Why does moisture affect mold growth

It is almost impossible to create a mold free space or to keep a space mold free. What we can do — and should do — is control the amount of mold in our indoor environments. In addition, mold can damage or destroy building materials such as the wood or gypsum board in our homes.

Most people are not affected by exposure to mold, unless they are exposed to a lot of mold. Remember, mold is everywhere; we are all exposed to mold every day. If you have asthma, exposure to mold can cause an asthma attack or make your chronic asthma get worse. At this point we do not know if exposure to mold, especially early in life, can lead to the development of asthma. Unfortunately, doctors can test for allergy to only a very few of the thousands of species kinds of molds that exist.

Only a few molds seem to be able to sometimes cause an infection in healthy people; fortunately these molds do not usually grow in buildings. However, people with a suppressed immune system are much more susceptible to fungal mold infections and many of these fungi do grow in wet buildings. Individuals with AIDS, certain types of cancer and those with organ heart, kidney transplants on certain drugs are much more susceptible to fungal infections.

Molds sometimes make powerful chemicals called mycotoxins. We think that molds make these mycotoxins to decrease the growth of other molds and bacteria. Penicillin is a mycotoxin that we use because it can kill certain bacteria. Unfortunately some of these mycotoxins make people sick. Mycotoxins can cause illness when they are inhaled, absorbed through skin or ingested swallowed. Presently we do not know all that much about the health effects of most mycotoxins on humans.

Most of what we know about mycotoxins comes from exposure of farm animals to moldy grain or hay. We cannot easily or reliably measure the level of mycotoxins in air samples to determine exposure levels. The answer is simple: keep your home dry. If mold does not have moisture it cannot grow. Remember mold spores are everywhere so you cannot completely keep them out of your house.

Since our houses are built with wood products and paper faced drywall, food for mold is always present. Mold shares its classification with yeasts and mushrooms.

While bacteria is unicellular, or structurally a one-celled organism, mold is multicellular. However, mold and bacteria do have one thing in common: they thrive in a humid environment. Even though mold can be beneficial in laboratory settings, just like bacteria and viruses, mold is considered a severe threat to human health. Mold spores can perform asexual reproduction by mitosis or meiosis. Mitosis and meiosis are the two types of cell division that cause molds to grow and reproduce.

Fungi are heterotrophic and saprophytic because they cannot produce their own food and must rely on an external food source that is high in cellulose. During reproduction, cells called mold spores are distributed or scattered in the environment.

Mold spores are too small to be detected by the naked eye. You will not notice their presence or be able to avoid exposing yourself to them at the early stage of their existence. Once spores enter the environment, they can end up everywhere inside your home. Hyphae are thread-like structures present in the mycelium. Mycelium is a network of numerous hyphae that make up the multicellular fungi. They are tiny and feathery with rigid cell walls to protect the spores.

Aside from cell walls, the mycelium has septa, or divisions, adding more protection to mold spores. When hyphae release spores into the air, the spores germinate like plant seeds growing into a new hyphae cell, and this process is repeated until many hyphae are formed. This happens fast, especially if the environmental conditions are favorable, such as when the environment contains minimal light, excessive moisture, and a food source is present.

The moisture level required for mold growth is greater than 60 percent relative humidity. Molds gradually destroy the things they grow on. You can prevent damage to buildings and building contents, save money and avoid potential health problems by controlling moisture and eliminating mold growth.

Eliminating all mold and mold spores indoors is virtually impossible, but controlling indoor moisture will control the growth of indoor mold. Moisture problems can have many causes. Some moisture problems have been linked to changes in building construction practices since the s. These practices led to buildings that are tightly sealed but, in some cases, lack adequate ventilation. Without adequate ventilation, moisture may build up indoors and mold may grow.

A building must be properly designed for climate, site location and use, and its design must be accurately followed during construction or the building may have moisture-control problems.

For more information on building construction for moisture control, see the Resource List. Delayed or insufficient maintenance can lead to moisture problems in buildings. Undiscovered or ignored moisture problems can create an environment in which mold can grow. Moisture problems in temporary structures, such as portable classrooms, are also frequently associated with mold problems.

Some moisture problems are not easy to see. For example, the inside of walls where pipes and wires are run pipe chases and utility tunnels are common sites of mold growth. Mold is frequently found on walls in cold corners behind furniture where condensation forms. Other possible locations of hidden moisture, resulting in hidden mold growth are:.

You may suspect mold, even if you can't see it, if a building smells moldy. You may also suspect hidden mold if you know there has been a water problem in the building and its occupants are reporting health problems. Many buildings incorporate vapor barriers in the design of their walls and floors.

Vapor barriers must be located and installed properly or the building may have moisture problems. What is mold though? How does it grow and why? What happens to the surfaces mold grows on? When does this nuisance turn into a hazard? Mold grows on any dead organic matter in nature but is only visible to the human eye when it forms a large colony, called a mycelium.

Unlike colonies of ants or termites, a mycelium is not made up of multiple individual organisms. It instead consists of an interconnected network of hyphae, all part of the same organism. Mold reproduces via the production of small spores. These spores can be compared to the seeds of a plant, though they are much smaller than seeds or even pollen grains.

Their small size makes them easy to disperse via wind and water. They can also travel long distances by clinging on to clothing or fur.