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Toxic Mold - Overview, Types, and Causes

Toxic mold is an increasingly common problem in homes and commercial buildings. While many people have heard of toxic "black mold," harmful molds exist in a wide variety of forms. Depending on the person exposed, mold exposure may cause ill effects that range from very serious health problems to minor annoyances.

This article provides an overview of the main types of mold. It includes common factors that cause mold in homes and commercial buildings. You can find additional personal injury resources on the following Findlaw pages:

Also, the Health and Safety in the Home section of FindLaw's Real Estate Center contains information and resources on other home health and safety topics, such as lead and radon.

Mold Claims in Personal Injury Law

Toxic mold problems in homes and commercial buildings have dramatically increased in recent years. Many of these problems result in legal claims. Experts and personal injury lawyers who handle mold-related claims give various reasons for this increase. That includes:

  • Increased emphasis on making buildings airtight
  • Hasty construction
  • Faulty building techniques and materials
  • Increasingly complex building designs

While many people have heard of "black mold," a variety of strains can cause ill health effects. Toxic mold exposure can happen to residents and occupants in homes, businesses, and places of employment. If you have been exposed to toxic mold in your home or place of business, you may benefit from this overview.

What Causes Mold in Homes and Buildings?

Mold spores are everywhere in the natural environment. They enter homes and buildings through windows, open doors, pets, or attached to people. Once spores are indoors, they must have abundant moisture, a food source, and a certain temperature range in order to grow.

Moisture infiltration is the main cause of building mold. Moisture may come from a wide variety of sources. Many modern homes and buildings are very airtight. This is great for efficiency, but not so great for allowing the structure to dry. For example, once moisture gets in through a pipe leak, faulty windows, roof leaks, or other sources, the water cannot evaporate. Mold is drawn to this moisture. It may grow on wet materials such as wood, insulation, ceiling tiles, and carpeting.

Sources of Moisture

Moisture can come from a variety of sources:

  • Moisture may enter a building as a result of water damage or water intrusion from flooding. It can also enter through broken pipes or property damage as a result of excessive rain. A malfunctioning air conditioner or poor air conditioning can also encourage moisture buildup. Moisture in a home or building may soak carpeting and other materials, creating a moist food source on which mold may attach and grow.
  • Moisture may also enter a building through walls and living spaces by way of leaks in the roof, walls, or windows. Such leaks may be a result of poor construction, construction defects, faulty design, or faulty building materials.

Regardless of the source of moisture, once water enters a building, mold will be drawn to it. It can feed on ceiling tiles, carpet, insulation, paper backing materials, and drywall. Mold will prefer areas with increased dampness and humidity, such as your basement or bathrooms.


Mold grows in temperatures ranging from 60 to 80 degrees Fahrenheit, especially in high-humidity environments. In colder environments below 40 degrees, mold is unable to grow. However, different types of mold have varying degrees of resistance to temperature changes.

Food Source

Mold can consume most organic matter, going beyond just bread, meat, and cheese. Indeed, mold can even eat into fabrics, wood, wallpapers, earth, and greenery. Even a clean home will inevitably contain a food source for mold. This is why proper airflow is important to reduce the chances of mold growth.

Mold Warning Signs

There are a variety of warning signs that should lead a person to investigate a home or commercial building for potential mold infestation. The earlier an investigation takes place, the better the possibility that a property owner can reduce possible damages and adverse health effects caused by mold exposure.

The following are some warning signs that may indicate the presence of toxic mold:

  • Visible mold growth
  • Discoloration or water stains on internally/externally facing walls or ceilings
  • Areas of standing water or condensation on floors, walls, or window sills
  • "Musty" odor

Types of Mold

Many types of mold may occur in homes and office buildings. Some mold species are considered harmless, while others can cause potentially serious adverse health effects.

The most common mold types found in homes and offices are:

  • Cladosporium
  • Penicillium
  • Aspergillus
  • Alternaria
  • Stachybotrys chartarum (atra or toxic black mold)

Mold has a natural function of breaking down biological materials. Found almost everywhere in our environment, mold travels as tiny spores that are often light enough to float through the air. Mold spores may also stick to pets and humans. When mold spores come to rest on a damp area, they begin to grow and digest the material on which they have landed.

In the end, regardless of whether a particular type of mold produces volatile organic compounds (VOCs) or toxins, all molds should be considered potential health risks. The presence of mold should lead to investigation, cleanup, or removal. Small amounts of mold can be cleaned up with bleach. However, if you suspect any type of mold problem, you should consider enlisting professional help.

Why Is Mold Harmful?

Certain molds produce volatile organic compounds or toxins as byproducts of their metabolism. VOCs generally evaporate at room temperature. In fact, when a person smells a "musty" odor, he or she is actually smelling volatile organic compounds. Some VOCs produce adverse health effects in certain predisposed individuals. In contrast to VOCs, toxins do not evaporate easily. Some are considered very dangerous to humans.

Mold can cause a wide range of health effects on people and pets. Mold creates allergens, which then create allergic reactions. Allergic reactions to mold are common and result in symptoms resembling hay fever, such as sneezing, runny nose, and watery eyes.

Mold may also cause sinus infections, respiratory problems, and asthma attacks. Inhalation of these irritants affects your immune system, weakening your body and making it harder to fight mold-related illnesses.

Illnesses Caused by Mold Exposure

Some of the most common illnesses associated with mold exposure are:

  • Worsening of allergies
  • Respiratory problems
  • Fevers
  • Nasal and sinus congestion
  • Burning and watering eyes
  • Worsening of asthma symptoms
  • Coughing
  • Sore throat
  • Flu-like symptoms
  • Skin irritation
  • Headaches
  • Memory loss

According to the Centers for Disease Control and Prevention (CDC), it is a generally accepted disclaimer that those who are most at risk of illness from mold exposure include:

  • People with allergies
  • People with conditions or diseases that weaken immune defenses
  • People with lung disease
  • The elderly
  • Young children

These individuals are particularly susceptible to hospitalization and may incur medical expenses as a result of exposure. In general, victims of mold injuries may be able to recover their medical bills, depending on the facts of their injury cases.

Get Help If You Suspect a Mold Problem

Mold will grow when there is excessive moisture in a home or commercial building. Adverse health effects and clean-up costs for mold remediation after mold exposure can be devastating. If you discover a mold problem, an insurance company might deny your warranty policy. They might issue a bad-faith denial of your claim. You should consider consulting a toxic mold attorney who can advise you regarding your legal options and plaintiff's remedies.

In light of complex scientific evidence associated with toxic mold cases, toxic mold lawsuits are complicated and may require expert witness testimony. There are also “statute of limitations" laws limiting the time you may file a personal injury claim. A client relationship with a mold litigation law office is the best way to ensure that your legal rights are protected. Search for an experienced toxic mold personal injury attorney near you.

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