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Farmer’s Lung

If you are complaining about mould in your house, try living inside a mouldy barn all day. For generations those who grow our food supply have had to put up with high levels of mould spores in their work place. And there is very little our farm workers can do to alleviate the sometimes high levels of toxic spores that can perpetuate under hot humid conditions. Farmers Lung is a serious noninfectious respiratory ailment which can seriously harm a farmers lungs forcing some of them out of work.




Did You Know?

New homes are more susceptible to mould problems than older homes because of advanced insulation methods. Keeping the cold out in the winter while maintaining cooling temperatures in the summer can cause excessive moisture buildup inside the home.



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Frequently Asked Questions   If you don't find your answer, just contact us!.

Is it MOULD or MOLD? The American way to spell this word is Mold. The British on the other hand spell it Mould. In Canada either way of spelling this word seems acceptable but it is mostly referred to as mould.


The Facts About Mould: General Information The Facts About Mould: Health Risks The Facts About Mould: Removal and Remediation The Facts About Mould: Further Information

The Facts About Mould: General Information


What Is Mould?

Moulds are forms of fungi found all year round both indoors and outdoors. Outdoors, moulds live in the soil, on plants, and on dead or decaying matter. Another common term for mould is mildew. Mould growth is encouraged by warm and humid conditions, although it can grow during cold weather. There are thousands of species of mould and they can be any color. Many times, mould can be detected by a musty odor. Most fungi, including moulds, produce microscopic cells called spore that spread easily through the air. Live spores act like seeds, forming new mould growths (colonies) with the right conditions. All of us are exposed to fungal spores daily in the air we breathe.

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What Causes Mould To Develop?

Mould requires nutrients, water, oxygen and favorable temperatures to grow. Nutrients for mould are present in dead organic material such as wood, paper or fabrics; mould can also derive nutrients from some synthetic products such as paints and adhesives. Mould requires moisture, although some mould species can obtain that moisture from moist air when the relative humidity is above 70 per cent. Many moulds thrive at normal indoor temperatures; few if any moulds are able to grow below 40 F or above 100 F. Outside this range moulds may remain dormant or inactive; they may begin to grow again when the temperature is more favorable. Temperatures well above 100 F will kill mould and mould spores, but the exact temperature required to kill specific species is not well established.

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How Does Mould Get Into A Building?

Moulds are decomposers of organic material such as wood, plants and animals. Mould and mould spores are found in high concentrations wherever there is dead matter such as a pile of leaves, manure or compost. Mould spores enter buildings through the air or on people, animals and objects that are brought into the building. Spores are small bundles of genetic material and chemicals (similar to seeds) that moulds make under certain conditions.

Most, if not all, of the mould found indoors comes from outdoor sources. It needs moisture to grow and becomes a problem only where there is water damage, high humidity, or dampness. Common sources of indoor moisture that cause mould problems include flooding, roof and plumbing leaks, damp basements or crawl spaces, or any moisture condensation on cold surfaces. Bathroom showers and steam from cooking may also create problems if not well ventilated.

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Does Tighter Building Construction Promote Mould Development?

Tighter building construction does not by itself promote mould growth, but tight construction combined with some poor choices in design, building materials or operations can increase the probability of mould growth. What do we mean? The tighter the building construction the less air exchange there is between the inside air and the outside air. Whatever gets into the inside air stays there longer than it would in a house with loose construction. Moisture that gets into the air from activities such as cooking, bathing and even breathing will remain in a tight house longer than it would in a loose house. That's why exhaust fans should be installed in bathrooms and kitchens and vented to the outside. Clothes dryers should also be vented to the outside.

Tight construction permits control of the air exchange between the inside and the outside and can prevent the deposition of moisture in walls and roofs. Controlling moisture, including indoor relative humidity is the key to preventing mould growth. Tight building construction when combined with source control of moisture (exhaust fans) and controlled ventilation (intentional introduction of outside air) reduces the probability of mould growth in a building. Controlled ventilation can be provided by a duct that brings outside air to the return side of the air handler of a forced air system. A timing device or fan cycler can be programmed to have the air handler turn on for a specified number of minutes each hour even when there is no call for heating or cooling. In cold climates, controlled ventilation is frequently provided by a heat recovery ventilator (HRV).

