In recent years the courts saw an increasing number of lawsuits filed claiming injuries from so-called “toxic mold.” While the number of such cases seems to be decreasing, landlords and property managers should take proactive steps to avoid mold claims and be prepared to defend such claims if they are filed.

Preventing mold claims

Mold is pervasive in the environment. There are more than 100,000 known species of mold and probably a similar number of species not yet cataloged. There is almost always at least some background level of various types of mold spores in both outdoor air and indoor air, the levels varying depending on environmental conditions.

There are four critical requirements for mold growth:

• Available mold spores
• Available mold food
• Appropriate temperatures
• Considerable moisture

The removal of any one of these items will inhibit mold growth. Unfortunately, the first three are virtually impossible to control for the following reasons:

• Mold Spores: Ranging in size from 3 to 40 microns (human hair is 100-150 microns), mold spores are ubiquitous – they are literally everywhere. There is no reasonable, reliable and cost-effective means of eliminating them from human environments.
• Mold Food: If all three other requirements are met, almost any substance that contains carbon atoms (organic substance) will provide sufficient nutrients to support mold growth. Even the skin oil that is left when a person touches an otherwise unsuitable surface, like stainless steel, or the soap residue left from a good cleaning, will provide sufficient nutrients to support the growth of some molds. And many of the most common materials found in homes like wood, paper and organic fibers are among the most preferred of mold nutrients. Thus, eliminating mold food from human environments is virtually impossible.
• Appropriate Temperatures: Unfortunately, most molds grow very well at the same temperatures that humans prefer. In addition, anyone who has cleaned out their refrigerator quickly realizes that temperatures close to freezing are not cold enough to prevent mold growth, and temperatures that are much warmer than humans prefer, like those of the tropics, will grow abundant quantities of mold. Therefore, it is not feasible to control mold growth in human environments through temperature control.

This leaves the Considerable Moisture requirement for mold growth, and happily this is something that is subject to human control in order to minimize and prevent mold growth. The various species of mold have different water requirements, but the vast majority of mold species require moisture in the material on which they grow corresponding to a relative humidity of at least 70%. In fact, the great majority of serious mold outbreaks inside buildings occur where porous, cellulose-type materials have literally been kept wet by liquid water or sustained condensation.

Thankfully, humans prefer humidity below the critical relative humidity for mold growth. Thus, of the four basic requirements for mold growth, moisture availability is the only feasible mold growth requirement to control in human environments. Therefore, the consensus is that effective mold control strategies consist of the combination of:

• Reducing the availability of moisture, and
• Killing and removing active mold growth colonies

Following is a summary of practices that will minimize mold growth:

1. Air Conditioner Operation: Advise tenants to always set the fan mode switch of a central air conditioner in the AUTO position, never in the ON position. Why? When set to the ON position the blower fan runs continuously and the moisture which has condensed on the air conditioner’s evaporator coil during cooling is re-evaporated and blown back into the unit before it can drain off the coil. This causes relative humidity to be significantly greater than if the air conditioner fan mode switch is set to the AUTO position.
2. Air conditioner sizing: Oversizing of air conditioners is common. The more an air conditioner is oversized, the poorer its humidity removal performance, especially at higher thermostat settings. This is because, during each air conditioning on cycle, the moisture removal does not reach full capacity for about the first three minutes of operation. The more the system is oversized, the shorter the on-cycle during which moisture is removed.
3. Air Conditioner Thermostat Set Point: Set the summertime thermostat to the highest temperature that is comfortable. A temperature of 78 F or greater is recommended. Setting the thermostat temperature lower does two things that are counter to the goal of reducing moisture. First, it actually slightly increases the indoor relative humidity. Second, and more important, it decreases the temperature of the materials in the living spaces, thereby significantly increasing the potential for actual moisture condensation on those materials.
4. Interior Doors: Interior doors should be kept open when air conditioning unless the heating and cooling system has a fully ducted return air system from each room of the home or unless specific and sufficient return air transfer pathways have been installed to ensure that closed interior doors do not result in space depressurization problems in the home.
5. Space Pressurization: It is important that homes in hot, humid climates be pressurized slightly with respect to outdoors. The reason is fairly straightforward but not very obvious. If homes are depressurized with respect to the outdoors, then hot, humid outdoor air will be pulled through the very small air pathways that exist in all building envelopes, where it is likely to condense on the cooler surfaces inside (including on the back side of drywall).
6. Vinyl Wall Covering: Impermeable interior surfaces like vinyl wall coverings can result in severe mold problems in hot humid climates. Moisture coming from outdoors can accumulate within the drywall that is behind the vinyl wall covering.
7. Bathrooms: Most bathrooms, particularly tile in and around showers and tubs is regularly wet. As a result, most bathrooms grow mold and require regular cleaning. A weak solution of water and common household bleach can be used to regularly clean these areas and keep them free of mold. Low-noise bathroom fans are also recommended to remove excess moisture during periods when it is being generated by bathing or showering. (See also exhaust fans.)
8. Open Windows and Whole-House Ventilation Fans: Open windows and use of whole-house ventilation fans should be avoided when it is humid outdoors.
9. Air Conditioner Maintenance: Filters should be changed regularly, and air conditioners should be professionally serviced annually to make sure the coils are clean, the condensate drains properly, and the drain pan has no mold.
10. Exterior Water Management: Redirect water away from the unit’s exterior. Set sprinklers so they don’t spray on exterior walls. Do not landscape in a way that directs water flow towards the unit. Use gutters. Keep down-spouts free of debris and direct outflow away from the home.
11. Small Leaks: Even small water leaks will cause mold problems. Plumbing leaks and rainwater leaks from improperly flashed windows, wall and roof penetrations should be promptly repaired. Periodically inspect under sinks and vanities for signs of water leakage.
12. Water Damage: Water damage from flooding or other major water intrusion in homes should be dried within 24 hours if at all possible. For severe flooding and severe water damage for more than 48 hours, a trained restoration professional should be consulted regarding cleanup procedures.
13. Exhaust Fans: Make sure the clothes dryer vent goes all the way to the outside of the home, not to the crawlspace or to the inside of the attic or the house. The same goes for bathroom vent fans. It is also important for the kitchen range hood to vent to the exterior. Recirculating stove and kitchen vents provide no removal of stovetop moisture and inferior control of cooking-related pollutants compared with venting completely to the outdoors. Kitchen and bath exhaust fans should only be used while cooking or using the bathroom to remove excess moisture generated by these activities.
14. Closets: Mold likes like the dark, and closets are rarely supplied with conditioned air as a standard part of air conditioning systems. As a result it is not uncommon to have mold or mildew occur in closets, especially on leather. Leaving closet doors open to provide more conditioned air circulation or leaving the closet lights on with the door closed so as to raise the temperature (which lowers relative humidity) can reduce these problems.
15. House Plants: Minimize live house plants, especially if there is difficulty controlling the relative humidity in the unit.

