Why Mold Growth Presents Problems In Buildings

Gregory Baker
July 7, 2008 — 1,375 views  
This is the second part of a three-part article that examines how mold is currently being addressed in the United States within the context of evolving standard of care issues specific to moisture-damaged buildings and mold growth.  Part 2 discusses why mold growth presents problems in buildings.  The author - Greg Baker - is a certified industrial hygienist and indoor air quality professional with over 20 years of consulting experience in buildings.  Mr. Baker is an associate with AMEC Earth and Environmental in Portland, Oregon.

Mold has become a major indoor air quality issue and a perceived public health problem in the United States, Canada, and Western Europe.  Mold-laden, moisture-damaged buildings correlate with higher-than-average incidences of occupant complaints and reports of non-specific health symptoms.  Molds and some other fungi cause problems in buildings because they are decomposers.  As long as adequate moisture is available, mold will grow.  Through the process of decay, mold destroys building materials and furnishings composed of organic carbon-based compounds.  

Many biologically-derived particles in the environment are allergens, including pollens, animal dander, and mold.  When these particles become airborne they are called bioaerosols.  Human responses to bioaerosol exposures include irritation, allergic, and pathogenic effects; and under some circumstances, and at some level, toxigenic effects may be possible.

Once mold particles enter the human lung through inhalation, the body's primary response to mold is irritation and possibly a variety of non-specific health symptoms.  When exposed to airborne mold, most people will experience some degree of discomfort or irritation, but few people will experience an allergic reaction.  As a group, asthmatics are an exception; they are more sensitive to airborne particles, and their reaction to a similar mold exposure is likely to be more pronounced and severe.

A few mold species are pathogenic, that is, they are capable of growing in human tissue and causing an infection or disease.  However, mold-caused diseases seldom occur in normal healthy individuals.  Groups likely to be at the greatest risk of developing an infection from exposure to molds are the very young, the very old, and the immuno-compromised.  Today the use of immune-suppressant drugs is widespread, and patients frequently become immuno-compromised during the treatment of a variety of medical conditions.  Burn victims, organ-transplant patients, those undergoing chemotherapy, and those suffering from AIDs are very susceptible to a few species of pathogenic mold.  Aspergillis fumigatus is an example of a potentially pathogenic mold that hospitals monitor closely and diligently control.  Immuno-compromised patients that contract aspergillosis while hospitalized, frequently die from this fungal infection.

What about toxic mold, or black mold?  Is it really that dangerous?  Is "toxic mold" the "next asbestos" or is it merely the latest toxic tort du jour?  "Toxic mold" is nothing more than a term coined by the media - a term with little or no scientific basis.  Many mold species are capable of producing mycotoxins (i.e., fungi poisons) that are bound to their cellular structures.  Unlike volatile organic compounds (VOCs), mycotoxins are not gasses or vapors that can be easily dispersed and inhaled.  Mycotoxins are large molecular weight, non-volatile organic compounds that are incapable of "off-gassing".  For mycotoxin exposure to be possible, they must be inhaled or ingested in particle form (i.e., as dust).

Some strains of Stachybotrys chartarum - the so-called "toxic black mold" - are capable of producing mycotoxins under optimal environmental conditions. The popular press has sensationalized Stachybotrys by labeling it "toxic"; however, the media consistently fails to inform the public that "it is the dose that makes a poison."  In non-industrial and non-agricultural settings - such as schools, homes, and office buildings - it is highly improbable for people to be exposed to enough airborne Stachybotrys to suffer a toxic effect.

In theory, if foods contaminated with Stachybotrys were ingested by a human, the mycotoxins produced by this organism could cause a toxic effect resulting in tissue damage, organ failure, and even death.  However, the unfortunate individual would have to consume a sufficient quantity of the mycotoxin, above and beyond a threshold-level dose necessary to "make a poison".  In buildings impacted by moisture and mold, most occupants typically do not eat foul-smelling, poor-tasting, mold-laden building materials.  For additional information on this subject, refer to the website of the American College of Occupational and Environmental Medicine (ACOEM6).

Mold will only grow indoors when uncontrolled moisture is present in a building.  By design, moisture is supposed to be controlled in buildings, and uncontrolled moisture is supposed to be kept out of buildings.  When mold grows, there is a proximate cause for the property damage that results, usually related to one or more of the following factors: a building defect, poor planning prior to construction, inadequate supervision during construction, lack of maintenance after construction, a catastrophic event, or some other problem.