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Do New Building Materials (E.G. Drywall Or Paper Faced Gypsum Board) Promote Mould Growth?

Mould needs water, a nutrient source, oxygen and favorable temperature to grow. Many species of mould love paper faced gypsum board. Why? Making paper involves the mechanical and chemical processing of wood. Paper is largely pre-digested so it is easy for mould to get nutrients from the paper. However, unless there is enough moisture present, mould can't grow on the paper. If paper faced gypsum board is kept dry, it can be used and still not have mould. This material is kept dry by controlling the interior relative humidity, keeping rain from entering roofs and walls, and NOT using paper faced gypsum in areas that are likely to get wet. This means no paper faced gypsum board in shower and tub areas. Cement board, mortar or non-paper faced gypsum can safely be used in these damp areas because these products do not contain nutrients to support mould growth.

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How Can I Prevent Mould Growth?

Controlling excess moisture is the key to preventing and stop ping indoor mould growth. Keeping susceptible areas in the home clean and dry is very important. Ventilate or use exhaust fans (vented to the outdoors) to remove moisture where it accumulates, particularly in bathrooms, kitchens, and laundry areas. Clothes dryers should be vented to the outside. Repair water leaks promptly, and either dry out and clean or replace water-damaged materials. Materials that stay wet for more than 48 hours are likely to produce mould growth. Lowering humidity indoors helps prevent condensation problems. To lower humidity during humid weather, use air conditioners and dehumidifiers. Proper exterior wall insulation helps prevent condensation from forming inside during cold weather.

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What Is Black Mould?

The news media often refer to black mould or toxic black mould. It is usually associated with Stachybotrys chartarum, a type of greenish-black mould commonly associated with heavy water damage. Not all moulds that appear to be black are Stachybotrys. The known health effects from exposure to Stachybotrys are similar to other common moulds, but have been inconclusively associated with more severe health effects in some people.

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The Facts About Mould: Health Risks


Why Are We Concerned About Mould?

Small amounts of mould growth in workplaces or homes (such as mildew on a shower curtain) are not a major concern. However, no mould should be allowed to grow and multiply indoors. Large quantities of mould growth may cause nuisance odors and health problems for some people. In addition, mould can damage building materials, finishes, and furnishings and, in some cases, cause structural damage to wood.

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Are There Harmful And Non-Harmful Moulds?

There are only a few moulds that can cause infection in healthy humans. Some moulds cause infections only in people with compromised immune systems. The biggest health problem from exposure to mould is allergy and asthma in susceptible people. There are more than 100,000 types of mould. Good information has been developed for only a small number of these moulds at least in terms of their effects on human health. Most people tolerate exposure to moderate levels of many different moulds without any apparent adverse health effects.

Some moulds produce powerful chemicals called Mycotoxins that can produce illness in animals and people. Scientific knowledge about the health effects of these toxins on humans is quite limited.

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Does Mould Affect Everyone The Same Way?

No. Some individuals have a genetic makeup that puts them at risk for developing allergies to mould. People, who have an allergy to mould, especially if they also have asthma, can become ill from exposure to a small amount of mould. Individuals also seem to be quite different in their response to exposure to the toxic chemicals that some moulds release. These differences between individuals contribute to the difficult question of determining safe exposure limits for mould.

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How Much Mould Exposure Is Harmful?

No one knows the answer to this question for several reasons. Individuals are very different with respect to the amount of mould exposure they can tolerate. Children under the age of one year may be more susceptible to the effects of some moulds than older individuals. Measuring or estimating exposure levels is very difficult. Exposure means the amount of mould (microscopic spores and mould fragments) that gets into a person usually by breathing, but also by eating or absorption through the skin. For example, a building may have a lot of mould in the walls but very little of that mould is getting into the air stream. In that case the people working or living in that building would have little mould exposure.

