Mould Information – Guide

Mould information – With the new technology that is creating air tight homes, Toxic Black Mould has become the new “buzz word” of new home buyers. Horror stories abound, scaring home owners with tales of expensive clean-ups and renovations. Some “home inspectors” have pounced on this fear to capitalize on these fears. Barrie Home Inspection believes an educated consumer makes the best client, so has researched the internet and brought this article for your use. The new generation of children are more subsceptable to allegies and asthma than previous generations.   Mould, which can remain unseen, can adversley affect young childrenand adults with flue like symptoms.

Mould Information – What is Toxic Black mould?

Moulds (and mildew) are fungi. Fungi are neither plant nor animal but, since 1969, have their own kingdom. The fungi kingdom includes such wonderful organisms as the delicious edible mushrooms, the makers of the “miracle drug” Mould Information - Mould Inspection Servicespenicillin and the yeast that makes our bread rise and our fine wines ferment. Biologically, all fungi have defined cell walls, lack chlorophyll and reproduce by means of spores. Approximately 100,000 species of fungi have been described and it is estimated that there are at least that many waiting to be discovered. The vast majority of fungi feed on dead or decaying organic matter – they are one of the principle agents responsible for the natural recycling of dead plant and animal life. The most common fungi are ubiquitous within our environment and we are constantly exposed to them. For the most part, however, diseases caused by these common fungi are relatively uncommon and are rarely found in individuals with normally functioning immune systems. Nonetheless, mould has recently experienced high profile press coverage. There are a variety of inflammatory press reports concerning lawsuits over air quality in homes, courthouses and other buildings; parental concerns regarding school classroom environments; home insurers refusing to cover mould damage; and widely distributed news reports on so-called “toxic mould.” But don’t panic. mould can be managed effectively in most cases and this guide will help you do that. Critical Requirements

There are 4 critical requirements for mould growth – available mould spores, available mould food, appropriate temperatures and considerable moisture. The removal of any one of these items will prohibit mould growth. Let’s examine each requirement, one-by-one.

Mould Spores.  Ranging in size from 3 to 40 microns (human hair is 100-150 microns), mould spores are ubiquitous – they are literally everywhere. There is no reasonable, reliable and cost-effective means of eliminating them from environments that humans inhabit. So, trying to control mould growth through the elimination of mould spores is not feasible.

Mould Food.  If all three other requirements are met, almost any substance that contains carbon atoms (organic substance) will provide sufficient nutrients to support mould growth. Even the oil from your skin that is left when you touch 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 moulds. And many of the most common materials found in homes like wood, paper and organic fibers are among the most preferred of mould nutrients. Thus, eliminating mould food from your environment is a virtually impossible task.

Appropriate Temperatures.  Unfortunately, most moulds 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 mould growth and temperatures that are much warmer than humans prefer, like those of the tropics, will grow abundant quantities of mould. Therefore, it is not feasible to control mould growth in our home environment through the control of temperature.

Considerable Moisture.  Most moulds requires the presence of considerable moisture for growth. Obviously, the word “considerable” is key here. The mycologists (fungi scientists) refer to “water activity” when describing the required conditions for mould growth. The various species of mould have different water activity requirements. A material’s “water activity” is equivalent to the relative humidity of the air that would be in equilibrium with the material at that material moisture content. The vast majority of mould species require “water activity” levels that are equivalent to material equilibrium moisture contents corresponding to relative humidities of at least 70%. In fact, the great majority of serious, large mould outbreaks inside buildings occur where porous, cellulose-type materials have literally been kept wet by liquid water or sustained condensation.

Human beings prefer humidities that are below the critical relative humidity for mould growth. Thus, of the four basic requirements for mould growth, moisture availability is by far the easiest mould growth requirement to control in environments that humans like to inhabit. As you will see from the remainder of this guide, and from the vast majority of the literature on mould control, the consensus regarding effective mould control strategies consists of the combination of reducing the availability of moisture and killing and removing active mould growth colonies.

Mould Information – Determining if You Have Mould

Common household moulds have a characteristic “musty” or “earthy” smell, somewhat like the forest floor deep in the woods. Growing colonies of mould can also be visually observed in many cases. Most people are familiar with mouldy bread or mould growth on cheese or other food products that have been kept too long, so the “green fuzzy” characteristic of most mould growth is familiar. And those who have lived in Florida have heard the expression “green shoe syndrome” which refers to the fact that mould is particularly fond of leather products left unused for periods of time in dark humid places.

Although most active mould colonies appear greenish to black (typical of mould growing on bathroom tile grout) in color, the characteristics of mould colonies growing behind vinyl wall covering in buildings takes on very different characteristics. These mould outbreaks typically result in pinkish to yellowish staining of the wall covering. They are quite important because they indicate serious, detrimental moisture accumulations within the gypsum wallboard behind the wall covering that can not be removed by your air conditioning or dehumidification systems. Where these problems appear, they usually require the assistance of a professional equipped with pressure measurement and other diagnostic equipment to determine the source(s) of the moisture causing the problem. Practices That Will Minimize Mould Growth

The following practices will help minimize the growth of moulds inside homes located in hot, humid climates like Florida’s. mould growth on the outside of homes is not covered here and readers are cautioned that these practices may not be applicable in other climates.

  • Air Conditioner Operation: Always set the fan mode switch of your air conditioner thermostat 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 your air conditioner’s evaporator coil during cooling is re-evaporated and blown back into your home before it can drain off the coil and out of your home. This causes the relative humidity in your home to be significantly greater than if the air conditioner thermostat fan mode switch is set to the AUTO position. Even in the “auto” position, some air conditioners run the blower for 1-3 minutes after the compressor shuts off. To maximize dehumidification, it is best to disable this feature. A qualified mechanical contractor should be able to disable this feature so that the blower and compressor turn off simultaneously.  
  • Air Conditioner Selection: If you are building a new home and can choose, then choose an air conditioning system with a variable speed air handler and an operating selection mode for “enhanced moisture removal.” This is a good option for multiple reasons: the units are SEER 14+, they are quiet and they do a better job removing moisture, particularly under part load conditions. They accomplish this by starting the air handler fan at a lower speed during each cycle, which improves moisture removal. The variable speed fan motors are intrinsically more energy efficient– they use as little as 270 W/1000 cfm of air flow as compared with the typical 450 W/1000 cfm. Each of the major manufacturers have them. When used properly, they are ideal for Florida’s climate.  
  • 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. Thus, if a home is properly sized with a 2-ton air conditioner and a 4-ton system is installed, the 2-ton machine would do a much better job removing moisture even though the 4-ton machine had twice the nameplate humidity removal capability (Btu/hr). Remember, the shorter the air conditioner on-cycle, the less chance for effective moisture removal. This fact can be clearly seen in the figure below, which is taken from FSEC test data.  
  • Thermostat Set Point: Set the summertime thermostat to the highest temperature that is comfortable for you. A temperature of 78 F or greater is recommended. Never lower the thermostat temperature in an attempt to control humidity in your home – this will not work. Why? Setting the thermostat temperature lower does two things that are counter to your goal of reducing the moisture content of the materials in your home. First, contrary to what you might intuit, it actually slightly increases the indoor relative humidity in your home! And second, and more important, it decreases the temperature of the materials in your walls, floors and ceilings of your home, thereby significantly increasing the potential for actual moisture condensation on these elements of your home. A side benefit of setting your thermostat at higher temperatures is that it significantly decreases cooling energy costs. In Florida, each one oF increase in thermostat temperature decreases air conditioning cooling energy costs by about 10%. The following table of results from experiments that were conducted by the Florida Solar Energy Center illustrate the relative humidity impacts of both thermostat set point temperature and the position of the fan mode switch.  

