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Mold in the home? Is it a health problem? Medical News Today explains

For many people, January is a cold and damp month. During the winter, activities at home can lead to increased humidity and moisture indoors and, unfortunately, this can lead to the growth of mold.

Indoor mold growth is a common problem and is most likely to occur during the fall and winter months.

Walls, clothes, books, toys and even CDs - nothing is sacred when it comes to mold growth. Its seemingly insidious growth can turn prized possessions into musty, moist sadness that only look fit for the garbage.

But for all its corrupting menace, to what extent should we be worried about mold when it invades our homes? If these are the effects that it can have on our possessions, what effects can it have on our bodies?

In this spotlight feature, we take a look at precisely what mold is, what causes it to grow, whether it is bad for our health and, if so, what can be done to stop it.

What is mold?
Molds are a form of fungus. There are many different molds and they can be found both indoors and outdoors. Molds spread through the production of spores, which are present in all indoor environments and cannot be removed from them - spores are capable of surviving in harsh conditions that otherwise prevent the normal mold growth. Molds grow best in moist, warm and humid environments - easily created in the home during the winter. When mold spores land on a damp spot they can begin to grow, digesting the material they are growing on as they do so. Molds are capable of growing on a variety of different surfaces, including fabric, paper and wood.

Common indoor molds include:

  • Alternaria - found in damp places indoors, such as showers or under leaky sinks

  • Aspergillus - often found indoors growing on dust, powdery food items and building materials, such as drywall

  • Cladosporium - capable of growing in cool areas as well as warm ones. It is typically found on fabrics and wood surfaces

  • Penicillium - typically found on materials that have been damaged by water and often has a blue or green appearance.

Molds take a variety of forms and textures, appearing as white, black, yellow, blue or green and often looking like a discoloration or stain to a surface. They can also have a velvety, fuzzy or rough appearance, depending on the type of mold and where it is growing.

How does mold get into our houses?

Mold spores, invisible to the naked eye, can be found everywhere, both indoors and outdoors. Spores make their way into the home either through the air or after attaching to objects or people. Open windows, doorways and ventilation systems are all gateways through which spores can enter. Clothing, shoes and pets can all facilitate the arrival of mold within the home.

Mold will only grow if spores land somewhere that has the ideal conditions for growing - places with excessive moisture and a supply of suitable nutrients. If this does not happen, molds do not normally cause any problem at all. Mold can often be found in areas where leakages and flooding have occurred and near windows where condensation builds up. Wet cellulose materials are most supportive of mold growth, including paper products, cardboard, ceiling tiles and wood products. Wallpaper, insulation materials and upholstery are other typical launchpads for mold growth. Mold growth is usually noticeable - it is usually visible and often produces a musty odor. The World Health Organization (WHO) report that 10-50% of indoor environments in Europe, North America, Australia, India and Japan are estimated to be affected by indoor dampness. This figure suggests that mold could be a highly prevalent issue in locations spread across the world. In North America, the US Environmental Protection Agency (EPA) state that "if mold is a problem in your home, you should clean up the mold promptly and fix the water problem." But do the EPA recommend dealing with mold swiftly because of the damage it can do to property? Or because of the damage it could do to health?

Potential effects of mold on health
"Mold exposure does not always present a health problem indoors," state the Centers for Disease Control and Prevention (CDC). "However some people are sensitive to molds."

Meanwhile, the WHO say that a moldy environment is associated with and could worsen indoor air pollution - a risk factor for certain respiratory conditions:

"Excess moisture on almost all indoor materials leads to growth of microbes, such as mold, fungi and bacteria, which subsequently emit spores, cells, fragments and volatile organic compounds into indoor air. Moreover, dampness initiates chemical or biological degradation of materials, which also pollutes indoor air."

Molds can produce a number of substances that can be harmful. Allergens, irritants and mycotoxins - potentially toxic substances - can affect individuals who are particularly sensitive to them.

In particular, the EPA state that exposure to molds can irritate the eyes, lungs, nose, skin and throats of individuals, even if they do not have a mold allergy. Mold allergies produce similar symptoms to other allergies to airborne substances affecting the upper respiratory tract, such as pollinosis.

These include:

  • Blocked/runny nose

  • Itchy nose

  • Itchy throat

  • Sneezing

  • Watery eyes

In addition, people with a mold allergy that also have asthma are at an increased risk of having their asthma symptoms triggered by a moldy environment, according to the CDC.

However, Prof. Stephen Spiro, the deputy chairman of the British Lung Foundation in the UK, informed MNT that the presence of indoor mold can go further than simply exacerbating pre-existing conditions:

"Certain mold species can cause serious lung infections and scarring. For instance, in some asthmatics, inhaling the spores of a species of mold called aspergillus can lead to a condition called allergic bronchopulmonary aspergillosis, which can impact on the breathing."

Individuals whose immune and respiratory systems are already weakened by chronic conditions would appear to be more susceptible to adverse effects from indoor mold. Prof. Spiro also told MNT that among patients with certain blood disorders, inhaling mold could even lead to fatal complications. Although more conclusive evidence is required, the CDC report that some research suggests there could be an association between indoor exposure to mold and the development of respiratory conditions in otherwise healthy people.

In 2004, the Institute of Medicine (IOM) reported that there was enough evidence to connect indoor mold with the develo