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Can Mould Exposure Cause Brain Damage Or Death?

Although some experts claim that individuals have brain damage or have died because of exposure to mould and especially mould toxins, there is no good science at this time to support these claims. Consequently it is prudent to minimize ones exposure to really mouldy environments. By really mouldy we mean where there are large visible areas of mould (more than a few square feet) or the building has a musty odor because of hidden mould growth. There are many epidemiological studies showing that people who live in houses with dampness have many more health problems, especially respiratory, than do people who live in dry houses. This association does not prove that it is the mould that is responsible for the increase in illness. However, it does support the assertion that it is not wise to live in damp, mouldy buildings.

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Why Are There No Standards For Mould Exposure?

Health hazards from exposure to environmental moulds and their metabolites relate to four broad categories of chemical/biological attributes.

These materials may be:

  1. Irritants
  2. Allergens
  3. Toxins
  4. And rarely Pathogens

Different mould species may be more or less hazardous with respect to any or all of these categories. However, risks from exposure to a particular mould species may vary depending on a number of factors. Uncertainty is complicated further by a lack of information on specific human responses to well-defined mould contaminant exposures. In combination, these knowledge gaps make it impossible to set simple exposure standards for moulds and related contaminants.

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What Are The Knowledge Gaps Concerning Mould Exposure And Its Health Effects?

Chief among our knowledge gaps are: (1) defining how mycotoxins affect human health and (2) the health risks associated with mycotoxin, microbial volatile organic compound, allergen, and glucan exposures, particularly the proposed response to Stachybotrys mycotoxins associated with hemosiderosis.

However, the etiology of infectious fungi is relatively well understood. Conversely, mechanisms responsible for allergic sensitization, contact dermatitis, hypersensitivity pneumonitis, and inhalation fevers vary from incompletely characterized to entirely unknown. Predisposing host factors, presumably under genetic control, influence individual susceptibility to environmental exposures. The psychogenic/psychosocial contribution to mould-related illness remains elusive.

The lack of meaningful exposure limits for most indoor air quality contaminants is a major obstacle to establishing regulatory standards for individual exposure to airborne contaminants. The same is certainly true for moulds. Until microbiological methods for demonstrating mould concentrations in the environment are standardized and reproducible, epidemiological studies necessary to determine dose-response can only suggest association, not cause and effect, with respect to mould exposures and health effects.

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Why Is There Controversy About The Health Effects Of Exposure To Mould Growth?

Not all health effects of moulds are controversial. Fungal infections are well known. Fungal allergies are also well known and accepted among medical experts, although the allergens themselves are poorly characterized. Infections and allergies have objective and well-established clinical effects. These effects can be measured and reproducibly demonstrated, and the mechanisms are fully understood. The health effects caused by consuming mouldy food or feed that contains mycotoxins are also well known. Regardless of these controversies, mould growth in the built environment is unacceptable from the perspectives of potential adverse health effects and building performance.

Other health effects have been proposed for mould metabolites that are irritants or mycotoxins, and plausible mechanisms exist for health effects due to these mould metabolites. However, the clinical relevance of these mycotoxins and irritants under realistic airborne exposure levels is not fully established. Further, supporting evidence for other health effects is based on case studies rather than controlled studies, non-reproduced studies, or subjective symptoms.

Case studies do indicate the possibility or plausibility of an effect. Unfortunately, such studies cannot address whether an effect is common or widespread among building occupants. Results from non-reproduced studies may be false or are not confirmed by well-designed follow-up studies. In large epidemiological studies, general symptoms have been associated with moisture-damaged and presumably mouldy buildings. Many of the reported symptoms are subjective and difficult to quantify. Results are confounded by the fact that the association is general, and mould is not the only possible cause of the symptoms. Neither condition proves that mould is not a cause. 