Impact of Indoor Set Temperature and Fan Operation Mode on Interior Relative Humidity*


Indoor T (oF)

Avg RH % (Fan= Auto)

Compressor Run Time Fraction

Avg RH% (Fan=On)

















  *  AC operated alternatively for at least one week in each mode.

  • Interior Doors: Interior doors should be kept open when air conditioning unless your 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.  
  • 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 (walls, ceilings, floors, etc.). To get from the outside of the home to the inside, this air often must follow circuitous pathways. For example, the air may enter the wall system high on the exterior where an outdoor light fixture is mounted and exit the wall system low on the indoors where an electrical outlet is located. If the home is air conditioned, the gypsum wallboard will be relatively cold — often colder than the dewpoint temperature of the humid outdoor air that must flow along that gypsum wallboard to that indoor electrical outlet. In Florida, it is not uncommon for summertime outdoor air dewpoint temperatures to be greater than 80 F! When this occurs, the colder gypsum wallboard can act just like that ice tea glass that “sweats” like crazy when you take it outdoors — it can condense the moisture out of the air that is flowing along its back surface on its way to the electrical outlet that is serving as its pathway into the air conditioned home. As illustrated in the figure below, this can result in moisture accumulation within the wallboard, which, in turn, can result in significant mould growth.

The above wall diagrams from detailed computer simulations that model the combined impacts of heat, moisture and air transport illustrate the importance of this air flow phenomena. The wall on the left bounds a space that is pressurized with respect to the outdoors and the one on the right bounds a space that is depressurized. The 2 Pa (Pascal) pressure gradient is very, very small — there are 101,325 Pa in one atmosphere. Clearly, it is the direction of the pressure gradient rather than its magnitude that is critically important here. You very much want your home slightly over pressurized in hot, humid climates so that dry, cool indoor air is pushed out of the home through the walls (figure on left) rather than have hot, humid outdoor air sucked into the home through the walls (figure on right). Fortunately, it is relatively easy to pressurize a home — all that is necessary is that slightly more air be brought into the home than is exhausted. This normally requires a positive mechanical ventilation system.

Things that may cause space depressurization in homes:

Exhaust Fans (bathroom, kitchen, attic, crawlspace, etc.)

Cloths dryers

Supply duct leaks

Insufficient return air pathways due to interior door closure.


Ceiling Fans: Use ceiling fans in the summer — they allow you to be comfortable at higher air conditioning thermostat temperatures. And they will save air conditioning energy costs if you use the most efficient ones (see Gossamer Wind Series – available at (Home Depot stores) and turn them off when no one is in the room.  

Measure the RH in Your Home: Invest in a digital temperature and relative humidity (RH) sensor (about $20) and observe your indoor relative humidities. Two sources for these sensors are Radio Shack and Therma-Stor Products (1-800-533-7533). During the hot summer months, with the air conditioning on, the RH should not exceed 55% during the day on a regular basis. If it does, you probably have problems either with leaks in your duct system or with your air conditioner unit itself – it could be too large, improperly charged or have insufficient air flow across the coil. Consult with a qualified air conditioning expert or mechanical engineer to determine the problem.

The highest relative humilities in your home are likely to occur during mild weather when your air conditioner is not needed during the day. In Florida, the outdoor relative humidity reaches very near 100% on most nights, regardless of daytime temperatures. If your home is open to the outdoors during these periods, the materials in your home will adsorb moisture from this very humid air, again regardless of the temperature. If this moisture is not removed during the following day, the “water activity” of the materials in your home can stay at or above 75% for extended periods and mould is likely to grow on these surfaces. If you have RH levels exceeding 70-75% for extended periods, and find it difficult to control mould growth on surfaces in your home in spring, fall and winter, you may need to invest in some type of dehumidification system and should consult with a qualified mechanical system expert for advice.

  • Vinyl Wall Covering: Impermeable interior surfaces like vinyl wall coverings can result in severe mould problems in hot humid climates such as Florida’s. Moisture coming from outdoors can accumulate within the gypsum wallboard that is behind the vinyl wall covering. This normally occurs as a result of house depressurization where outdoor air is being sucked into the home through the very minute air pathways that exist in all normal wall systems. Where this problem occurs, outbreaks of mould often occur beneath the wall covering on the surface of the gypsum wallboard. This mould growth is normally characterized by pinkish to yellowish “splotches” on the vinyl wall covering. The moisture accumulation also can be severe enough to cause the gypsum wallboard to badly deteriorate and become “mushy.” If you have noticed these symptoms, a building science professional should be consulted. Positive pressurization of your home is one method of minimizing the potential occurrence of this problem.  
  • Return Air Pathways: It is important that there be sufficient air flow pathways for the supply air that is delivered to each room of a home to return to the air conditioner’s air handler unit (the box with the blower fan). Otherwise, the part of the home containing the main return to the air handler unit will be “starved” for air, resulting in depressurization of this space with respect to the outdoors. If this occurs, outdoor air will be drawn through the small pathways that exist in the exterior building envelope. In hot, humid climates like Florida’s, these air flows can result in the accumulation of moisture within the gypsum wallboard, especially if it has vinyl wall covering. This, in turn, can result in the rapid and abundant growth of moulds — remember, the cellulose (paper) on gypsum wallboard makes an excellent, preferred mould food.

If room doors are kept open, there will be sufficient return air pathways. However, if rooms doors are closed, the rule-of-thumb is that there should be about 50 square inches of “free” air transfer area for each 100 cfm (cubic feet per minute) of supply air to the room. In this case, the term “free” means a simple, clear hole in the wall between the room and the remainder of the home. If, for appearance and privacy reasons, this hole is to be covered by grilles on each side of the wall, then the overall return air pathway area needs to be increased by about 40% to account for the air flow resistance of the grilles, or about 70 square inches per 100 cfm of supply air flow.

