Where does indoor mold come from?
Mold and where it originates
Mold has been a major factor in Indoor Air Quality (IAQ) concerns in buildings for the last several decades. Contrary to common belief, molds do not magically appear in buildings. They can’t penetrate through intact walls or other intact surfaces. They are in the air, or carried into a building on clothes, open doors, and windows, or any opening—very small ones in fact, and settle on a surface with ideal conditions for growth (moisture, heat, food source).
I just heard a statement “yes they can come through walls – they are growing on the walls in my basement”. Not true-molds have the physical size and can’t penetrate through a solid intact well. What this person was seeing is mold that was in the basement air which attached itself to the wall. The moisture from outside the wall penetrated to the inside giving the mold the moisture it needed along with the drywall paper as wood-and began to grow.
Molds are among the earliest known life-forms; they are found in all parts of the world, including Antarctica (“Scientists Tackle Antarctica Mold,” Peter Rejcek, editor, Antarctica Sun, February 4, 2007). They do not have mouths or digestive tracts. Instead, they release digestive enzymes that break down paper, fruits, leaves, shoe leather, bacon or anything else they have landed on and can use for food. The molds then absorb the liquefied food.
According to Olson, fungi and other primitive life-forms go back at least 2.8 billion years [Olson, J.M. (2006), “Photosynthesis in the Archaean Era,” Photosyn Res. 88(2):109-17]. They are one of the oldest life-forms on earth.
Molds reproduce through the microscopic spores which are released to the air. If they settle on a surface that has the right amount of water and food and is at the right temperature, the spores will “germinate” and create a “stem” called a mycelium. Branches called Hyphae form along the mycelia. At the end of the hyphae (in most molds) a “fruiting body” forms. More spores are created in the fruiting bodies and are released when conditions are right, thus starting the whole process all over again.
Since mold spores are found in the earth’s atmosphere all over the world, there is no practical way to eliminate all mold spores from the indoor air. But we can control their growth in places they are unwelcome—your bathroom, cellar, kitchen and so on. Since we can’t eliminate the things mold uses for food, sheetrock, wallboard, rugs, paper, bread, cheese, bananas, and the like, we are really left with only one practical solution—control the moisture that is so essential for mold growth.
Obviously, in the wake of a major storm, there’s nothing we can do to prevent flooding or leaking roofs from making available all the moisture a mold might need to grow and multiply. But under normal conditions, we can use dehumidifiers, we can vent the warm moist air from a clothes dryer, find and repair water leaks or condensation, clean-up water and dehumidify, immediately after a storm. By eliminating the excess moisture, we can prevent the growth and spread of mold.
What if you have had a broken water pipe or a flood? In this case, there is a strong likelihood that a large amount of water will be present for a significant amount of time, fully saturating walls, rugs, furniture, and other items. Most of these will develop visible colonies of mold growth in a few days. The combination of water damage and mold growth will likely require the replacement of these items. Some things, like area rugs, may be salvaged if the visible mold can be removed and the item thoroughly dried, but the majority of soaked, absorbent items will have to be discarded.