Since much remains unproven, controversy has developed around the presumed health effects attributed to mycotoxins. This controversy is intensified since the health effects are often serious and sometimes are claimed to be permanent. Dampness in buildings is associated with respiratory effects, but the extent to which mould contributes to these effects is unknown. Some health effects from mould exposure remain controversial because of the potentially significant consequences; yet crucial and legitimate scientific questions remain unanswered. Our incomplete knowledge of noninfectious health effects related to mould exposure is due to limited research support and lack of documented health effects in the context of well-defined exposures. Bear in mind that environmental investigations must also be interpreted in context with medical and epidemiological information for infectious diseases from environmental sources. For example, finding Legionella colonization of a water supply serving an Immunocompromised population would have potential health significance whether or not there were cases of infection, but finding mould spores in ambient air has little significance unless people are getting sick from direct exposure.

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The Facts About Mould: Removal and Remediation


How Should A Building Be Evaluated For Mould Growth?

Check building materials and spaces for visible mould and signs of moisture damage indicating a history of water leaks, high humidity levels, and/or condensation. Any occupant complaints or reported health problems should be noted as well as any musty or mouldy odors.

Components of the buildings ventilation system should also be inspected. A moisture meter is often helpful in identifying wet or damp building materials. If mould growth or moisture problems are found, the air pressure differentials between the area of growth and surrounding areas should be determined. Potential air pathways from the source should also be characterized to determine its impact on the building and its occupants.

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When Is Sampling Necessary In A Building Evaluation?

Sampling may not be necessary. If visible mould is present, then it should be remediated, regardless of what species are present and whether samples are taken. In specific instances, such as cases where health concerns are an issue, litigation is involved, or the source(s) of contamination is unclear, sampling may be considered as part of a building evaluation. Sampling is needed in situations where visible mould is present and there is a need to have the mould identified.

If mould is suspected, but not visibly detectable after an inspection, then sampling may reveal evidence of mould amplification or reservoirs indoors. If mould is being removed and there is a question about how far the colonization extends, then surface or bulk sampling in combination with moisture readings may be useful. Sampling for airborne mould spores can indicate whether the mix of indoor moulds is typical of the outdoor mix or, conversely, typical or unusual at that time.

Professionals experienced with mould issues and familiar with current guidelines must conduct any sampling. If samples are taken, regardless of the purpose, the results should help answer a clear question. Sampling without a specific purpose greatly increases the chances of generating useless data. Note that laboratories vary in experience and proficiency; using an AIHA EMLAP-accredited lab is recommended.

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With No Mould Exposure Standards, How Do I Interpret My Sampling Results?

A useful method for interpreting microbiological results is to compare the kinds and levels of organisms detected in different environments. Usual comparisons are indoors to outdoors or complaint areas to noncompliant areas. Specifically, in buildings without mould problems, the qualitative diversity (types) of airborne fungi indoors and outdoors should be similar. Conversely, the dominating presence of one or two kinds of fungi indoors and the absence of the same kind outdoors may indicate a moisture problem and degraded air quality. Also, the consistent presence of certain fungi such as Stachybotrys chartarum, Aspergillus versicolor, or various Penicillium species over and beyond background concentrations may indicate the occurrence of a moisture problem and a potential atypical exposure. Generally, indoor mould types should be similar and levels should be no greater than outdoor and noncompliant areas. Analytical results from bulk material or dust samples may also be compared to results of similar samples collected from reasonable comparison areas. Comparisons of total bacterial levels indoors versus outdoors may not be as useful as with fungi, since natural bacteria reservoirs exist in both places. Comparisons of the specific types of bacteria present, excluding those of known human origin, can help determine building-related sources.

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If Mould Is Present, What's The Best Way To Get Rid Of It?

The answer depends on how much mould is present and where it is located. If the mould is on furnishings or boxes simply discard the materials. Mouldy materials are not considered hazardous waste; they can be sent to a regular landfill. However, it is smart to seal the mould material in heavy plastic to protect the people who handle it in transit and prevent spreading large amounts of the mould into the building as you carry the material out of it.