  • Bathrooms: Most bathrooms, particularly tile in and around showers and tubs is regularly wet. As a result, most bathrooms grow mould 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 mould. 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.)  
  • Whole-House Ventilation Fans — Opened Windows: Avoid the use of these fans when it is humid outdoors, especially if you have noticed mould growth in your home or you are having trouble controlling the relative humidity in your home. In addition, avoid opening windows for long periods when it is humid outside (e.g. during nights and evenings) if you are experiencing mould growth problems in your home.  
  • Air Conditioner Maintenance: Change your filters regularly and use pleated filters. Once a year get your air-conditioners professionally serviced. At that time make sure coils are clean, the condensate drains properly and that the drain pan has no mould.  
  • Exterior Water Management: Redirect water away from the home’s exterior — redirect sprinklers so that they don’t spray on the walls. Do not landscape with hills that direct water flow towards the home. Use gutters. Keep down-spouts free of debris and direct outflow away from the home.  
  • Small Leaks: Even small water leaks will cause mould problems. Rainwater leaks from improperly flashed windows, wall and roof penetrations and plumbing leaks should be promptly repaired. Periodically inspect under sinks and vanities for signs of water leakage. Use you nose and smell for “musty” or “earthy” odors – they usually indicate the presence of mould. Fix all water leaks promptly.  
  • 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. Readers are also encouraged to consult the American Red Cross web site for further information.  
  • Moisture Condensation: Single-pane, metal windows, which are common in Florida, generally condense water on the inside in winter. It is good practice to remove this condensation before it can run off and be absorbed by porous materials like wood casing or gypsum wallboard. Condensation can also occur on other surfaces in homes. If condensation is noticed on interior surfaces in summer, it may indicate a number of problems, including inability to control indoor humidity; air conditioner supply registers aimed directly at interior surfaces; duct leakage problems and pressure imbalances; or all of the above. If you notice indoor surface condensation during summer, you should contact a professional to help diagnose the cause. However, during early spring when the ground is still cool, it is quite possible to experience some condensation on tile floors on slab-on-grade homes that are open to the outdoors. This should not be a regular occurrence, but only something that occurs rarely.  
  • 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 as well. Recalculating stove and kitchen vents provide no removal of stovetop moisture and inferior control of cooking related pollutants compared with venting completely to the outdoors. A major deterrent to the use of kitchen range hoods is noise. Choose an ultra-quiet, inline ventilation fan for your range hood. Kitchen and bath exhaust fans should only be used while cooking or using the bathroom to remove excess moisture generated by these activities.

It is best practice to either have bathroom vent fans interlocked with the light switch so they do not get left on or have them switched by a manual timer that will shut them off after a period of time, or control them by humidistat.  

  • Closets: Fungi 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 all that uncommon to have mould or mildew occur in closets, especially on leather. Leaving the 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 the RH) can reduce these problems.  
  • House Plants: Minimize live house plants, especially if you have any trouble controlling the relative humidity in your home.

Mould Information – Nasty Stuff

Stachybotrys Chartarum, Penicillium and Aspergillus – Toxic, Health threatening moulds, found in homes, businesses and schools near you. These moulds can be found anywhere that dark and dank conditions permit them to grow. When you try to kill them, they take to the air, spreading themselves with no forethought to the damage they can cause. They are just trying to survive. And they’re good at it. Remember the story of the opening of King Tut’s tomb? mould was reportedly thick and pungent. The treasure hunters and laborers took ill after spending long days inside, and many died, but we now know it was NOT because the tomb was “ cursed.” Only in the past decade or less have we begun to understand the potential health risks associated with exposure to mould contamination. Spores can be inhaled, absorbed through the skin or ingested on our food. And, because some people are more susceptible than others, one person may become debilitated by exposure to mould in the home, another person sharing the same environment is essentially unaffected. Infants, the elderly and anyone with immune system deficiencies due to disease, chemotherapy, etc. are particularly susceptible to serious illness following exposure to microbial contamination. Many species of mould and mildew (or the mycotoxins they produce) can cause or aggravate a number of ailments. Common effects from moulds such as stachybotris atra, penecillium, cladosporium and several strains of aspergillius, are asthma, pneumonitis, upper respiratory problems, sinusitis, dry cough, skin rashes, stomach upset, headaches, disorientation and bloody noses. Numerous other species of mould and mildew are also toxic, and many mycotoxins are known carcenogens. Severe exposures can lead to internal bleeding, kidney and liver failure and pulmonary emphysema. Such health risks due to the presence of mould in a dwelling are a serious concern to occupants, and can pose potential liability for owners of rental properties.

Contamination of residential properties by toxic mould and mildew is becoming more and more prevalent. Although mankind has been aware for thousands of years that mould thrives in damp conditions, only recently have we begun to understand how dramatically its presence can impact us. Toxic mould and mildew is not discerning, affecting both old and new buildings. The odor or appearance of mould can signal a variety of problems. The moisture that gives life to fungal growth in older buildings can be either a moisture problem created by tenant’s use, or water intrusion due to leaky components, or both. In new construction, it could also indicate the existence of construction defects ”I Don’t Remember mould Being a Concern Twenty Years Ago” moulds and mildew are everywhere in our environment, and in nature, they perform the very important function of breaking down organic matter. These microbes need very little to survive and thrive: air, moisture (liquid water isn’t necessary, most species propagate with only 40%-60% relative humidity), and food. Fungi are especially fond of building materials like sheetrock and wood, carpets, and enjoy soft goods such as furniture and clothes. Every home offers a smorgasbord for eager spores! There are a number of reasons for the increasing problem of mould and mildew in our homes, not the least of which is the fact that Title 24 to the United States Code of Federal Regulations, relating to energy conservation, brought new construction methods and materials, meaning that buildings don’t “breathe” as freely, trapping moisture vapors inside the building. Most newer homes are built on concrete slabs, which emit moisture for several years as they cure, and because they are porous, moisture from the soil beneath the slab also vaporizes into the living space. Leaky roofs, windows, and plumbing, whether caused by poor construction or lack of timely repairs, often result in colonization of mould and mildew spores. The microbial spores become airborne, spreading inside wall cavities, behind cabinets and wallpaper, and through ventilation systems. When moisture and temperature conditions are favorable, widespread contamination can occur in a surprisingly short time.