To prevent mold claims by tenants, it is recommended that landlords incorporate mold-related information and requirements into Rules and Regulations which are incorporated into the lease. A suggested format follows (which should be revised appropriately based on the foregoing information and particular characteristics of the unit being leased):

Suggested mold-prevention rules for tenants

Mold spores are present in the environment, both indoors and outdoors, and cannot be eliminated. Excess moisture is the primary cause of mold growth indoors. Most sources of moisture, however, can be controlled by simple procedures under the tenant’s control. The landlord will not be liable and tenants will be responsible for all personal and property damage resulting from their failure to comply with these guidelines:

1. Minimize humidity in your rental premises.

a. When central air conditioning is in use, set the fan switch to AUTO rather than ON. When set to the ON position, the blower fan runs continuously and the moisture which has condensed on the air conditioner’s evaporator coil during cooling is re-evaporated and blown back into the unit before it can drain off the coil.

b. When central air conditioning is in use, set the temperature to the highest comfortable level, preferably at least 78 degrees. Lower settings can cause condensation on interior surfaces.

c. Allow at least one inch between the furniture and walls to aid ventilation.

d. Open closet doors to allow ventilation.

e. Use the bathroom fan during and for 10 minutes after bathing or showering. If no fan is available, open the bathroom window slightly for the same duration.

f. Use the fan in the laundry area during and for 20 minutes after using the washer or dryer. If no fan is available, open a window slightly for ventilation during the use of the appliances and for a little while after use as deemed appropriate.

g. Use the exhaust fan above the stove or open a window slightly whenever cooking, especially if steaming.

h. Use a dehumidifier during humid months as applicable.

i. Cover fish tanks.

j. Do not keep an excessive number of house plants.

2. Clean thoroughly and regularly. The following is the cleaning method recommended by the EPA:

a. Mold growth can be removed with commercial cleaning products or a weak bleach solution (one cup bleach in one gallon water).Wear gloves during cleanup and be careful not to spread the mold. Sensitive people who have to cleanup mold should wear a tight-fitting face mask.

b. Use mold killing products when cleaning kitchens and bathrooms.

c. If mold or mildew appears on walls, ceilings, floors or around tubs or sinks, immediately remove the mold or mildew.

d. Dry any water that spills from showers, tubs or sinks immediately.

e. Clean up spills onto carpets, rugs or floors and thoroughly dry the rug or carpet.

f. Regularly check and clean the windows and window tracks and keep free of condensation.

3. You are obligated to notify the landlord immediately of excess moisture problems such as rainwater or groundwater leakage, leaking plumbing, leaking tubs or showers, or running toilets. If you have attempted to clean mold or mildew and it reappears quickly or you are not able to remove it, report the problem to the landlord immediately.

Defending mold claims

In the past 20 years or so, there was an explosion in the number of mold claims, some resulting in substantial judgments against landlords. Although the number of such claims seems to be decreasing currently, it is clear that much of this litigation was fueled by a great deal of misinformation and “junk science” readily accessible on the Internet. For example, a current Google search on the term “toxic mold” results in about 28 million “hits.”

