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What Conditions Encourage Mold Growth?

Allison Boelcke
Allison Boelcke

Mold is a type of fungus that begins as small spores that multiply when exposed to environments supporting their development. As the spores reproduce, they attach onto an item and form a mass that can be fuzzy or slimy. Mold can grow in a range of colors, such as black, gray, or green, and may develop either indoors or outdoors. If a person is exposed to mold, he or she may experience respiratory problems from inhaling the mold spores. Certain conditions are more likely to encourage mold growth, but identifying and altering the environment can prevent mold from recurring.

One of the most common environmental sources that generally contributes to mold growth is excessive moisture. Areas with accumulated confined moisture sources make mold spores more likely to thrive and multiply into larger growths. Conditions that are more likely to create mold include pipes that continually leak water, wet clothes or other items that are folded or crumpled up, or not drying bathroom floors after showering or bathing. If mold grows on a material that is absorbent, like sponges or carpeting, the items will not be able to be cleaned sufficiently to remove all mold spores and will typically need to be discarded to prevent future mold growth.

Saunas often get mold growth.
Saunas often get mold growth.

Humidity is another condition that can encourage mold growth. In humid areas, the air is filled more heavily with moisture, which makes the environment more susceptible to mold growth, even if the area does not have leaks or other accumulated water. Places that are constantly damp, such as basements or bathrooms, tend to be the household areas most affected by mold. The amount of humidity in an area can be reduced by introducing cooler air, such as through the use of a fan or ventilation system.

Damp environments, such as basements, encourage mold growth.
Damp environments, such as basements, encourage mold growth.

Mold growth is not just confined to indoor environments. The outdoor environments that may encourage mold development are usually dark areas, such as underneath shady trees or plants. A common place for outdoor mold is on damp, decomposing leaves and plants.

Some places that tend to be the most likely to suffer from the development of mold include greenhouses, construction sites, old wooden buildings, flower shops, or saunas. Buildings that have carpeting in areas with drinking foundations are also at a higher risk for mold if any water spills and accumulates onto the carpet. If a small amount of mold growth is found, a person can typically remove it with cleaning products. For widespread areas of mold, it may not be safe for an untrained person to clean it, so a professional may be required.

Discussion Comments


@ElizaBennett - It's actually really easy to control the growth of mold in a kitchen sponge. If you have a dishwasher, put the sponge in the dishwasher. Afterwards, wring it out thoroughly and put it in the microwave on high for sixty seconds. Careful taking it out - it will be very hot!

The hot water from the dishwasher will kill the mold, and the microwave finishes the job. Microwaving will also help your sponge dry out faster. If you do not have a dishwasher or want to freshen your sponge quickly, you can try the microwave alone.


I've had a lot of success with stopping mold growth in my bathrooms by taking steps to control the moisture. One of our bathrooms has an exhaust fan, so we run that for a while after every shower to clear out the excess humidity - especially if the AC or heat isn't running.

The other bathroom has no fan, but it does have a window. Leaving that open after a shower seems to be helping with the moisture. That bathroom has problems with mold growing on the ceiling as well as in the shower area (yuck).

I'm not having much luck keeping mold from growing in my kitchen sponges, though. What works for those? They never get completely dry, so they are a perfect haven for mold.

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    • Saunas often get mold growth.
      By: omicron
      Saunas often get mold growth.
    • Damp environments, such as basements, encourage mold growth.
      By: Steven Baines
      Damp environments, such as basements, encourage mold growth.