Introduction A 1999 Mayo Clinic Study cites moulds as the cause of most of the chronic sinus infections that inflict 37 million Americans each year. Recent studies also link moulds to the soaring asthma rate. moulds have been an under recognized health problem, but that is changing. Health-care professionals now know that moulds can cause allergies, trigger asthma attacks and increase susceptibility to colds and flu. Anyone with a genetic predisposition can become allergic if exposed repeatedly to high enough levels. Last year Dr. David Sherris at the Mayo Clinic performed a study of 210 patients with chronic sinus infections and found that most had allergic fungal sinusitis. The prevailing medical opinion has been that mould accounted for 6 to 7 percent of all chronic sinusitis. The Mayo Clinic study found that it was 93 percent – the exact reverse. Newsweek, 12/4/00

Neither mould nor spores cause illness, other than allergy and/or infections. It is the mycotoxins released when the moulds’ food source (moisture) is severed.

To help comprehend how small mycotoxins are, one common housefly could carry about 7.35 billion attached to its external body hairs. Consequently, IF 50,000 constitute a theoretically lethal dose, a housefly could carry a lethal dose for over 100,000 individuals.

Outdoor spores are not a usual cause of toxicity, (except for allergies and infection), but when growing inside, moulds produce toxins, which are in much higher concentration and can cause illness.

Indoor mould spores indicate mould growth, which indicates mycotoxin production. Currently, we can measure spores, identify spores, but it is difficult to measure mycotoxins. Stachybotrys produces at least 170 known mycotoxins, and probably more that have not been identified.

moulds, a subset of the fungi, are ubiquitous on our planet. Fungi are found in every ecological niche, and are necessary for the recycling of organic building blocks that allow plants and animals to live. Included in the group “fungi” are yeasts, moulds and mildews, as well as large mushrooms, puffballs and bracket fungi that grow on dead trees. Fungi need external organic food sources and water to be able to grow. moulds can grow on cloth, carpets, leather, wood, sheet rock, insulation (and on human foods) when moist conditions exist (Gravesen et al., 1999). Because moulds grow in moist or wet indoor environments, it is possible for people to become exposed to moulds and their products, either by direct contact on surfaces, or through the air, if mould spores, fragments, or mould products are aerosolized. Many moulds reproduce by making spores, which, if they land on a moist food source, can germinate and begin producing a branching network of cells called hyphae. moulds have varying requirements for moisture, food, temperature and other environmental conditions for growth. Indoor spaces that are wet, and have organic materials that mould can use as a food source, can and do support mould growth. mould spores or fragments that become airborne can expose people indoors through inhalation or skin contact.

mould spores are fungal reproductive cells of about the same size as pollen grains. They can occur in various colors and shapes, such as round, spheroid, banana-shaped, or tadpole-shaped. They can occur in enormous quantities, and at all times of the year. mould spores can be found and generated at serious levels indoors, as well as out.

Fungi can invade healthy individuals and can cause a variety of effects. The most common response is allergies (runny nose, sneezing, sinus congestion, and skin rashes). Allergies result from inhaling mould spores. When environmental conditions become conducive, many moulds develop fungal hyphae, small appendages containing spores. These spores are analogous to plant seeds and can be spread by the billions when air currents pass over the hyphae. Even dead fungi are capable of causing allergic symptoms.

mould spores can be airborne, and get indoors through doors, windows or cracks and crevices, or be carried in from the outdoors on shoes and clothing. Building materials that were left outside before use can harbor viable (living) mould spores for many years. Indoor environments are never entirely free of moulds. As a general rule of thumb, in a “healthy” building the concentration of spores and the mix of mould species tend to be similar to outdoor environment levels.

If buildings are air-conditioned, or windows and doors are kept closed in summer, the concentration of spores within should even be lower than outside levels. High moisture (above 70.0% relative humidity) in a building will invariably lead to mould, mildew, or other microbial growth. This growth requires four things: a nutrient source (found in most building materials), proper temperature (usually found indoors), mould spores (ubiquitous in ambient air), and water.

Some moulds also produce toxins (poisons) which are thought to be useful in killing competing moulds in their vicinity. These toxins can also have deleterious effects on humans when ingested, inhaled or in contact with the skin. The fungi that produce toxins are known as toxigenic fungi. Many fungi produce secondary toxic metabolites which can produce adverse health effects (mycotoxicoses) in animals and human. These metabolite are collectively known as mycotoxins. The latest World Health Organization (WHO) publication on mycotoxins, available in 1990, indicated that there are more than 200 mycotoxins produced by a variety of common fungi. Historically, mycotoxins are a problem to farmers and food industries and in Eastern European and third world countries. However, many toxigenic fungi, such as Stachybotry chartarum (also known as Stachybotrys atra) and species of Aspergillus and Penicillium, have been found to infest buildings with known indoor air and building-related problems. Many indoor air quality related problems have been traced to the growth of fungus in buildings. Almost without exception, these buildings have usually had chronic water or moisture problems.

moulds can have an impact on human health, depending on the nature of the species involved, the metabolic products being produced by these species, the amount and duration of individual’s exposure to mould parts or products, and the specific susceptibility of those exposed. Health effects generally fall into four categories Allergy, Infection, Irritation, Toxicity

Toxicity moulds can produce other secondary metabolites such as antibiotics and mycotoxins. Antibiotics are isolated from mould (and some bacterial) cultures and some of their bacteriotoxic or bacteriostatic properties are exploited medicinally to combat infections.

Mycotoxins are also products of secondary metabolism of moulds. They are not essential to maintaining the life of the mould cell in a primary way (at least in a friendly world), such as obtaining energy or synthesizing structural components, informational molecules or enzymes. They are products whose function seems to be to give moulds a competitive advantage over other mould species and bacteria. Mycotoxins are nearly all cytotoxic, disrupting various cellular structures such as membranes, and interfering with vital cellular processes such as protein, RNA and DNA synthesis. Of course they are also toxic to the cells of higher plants and animals, including humans. Mycotoxins vary in specificity and potency for their target cells, cell structures or cell processes by species and strain of the mould that produces them. Higher organisms are not specifically targeted by mycotoxins, but seem to be caught in the crossfire of the biochemical warfare among mould species and moulds and bacteria vying for the same ecological niche.