The surge in mold litigation led many insurers to decline to provide coverage for mold claims, thus eliminating what otherwise would be a primary line of defense against such claims. Even when insurance is available, this writer has observed that insurers are inclined to settle mold claims quickly rather than spend time and money defending them – which has the perverse effect of encouraging such claims.

Fortunately, the consensus in the medical and scientific communities is coalescing around some conclusions which make it relatively easy to defend most mold claims. Perhaps the most important conclusions of the medical experts are:

1. That exposure to airborne mold spores has no permanent adverse health effects. Rather, the effects are short-term and are abated when the mold exposure is reduced or eliminated. The primary short-term effects are allergic reactions and aggravation of pre-existing asthma conditions in sensitive individuals.
2. That individuals sensitive to molds are sensitive only to some molds and not all molds.
3. That reliable medical testing for mold sensitivities requires skin prick tests and blood tests for IgE and IgG antibodies.

These conclusions are expressed in an article titled “The Medical Effects of Mold Exposure” published in the Journal of Allergy and Clinical Immunology in February 2006. This article was described in a relatively recent court decision as the best summary of current mainstream medical opinion on the subject.

The scientific/medical community also is in broad agreement that stringent protocols must be observed to achieve accuracy in testing for airborne mold spores. The recommended protocols require testing not only indoor air, but also the outdoor air in the immediate vicinity of the building to determine whether background levels of mold differ markedly in the indoor air. The protocols also require multiple tests over a period of several days to ensure that transient conditions have not unduly affected the test results. Conducting tests according to these accepted protocols is quite expensive, and most air-testing companies do not follow these protocols.

The foregoing discussion provides several points of attack when defending mold claims. In essence, in order to prove a mold claim, a plaintiff will have to present the following evidence:

1. That mold spores of one or more particular species were present in excess quantities in the air in the leased premises, which will require expensive testing for airborne mold according to accepted scientific protocols. Further, both the company which performed the actual air testing and the laboratory which analyzed the air samples would have to provide witnesses to testify to their work and the results in order to avoid hearsay problems.
2. That the plaintiff has an allergic sensitivity to the particular species of mold revealed by the airborne mold testing. As noted above, this would require skin prick testing and blood tests for IgE and IgG antibodies. A medical expert, or at least the medical records custodian of the testing facility, would have to testify about the test procedures and results in order to avoid hearsay problems.
3. That the plaintiff suffered adverse health consequences as a direct result of exposure to the specific species of airborne mold to which he or she has an allergic sensitivity and to which he or she was exposed. This “causation” element would require the expert testimony, within reasonable medical certainty, of a physician with sufficient expertise in the area.

If the plaintiff fails to establish any one or more of the three points listed above, the plaintiff’s claim should fail. And it will be difficult, if not impossible, for most tenants to prove all of these things, both because they (and their attorneys, if represented) may not understand everything that needs to be proved and because all of the above proof steps require substantial expenditures. Further, in view of the fact that the medical consensus is that mold exposure has no permanent adverse health effects, most attorneys, if representing a plaintiff, will not be willing to advance such expenses because the potential judgment resulting from a short-term illness is small.

Accordingly, at an early stage in a mold lawsuit, discovery questions should be sent to the plaintiff to determine:

• Whether the plaintiff has had skin prick tests and/or blood tests for IgE and IgG antibodies to determine allergic reactions to particular species of mold, and, if so, the results of the tests.
• Whether a physician has expressed the medical opinion that any physical condition of the plaintiff was caused by exposure to mold to which the plaintiff is sensitive.
  • Most of the time it will be found that no such testing has been done and/or that no physician has ventured such an opinion, either of which should be sufficient to get the plaintiff’s claim dismissed.
• What type of testing, if any, was done to determine the presence of particular species of mold. Possible types of tests are “bulk mold” and “airborne mold.”
  • “Bulk mold” testing simply refers to taking a sample of mold from a surface and analyzing that mold to determine its species. Such a test is useless from the plaintiff’s perspective because it does not prove that any mold spores of that species were present in the air (one presumes the plaintiff did not attempt somehow to ingest the bulk mold, and, if he or she did so, it’s hardly the landlord’s fault).
  • If testing was done for airborne mold, what protocols were used and what were the test results.

Most of the time it will be found that no such testing has been done. Even when testing has been done, it often will be useless “bulk mold” testing. Even when airborne mold testing has been done, most of the time it will be found that the appropriate protocols were not followed. If the only testing was for bulk mold, or if airborne testing did not follow the proper protocols, it should be possible to get the plaintiff’s claim dismissed.

Procedurally, the best way to “cut off” a mold lawsuit at an early stage is to file a Motion for Summary Judgment after discovery responses have been received. Such a motion also may require an affidavit from an expert that the claim cannot be established in view of the discovery responses. If granted, the motion will result in dismissal of the plaintiff’s claim.

If, for some reason, the Motion for Summary Judgment is not granted, the foregoing information provides ample ammunition for defending the claim at trial.

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