and other flooring materials, can cause those materials to become moldy.
Flooded and fire-damaged houses that have had water-soaked carpeting and other materials often have mold growth starting within a day or so after being soaked.
Hopefully, you've recognized the common denominator here. The important factor in dealing with these conditions is understanding that mold is not the problem - moisture is. Moisture control translates into mold control; mold is merely the inevitable result.
Next month's installment will focus on types of health problems caused by or related to the presence of mold and how to determine whether mold is present in your home. For resources on mold problems and environmental health, contact the Juneau District office at 796-6221.
Sonja Koukel, PhD, is an assistant professor in the Health, Home & Family Development Program for the Cooperative Extension Service UAF Juneau District. Reach her at firstname.lastname@example.org or 796-6221.