Mycotoxin Effects – The class of small fungal secondary metabolites which has been given the name “mycotoxins” is definitely known to include many compounds which are highly toxic to vertebrates (such as humans). Most of the well characterized toxic effects are from animal feeding situations, either natural mycotoxicosis outbreaks caused by contaminated animal feed, or laboratory experiments based on feeding (or connected artificial experimental situations such as parenteral injection of purified toxins into experimental animals). Ingestion of mycotoxin-contaminated foods by humans results in similar symptoms. Toxic effects have also been found in laboratory experiments in which animals are exposed to mycotoxins via the respiratory tract. In cases involving humans and airborne exposure, the most suggestive of a direct mycotoxin effect are those in which heavily mould-exposed workers develop severe symptoms reminiscent of animal mycotoxicoses or contaminated-food mycotoxicoses Organic Compound’s & Mycotoxins :

You can find a lot of information on mould, but trying to understand it may be difficult to those who didn’t take biology and chemistry. Even after stumbling through the pronunciation of these words, not everyone can comprehend what was meant by the statement. “Satratoxin, a low-molecular weight non-volatile organically derived agent, belongs to the macrocyclic trichothecene class of mycotoxins generated from fungal microorganisms.”

As an aid to the homeowner, this overview is intended to explain a few bad products of mould in a less scientific manner. It will focus on those types of mould that have been considered as problematic to the “indoor mould issue” and does not address other fungal organisms which may behave differently. Analogies presented are not intended to be scientifically accurate, but rather to illustrate complex behaviors in more simple terms.

The people who study mould (mycologists) have identified and described over 100,000 species and many believe that this is only a partial listing (estimates of 1.5 million species have been suggested). Try jotting down the names of the first 100,000 people you know then describe each person’s behavior in a specific setting. You will begin to understand the complexities of the problem facing these mould professionals.

Most people have associated mould with allergies and these reactions are certainly prevalent with most all species found indoors. In addition to causing an allergic response, moulds can be irritating, infectious and even toxic to humans. Understanding the general behavior of mould provides insight into the adverse components produced by mould.

The Organism

Fungi can be considered nature’s garbage disposal. Without them, the term “biodegradable” would not be so significant to our planet and we would have mountains of leaves, dead trees, and other organic materials sitting around…all deposited since the beginning of time. This, in simple terms, is the ‘why’ of mould.

For the moment, think of mould as a weed. This weed has a root system, a vegetative stalk, and a seed pod. For mould, the root system is made up of hyphae (high-fee). As hyphae grows into a mass during the vegetative state, it becomes a mycelium (my-sill-ee-um). The spores, designed for reproduction, are similar to seeds.

Like a weed, mould needs food and water to survive (yes, both need more than that, however, we are simplifying things here). For mould, the food of preference is organic matter (things that once were living). Indoors, those things are wood, paper, organic dust and dirt, leather, skin flakes, body oils, etc.

When mould spores that are floating around in the air land on a food source, they sit there patiently waiting for water. If the item they land on should contain sufficient moisture, or water comes from another source (leaks, etc.), the spore germinates and hyphae grows. The hyphae branch out, secrete enzymes to breakdown the food, form the mycelium, and absorb nutrients to grow. As long as the food and water hold out, colonies will continue to grow. Note that individual hyphae and spores are very, very small and few can see them without a microscope. When you see visible mould, you are generally seeing that mass of mycelium.

Hyphae can intertwine into the fibers of the substrate, penetrating the pores. As it consumes the substrate, it can also create it’s own route by dissolving pathways into the material. This is one of the reasons it is so difficult to kill and/or clean up mould on organic substrates. If you remove the surface growth, those bits of hyphae within the substrate are ready for re-growth upon the return of moisture.

As the organism matures, it develops spores intended for reproduction. Spores vary in size, shape, weight and methods of distribution. Some are light and buoyant so they float easily through the air. Others are wet and sticky and may cling to insects, rodents, etc. as a mode of travel.

As mould “consumes” it’s food, the chemical reactions of enzymes, substrates and mould growth produce carbon dioxide, water, and volatile organic compounds (VOC’s). Because these items are a result of actions essential to the growth of the organism, they are classified as primary metabolites.

For mould, many types of VOC’s are produced and typically include aldehydes, alcohols, keytones, and hydrocarbons. They have complex structures and names like “2-methyl-1-propanol”, so if you are going to dig deeper into VOC’s, get ready for chemistry class.

They are called volatile in that they evaporate easily at room temperature and pressure. Fortunately, this volatility aids in dilution with fresh air to minimize concentrated build-up of these chemicals. Testing for VOC’s is often accomplished by using vacuum cylinders to obtain samples of the air with laboratory analysis obtained from sophisticated test instruments (gas chromatograph/mass spectrometer).

When you smell a “musty-mouldy” odor, it’s generally the VOC’s you are noticing. VOC’s are often considered irritants to mucus membranes, however, are also capable of both short-term and long-term adverse health effects. If you do smell these odors, it’s a sure sign the mould is consuming and growing and you need to take action. (Note that VOC’s may also be derived from non-mould sources including natural materials used in cleaning agents.)


Many moulds are capable of producing compounds called mycotoxins which are toxic to other organisms, including people. Mycologists believe these toxins are produced as protection against competing organisms and therefore, humans are simply caught in the cross-fire of this fight for survival.

Since these toxins are not essential for growth, they are classified as secondary metabolites. Toxic secondary metabolites require extra work on the part of the organism so production does not occur at all times, or, with all types of mould.

Scientists have identified over 400 mycotoxins and unlike VOC’s, these compounds are usually non-volatile (don’t evaporate easily at room temperature and pressure). One strain of mould may produce multiple toxins and one type of toxin may be produced by multiple strains of mould. Research has indicated that the type of substrate (nutrients), the growing conditions, together with the species of mould, will impact which toxins are created.

Some of these toxic substances are considered extremely hazardous to people, unfortunately, quantified human dose-response data is limited. Lab and field studies have shown these compounds to produce severe toxic effects in both animals and humans and therefore, the general recommendation is to minimize exposure to potentially toxigenic mould. Symptoms from toxic exposure range from flu-like symptoms, skin rashes and lesions, bleeding, fatigue, difficulty breathing, depression, etc. to longer-term nerve and organ problems, altered immunity, and cancer.

Not all secondary metabolites are considered bad for people…the antibiotics such as penicillin have beneficial use. However, from the mycological standpoint, antibiotics are considered mycotoxins since they too are generated by mould to ward off microorganisms (i.e. competing bacteria).

When the organism is producing toxins, the toxins are known to be present in the cell wall of spores and hyphae. It’s relatively easy to test for spores and hyphae, however, testing these components to see if they contain toxins is significantly more complex. Whereas a single spore can be viewed under a microscope, identifying what compounds are contained in the cell wall is difficult.

In order to identify these toxic compounds, laboratories must have a sufficient quantity of toxin-containing spores and carefully process them through sophisticated and expensive equipment that is capable of isolating chemicals down to billionths of an gram (remember, mould spores are microscopic so what is contained within it’s cell wall is extremely small). This testing is made even more difficult since there are a few hundred toxins to analyze and the behavior of mould is such that a toxin-producing mould in the field doesn’t necessarily produce the same type and quantity of toxins in the lab.