Recently indoor mold has become a cottage industry for construction defect attorneys, construction defect consultants, mold consultants, mold remediation contractors, and building restoration contractors.  When mold is not managed properly, it can cause major problems for a building owner, property manager, and tenants.  These parties are faced with conflicts of interest.  And any of these "problem solvers" can become part of "the problem", particularly if the situation "turns legal" and is headed towards litigation.

A legal web of responsibilities connects various parties when moisture problems arise in a building.  As a construction project reaches substantial completion and becomes available for occupancy, a number of warrantees, contractual agreements, and regulatory obligations take effect.  These responsibilities oblige all parties to act with reasonable care.  Failure of any party to act with reasonable care (i.e., negligence) can create liability for all.

Mold contamination is very susceptible to personal injury litigation based upon negligence. The theory goes like this.  The conditions that allow for illness from exposure to mold requires negligence.  Negligence only occurs when parties fail to act with reasonable care, and damages result, or are alleged, such as impaired health or economic loss.  Based on this theory the property owner is ultimately responsible for the condition of the building, its environment, and the safety of those who are invited onto the property.  However, all parties that had anything to do with the original construction of the building  - including the design and construction management - can also become entangled in the legal web.  This also applies to any subsequent mold remediation and repair work that may follow.

The legal web of responsibilities dictates that the building owner and others act with prudence and consider various risks.  For example, let's say we remediate a mold-impacted building and are confident that we have done things right.  All parties involved in the design and execution of the repairs may still be named in a lawsuit, particularly if there is a perception that the standard of care was not followed.  The risk of being "forced to defend" remains and the defense costs can be considerable.  Therefore, all parties involved with resolving moisture and mold issues are advised to exercise due diligence and to proceed with an abundance of caution.

Warrantees also can create risk for building owners and others.  State and local codes often imply a "warranty on habitability" regarding landlords and leases.  Although this primarily affects residential properties, it can also apply to commercial properties.  Habitability is defined as "the minimum standard of decent, safe, sanitary housing".  When a building's indoor air quality is impaired and excessive mold is present, these conditions can afford a tenant with "a constructive eviction", which allows the tenants to vacate the property and end the lease.

To make matters worse for landlords and building owners there are several "over a barrel" risk factors that must be considered.  Tenants can sue for personal injury based upon negligent acts and alleged damages.  Again, the landlord may be "forced to defend", even if health-related damages could not be proven (which is usually the case with mold).

In most cases the science just is not solid enough to demonstrate cause (mold exposure) and effect (disease).  There are very few instances where a plaintiff prevailed in a mold-related lawsuit and was also awarded money for personal injury.  Also, defendants - and their insurance providers - are prone to settle out of court; insurance companies are reluctant to risk letting these types of cases go to a jury trial, and owners/landlords often wish to avoid the publicity that their property is likely to receive if a suit goes to trial.

If a perceived or genuine indoor air quality problem goes to press, the property's reputation may become tainted and the owner/landlord stands to lose out.  Replacing tenants and the cash flow they provide may be difficult and time consuming.  Even in instances where tenants obviously have "no case", landlords often decide to take a loss, rather than fight, face bad publicity, and risk the threat of a lawsuit.

Another category of risk for property owners and managers to consider is: owners and tenants are often employers, and employers have a general duty to protect the safety and health of their employees.  If visible mold is present and employees are reporting health symptoms, safety and health regulators may respond, increasing the possibility of regulatory liability.

To complicate matters for landlords and building owners, some states have adopted, or are considering laws requiring notification to potential purchasers of real estate.  Full disclosure of a building's history - related to water damage and mold remediation projects - may be required now or sometime in the future. This type of legislation may impact the value of specific properties, and this scenario has the potential to present conflicts of interest to an owner and a real estate agent who are motivated to sell.

In summary, mold growth has the potential to cause a variety of problems, including property damage, impaired indoor air quality and personal injury.  In addition to possible contractual and regulatory liabilities, those involved with resolving moisture and mold issues must consider standard of care issues.  This is absolutely necessary to minimize the potential for liability associated with negligence.

To be continued next month with Part 3 of 3: How to respond to mold growth once it is discovered.

Gregory Baker

AMEC Earth & Environmental, Inc.