If the mould is on a hard surface but occupies less than 10 square feet wash the area with soapy water (scrubbing with a brush may be necessary), rinse and allow the area to dry before repainting. If you have asthma, severe allergies and a weaken immune system get someone else to do the clean up.

Larger areas (greater than 10 square feet in area) should be cleaned by someone with experience in doing this type of work. Remember, determine what caused the moisture problem and correct that problem. Otherwise, mould is likely to recur.

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Is It Possible To Completely Eliminate Mould From The Inside Of A Home Or Office Building?

The answer depends upon what is meant by completely eliminate mould. To keep a building completely free of mould spores requires very efficient air filtration and is only accomplished in special situations such as hospital operating rooms and manufacturing clean rooms. Remember, mould spores are in the outside air virtually all the time and some of them will get inside buildings.

However, it is possible to keep mould from growing inside a building. Moisture control is the key to controlling mould in interior spaces. Air filtration can contribute to lowering mould spores in the air but is secondary to moisture control.

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Does Mould Remediation Always Require Isolation/Containment?

Mould remediation should always require some level of isolation of materials or containment. The lower level of containment or isolation involves sealing removed mouldy materials in a plastic bag for disposal. Local area or full area containment decisions should be made based on the size of the area of growth and the potential for occupant exposure or building contamination without containment. These decisions should be based on an understanding of the full scope of mould contamination, including visible and hidden mould sources.

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Should I Use Bleach To Get Rid Of Mould?

No. Although bleach will kill and decolorize mould, it does not remove mould. Dead mould can still cause allergic reactions. It is not necessary to kill mould to remove mould. Soap, water and scrubbing can remove mould from hard surfaces. The Environmental Protection Agency (EPA), the Center for Disease Control (CDC) and the New York City Health Department agree that bleach or other biocides should not routinely be used to clean up mould.

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Are Biocides Useful Or Required In Remediation Projects?

Biocides are disinfectant chemicals used to kill germs. In most mould remediation projects, biocides are not a substitute for thorough cleaning. Biocides are of limited use in remediation of indoor mould contamination for two main reasons:

  • Biocides do not remove allergens that can lead to allergies in sensitive individuals nor do they remove other metabolites from mould that can cause adverse reactions in some people. Even though the application of biocides may kill mould spores, the only way to remove the allergens and other metabolites is through the physical elimination of mould and mouldy materials by thorough cleaning or removal.
  • Commonly used biocides do not effectively kill moulds. For example, active fungal growth on a surface may produce a spore density of 1 million spores per square inch. Treating this site with a biocide that has an effectiveness of 99.999% would still leave an estimated 10 viable spores per square inch. As such, mould growth may recur if the underlying moisture problem is not resolved.

Biocidal treatments are indicated only when the contaminant is one of the few fungi that are known to cause human infection. This is particularly important in health-care facilities or other places with occupants who have impaired immune systems or who may be more susceptible to infections.

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How Do I Know When The Mould Clean Up Is Finished?

The mould cleanup is finished when there is no visible mould remaining and there is no dust or dirt remaining that could contain large amounts of mould and mould spores. Routine clearance testing for mould is not necessary. Leaving a few mould spores behind is not a problem if the underlying moisture problem has been corrected. Remember that mould spores are virtually everywhere. Even if all mould and mould spores are removed as part of the cleanup, spores from outside will re-enter that space. The spores wont be able to grow unless water is also present.

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The Facts About Mould: Further Information


Where Can I Get More Information About Mould?

Environmental Protection Agency

Information on Mould/Moisture/Mildew Available in HTML and PDF.

Center for Disease Control
Information on Mould Various topics on mould including information about strains.

New York City Department of Health
Guidelines on Assessment and Remediation of Fungi in Indoor Environments. A variety of informational resources regarding mould.

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