Generally speaking, identifying a mould type that is known to be capable of producing toxins is sufficient information to warrant precautions and avoid exposure without submitting for toxic analysis. However, if trying to confirm specific adverse health effects, obtaining an analysis of both VOC’s and toxins can be beneficial but often expensive.

Common Symptoms

As another example, classic stachybotryotoxicosis, described mostly from agricultural workers who handled or disturbed large quantities of material (usually hay or straw) contaminated by Stachybotrys chartarum, was characterized by

(1) “Cough, rhinitis, burning sensation in the mouth, (throat) and nasal passages, and cutaneous irritation at (points) of toxin contact”

(2). Nosebleeds were also common, and tracheal bleeding was occasionally reported. Whether such mycotoxin effects explain the symptoms seen in common building exposures has been disputed. It has been pointed out that, although the mycotoxins are often associated with disseminating fungal conidia, the quantities present may not be sufficient to explain the effects observed

(3), at least not in terms of classic toxicosis. A number of mycotoxins or conidia of mycotoxigenic fungi, however, have also been shown to have effects such as activation of pulmonary alveolar macrophages (PAMs), DNA fragmentation in PAMs, inhibition of the oxidative burst killing mechanism in PAMs, and slowing of respiratory ciliary beat

(e.g., 4). Such interactions with immune mechanisms may explain some symptoms not explained by toxicosis. Careful study of occupants of contaminated buildings suggests an association between inhalation of toxigenic fungi and nonspecific respiratory symptoms

(5) mouldy Odors are released from actively growing fungi may also pose a health risk. Not all moulds produce mycotoxins, but numerous species do (including some found indoors in contaminated buildings). Toxigenic moulds vary in their mycotoxin production depending on the substrate on which they grow (Jarvis, 1990). The spores, with which the toxins are primarily associated, are cast off in blooms that vary with the mould’s diurnal, seasonal and life cycle stage (Burge, 1990; Yang, 1995). The presence of competitive organisms may play a role, as some moulds grown in monoculture in the laboratory lose their toxic potency (Jarvis, 1995). Until relatively recently, mould poisons were regarded with concern primarily as contaminants in foods. More recently concern has arisen over exposure to multiple mycotoxins from a mixture of mould spores growing in wet indoor environments. Health effects from exposures to such mixtures can differ from those related to single mycotoxins in controlled laboratory exposures. Indoor exposures to toxigenic moulds resemble field exposures of animals more closely than they do controlled experimental laboratory exposures. Animals in controlled laboratory exposures are healthy, of the same age, raised under optimum conditions, and have only the challenge of known doses of a single toxic agent via a single exposure route. In contrast, animals in field exposures are of mixed ages, and states of health, may be living in less than optimum environmental and nutritional conditions, and are exposed to a mixture of toxic agents by multiple exposure routes. Exposures to individual toxins maybe much lower than those required to elicit an adverse reaction in a small controlled exposure group of ten animals per dose group. The effects from exposure may therefore not fit neatly into the description given for any single toxin, or the effects from a particular species, of mould.

Few toxicological experiments involving mycotoxins have been performed using inhalation, the most probable route for indoor exposures. Defenses of there respiratory system differ from those for ingestion (the route for most mycotoxin experiments). Experimental evidence suggests the respiratory route to produce more severe responses than the digestive route (Cresia et al.,1987). Effects from low level or chronic low level exposures, or ingestion exposures to mixtures of mycotoxins, have generally not been studied, and are unknown. Effects from high level, acute sub-acute and sub-chronic ingestion exposures to single mycotoxins have been studied for many of the mycotoxins isolated. Other mycotoxins have only information on cytotoxicity or in vitro effects.

Effects of multiple exposures to mixtures of mycotoxins in air, plus other toxic air pollutants present in all air breathed indoors, are not known. Effects of other biologically active molecules, having allergic or irritant effects, concomitantly acting with mycotoxins, are not known.

Measurement of mould spores and fragments varies, depending on instrumentation and methodology used. Comparison of results from different investigators is rarely, if ever, possible with current state of the art. While many mycotoxins can be measured in environmental samples, it is not yet possible to measure mycotoxins in human or animal tissues. For this reason exposure measurements rely on circumstantial evidence such as presence of contamination in the patient’s environment, detection of spores in air, combined with symptomology in keeping with known experiment allesions caused by mycotoxins, to establish an association with illness.

Response of individuals exposed indoors to complex aerosols varies depending on their age, gender, state of health, and genetic make-up, as well as degree of exposure. Microbial contamination in buildings can vary greatly, depending on location of growing organisms, and exposure pathways. Presence in a building alone does not constitute exposure.

Investigations of patients’ environments generally occur after patients have become ill, and do not necessarily reflect the exposure conditions that occurred during development of the illness. All cases of inhalation exposure to toxic agents suffer from this deficit. However exposures to chemicals not generated biologically can sometimes be re-created, unlike those with active microbial growth. Indoor environments are dynamic eco systems that change over time as moisture, temperature, food sources and the presence of other growing microorganisms change. Toxin production particularly changes with age of cultures, stage of sporulation, availability of nutrients, moisture, and the presence of competing organisms. After-the-fact measurements of environmental conditions will always reflect only an estimate of exposure conditions at the time of onset of illness. However, presence of toxigenic organisms, and their toxic products, are indicators of putative exposure, which together with knowledge of lesions and effects produced by toxins found, can establish association.

Field exposures of animals to moulds (in contrast to controlled laboratory exposures) show effects on the immune system as the lowest observed adverse effect. Such immune effects are manifested in animals as increased susceptibility to infectious diseases. It is important to note that almost all mycotoxins have an immune suppressive effect, although the exact target within the immune system may differ. Many are also cytotoxic, so that they have route of entry effects that may be damaging to the gut, the skin or the lung. Such cytotoxicity may affect the physical defense mechanisms of their respiratory tract, decreasing the ability of the airways to clear particulate contaminants (including bacteria or viruses), or damage alveolarmacrophages, thus preventing clearance of contaminants from the deeper lung. The combined result of these activities is to increase the susceptibility of the exposed person to infectious disease, and to reduce his defense against other contaminants. They may also increase susceptibility to cancer (Jakabet al., 1994).

Because indoor samples are usually comprised of a mixture of moulds and their spores, it has been suggested that a general test for cytotoxicity be applied to a total indoor sample to assess the potential for hazard as a rough assessment (Gareis, 1995).

Animal experiments in which rats and mice were exposed intranasally and intratracheally to toxic strains of S. chartarum, demonstrated acute pulmonary hemorrhage (Nikkulin et al. 1996). A number of case studies have been more recently published. One involving an infant with pulmonary hemorrhage in Kansas, reported significantly elevated spore counts of Aspergillus/Penicillium in the patient’s bedroom and in the attic of the home. Stachybotrys spores were also found in the air of the bedroom, and the source of the spores tested highly toxigenic. (Flappan et al., 1999). In another case study in Houston, Stachybotrys was isolated from bronchopulmonary lavage fluid of a child with pulmonary hemorrhage. (Elidemir et al., 1999), as well as recovered from his water damaged-home. The patient recovered upon removal and stayed well after return to a cleaned home. Another case study reported pulmonary hemorrhage in an infant during induction of general anesthesia. The infant was found to have been exposed to S. chartarum prior to the anesthetic procedure (Tripi et al., 2000). Still another case describes pulmonary hemorrhage in an infant whose home contained toxigenic species of Penicillium and Trichoderma (a mould producing trichothecene poisons similar to the ones produced by S. chartarum) as well as tobacco smoke (Novotny and Dixit, 2000) Toxicologically, S. chartarum can produce extremely potent trichothecene poisons, as evidenced by one-time lethal doses in mice (LD50) as low as 1.0 to 7.0 mg/kg, depending on the toxin and the exposure route. Depression of immune response, and hemorrhage in target organs are characteristic for animals exposed experimentally and in field exposures (Ueno, 1980; Jakab etal., 1994).

While there are insufficient studies to establish cause and effect relationships between Stachybotrys exposure indoors and illness, including acute pulmonary bleeding in infants, toxic endpoints and potency for this mould are well described. What is less clear, and has been difficult to establish, is whether exposures indoors are of sufficient magnitude to elicit illness resulting from toxic exposure. The toxic mould environmental risk may be one of the next major real estate “due diligence” concerns, especially in property development areas where major flooding has occurred. The problem is that this not only includes known residential and commercial flood areas incidents, but also numerous minor water releases due to plumbing failures, conductive condensation, house water leaks and accidents. The toxic mould concern could also be a problem where fires occurred at residential properties.

The second major concern is that one might not be able to permanently eliminate the entire toxic mould from the structure. There also remains a great propensity for future reoccurrence. The health risk/hazard could be back again. Therefore, we must recommend that great care be exercised to remove and dispose of all products, which have been contaminated by the toxic mould contaminated. The Department of Health Administrations in many states supports this recommendation.

The third concern is that States’ Health Departments will consider ambiguous and genetic disposition as a response to the publics’ inquiries. There will be some people, especially children, that will exhibit more adverse reactions, including death, lung tissue damage, and memory loss, than other persons exposed to the toxic mould. This may depend on the chemical sensitivity, genetic disposition, predisposing health history (such as allergies, asthma, smoking, etc.). For some, the exposure to the toxic mould spores may just be a “health risk” and to others, it may be a real “health hazard” (potential life-threatening and loss of “quality of life”.) Whether a potential liability concern is a risk or hazard will be paramount in defining the critical level of due diligence and disclosure response by responsible parties. There are already several major lawsuits concerning toxic mould exposure in residential and commercial buildings throughout the United States. Currently, most health organizations consider exposure to Stachybotrys mould as a health hazard.

Also, keep in mind that most responses leading to testing, investigations, and abatement of the Stachybotrys toxic mould are due directly to occupant complaints or documented detrimental health effects. Stachybotrys mould may evolve to a point where it is regarded with the same cautions, response and liability concerns as those attributed to lead-base paint and asbestos. Health hazards and risks associated with concern to exposure to Stachybotrys are currently considered as short-term effects. Exposure to radon gas in houses is considered a long-term health risk and is not considered a short-term hazard. 

A Creeping Catastrophe

In February 2000, a Texas grand jury found reason to continue a criminal investigation of child endangerment charges against an insurance company for its handling of a water damage claim. This investigation was prompted by a criminal complaint filed by the policyholder and follows the filing of a $100 million lawsuit in 1999 against the same insurance company for its handling of the claim. The policyholders say that the insurance company did not act properly or in a timely manner following the water damage claim. The allegation is that the house is now uninhabitable.

The family claims that, following the water damage, and while they were still living in the house during repairs, they were coughing up blood. The husband, the family claims, is now suffering from a cognitive dysfunction, among other injuries.

The problem? mould. Stachybotrys chartarum (a.k.a. atra) to be specific. The mould developed following a water damage loss in 1998. The policyholders allege that neither the insurance company nor the company’s expert informed the family that the home contained the deadly mould until their health was irreversibly damaged.

Is the Texas case merely an extreme example? Or is it a harbinger of things to come?

Many lawsuits have been filed and are being filed around the country involving the improper handling of covered water damage losses that have resulted in mould growth so extensive and severe as to present potentially serious – and in too many cases, actual – health hazards, not only to the occupants of the building involved but possibly to anyone who unwittingly enters the structure. Furthermore, mould growth can cause damage to building materials, such as paper and wood products. mould contamination and growth may also pose a disclosure issue during a real estate transaction.

According to the Insurance Information Network of California and the Western Insurance Information Service, both sponsored by insurance companies, water damage from frozen and broken water pipes ranks second, behind hurricanes, in terms of the number of homes damaged and the amount of claim costs in the U.S. Damage from water is the most prevalent, yet least recognized, catastrophe. In addition to broken and frozen water pipes, we have to include losses from flood, rain, leaks and surface water, as well as water damage from putting out fires.

Some of these losses are covered, some are not. If the water damage is the result of a covered loss, the resultant damage, mould (including fungi, mildew, etc.), is probably also covered and must be considered in preparing the scope of damages and costs of repair.

The consensus of opinion from the EPA, FEMA, the Centers for Disease Control (CDC), mycologists and microbiologists is that mould may start to grow and spread within 24 to 48 hours in structures damaged by water. mould can grow exponentially, given the right conditions of temperature, moisture and food sources, such as sheetrock.

Mould Information – Know your enemy

 Fungi are a group of organisms with nuclei and rigid cell walls, but without chlorophyll. They may be unicellular or in multicellular filaments. The filaments are called hyphae. A fungus may produce a system of branching filaments, called the mycelium. The filamentous fungi are sometimes called moulds. Unicellular fungi are often called yeasts. Some fungi may produce both yeast and mycelial mould phases. Mildew, in layperson’s terms, describes the staining, and likely the degradation of the materials, caused by fungi or moulds. Mildew is also used by plant pathologists to identify plant diseases, such as “powdery mildew,” caused by fungi. or moulds. Mildew is also used by plant pathologists to identify plant diseases, such as “powdery mildew,” caused by fungi.

Mould, mildew and fungi are hardly new problems. In the book of Leviticus, chapters 13 and 14, there is reference to a plague, also called mildew in some translations. The description seems to fit that of a toxic mould. In Leviticus, the solution was to try cleaning: “Watch the plague and if the plague spreads, the unclean item or property must be removed and destroyed.”

Stachybotrys chartarum was first identified and described by a scientist from wallpaper collected in a home in Prague in 1837. The toxic effects of Stachybotryshave been reported as early as the 1920s.

Reports and surveys on mould in homes have been published since at least the late 1970s. In 1986, the injurious effects of trichothecenes – a mycotoxin produced by Stachybotrys chartarum and a few other moulds – were reported from a study of a family in Chicago. That report, by W.A. Croft, said that Stachybotryscould be commonly found in homes with water damage, could grow undetected behind walls and could grow profusely on sheetrock.

In 1993, the New York City Department of Health’s Bureau of Environmental & Occupational Disease Epidemiology convened a panel of experts to study a growing and noted problem. Their report, “Guidelines on Assessment and Remediation of Stachybotrys Atra in Indoor Environments,” was issued in 1994. An updated report, Guidelines on Assessment and Remediation of Fungi in Indoor Environments, was issued in April 2000. The scope of the report was expanded to include all mould or fungi.

These guidelines serve as the accepted standard on how to deal with mould. The initial 1994 report focused on Stachybotrys, but was revised in 2000 to include all mould (fungi). The authors highly recommend that concerned readers download and print out copies for reference, which run about 17 printed pages. (For more information, contact he N.Y.C. Department of Health at (212) 788-4290.)

Mould Information – Mould & medical problems 

A wide variety of symptoms have been attributed to the toxic effects of different moulds. The medical problems may be caused by toxic gases produced by the moulds or by reactions to the mould particles themselves. Many allergies are also attributable to mould and fungi.

Commonly reported symptoms include runny noses, eye irritation, congestion, and aggravation of asthma, headaches, dizziness and fatigue. More severe symptoms may include reports of profusely bloody runny noses, the coughing up of blood, severe headaches, fibrous growth in the lungs and – at least in one reported instance – cognitive dysfunction and loss of memory.

In the previously described water damage and mould claim in Texas, a mould expert in the case underestimated the danger involved. The expert found himself throwing up for hours after spending just 30 minutes in the house. He has a severe hearing loss in one ear from his exposure to the mould.

In 1993 and 1994, a doctor from the Cleveland area attributed 37 cases of pulmonary hemorrhage and hemosiderosis in young infants to Stachybotrys. Twelve of the infants died. A recent CDC report questions the scientific validity of the doctor’s conclusions and the causal linkage of the infant deaths to the toxic effects of Stachybotrys. However, the CDC does recognize that mouldy homes are unhealthy for human occupancy. Other reports claim to confirm the linkage of Stachybotrysto instances of infant deaths in other locations.

Some of the most extreme cases of mould-related health problems, the so-called “yellow rain” attacks in Southeast Asia during the late 1970s, and the Iraqi attacks on some Kurd villages in the 1980s and 1990s have been attributed to use of mycotoxins produced by moulds.

The conclusion to be reached from all of these dramatic cases is that moulds are potentially dangerous and cannot be ignored. All moulds should be removed. If the mould is attributable to a covered loss, it is the responsibility of the adjuster to include removal of the mould as part of the loss.

Mould Information – Immediate response required

While all claims should be responded to and handled promptly, timeliness on covered water damage claims is especially critical. A prompt response and an immediate commencement of cleanup and drying is essential in reducing or eliminating further damage, particularly by mould. The sooner the water is removed and the property properly dried out, the less property damage there will be and any related claim will also be correspondingly minimized. Water damage that is not addressed within 24 to 72 hours may result in the growth and spreading of mould which could be toxic. A visual inspection is the most important step in identifying possible mould contamination. The inspection should include any areas damaged by water, e.g., behind cabinets, in attics, under carpets, inside wall cavities and any area with porous material or soft goods exposed to high humidity (over 60 per cent) or water for a period in excess of 72 hours.

The general rule of thumb is very simple: If you can see mould or smell mould, you have to remove it. Once you find and start removing the mould-damaged or contaminated materials, such as sheetrock, you should keep on removing the material until you find no more mould, either on the face of the sheetrock or on the back side of the sheetrock next to the studs. If the studs have mould contamination, you must consider the edge of the stud on which the other or exterior wall is attached.

Since the N.Y.C. Department of Health’s panel of experts concluded that it was not possible to determine safe or unsafe levels of exposure for people with varying degrees of susceptibility, the guidelines essentially call for the removal of all visible mould.

The New York City guidelines state that in looking for mould following water damage, bulk sampling or air monitoring is not required. Remediation of all visibly identified mould contamination should proceed without further evaluation. However, if mould is not visible but is suspected because of circumstances such as water damage and unexplained illness, it may become necessary to test in order to rule out mould or to verify its presence. Porous materials, such as ceiling tiles, insulation and wallboards, with more than a small area of mould contamination should be removed and discarded. A small isolated area is defined as 10 square feet or less. A small area may be cleaned safely if done properly, without problems, and a check reveals no more mould.

Removal of the mould-contaminated material is only the first step. A certified mould remediation specialist should then remediate or decontaminate the structure and personal property involved.

Depending on such variables as the length of time from the initial water damage, the amount of water in the structure, the cleanliness of the water and the type of property involved, it may be necessary to remove carpets, pads and any other wet items (especially clothing and other soft goods) from the premises for proper drying, cleaning and treatment. Damp or wet carpets, pads or other items may provide a medium for potentially dangerous mould growth.

Flooding of property, pipe breaks in ceilings or walls, or standing water necessitates removing sheetrock that has been water-damaged, up to at least a foot or more above the high-water mark. Removal of at least some sheetrock may also be necessary to allow the wall cavities to drain and dry properly. Wet insulation, in the ceiling or walls, must be removed and replaced. Wet or damp insulation, especially in dark places like wall cavities is a breeding ground for mould. The insulation value is also reduced.

Prompt response and appropriate action is necessary to minimize damage in a water loss. A quick response will also allow the adjuster to determine if the mould is pre-existing or a result of the water damage. If the adjuster can inspect the loss within 24 or 48 hours of the initial damage, it is likely that any visible or detected mould may be the result of a pre-existing water problem, possibly a long-term leak. However, if the loss is not inspected or properly dried within 72 to 96 hours, it may be more difficult to determine if the mould was a pre-existing problem or a result of the covered loss, and thus also covered. The longer the delay in inspecting the loss, the more difficult it becomes to prove the mould was not caused by the covered loss.