Frequently Asked Questions About Mold
By Dr. Nathan Yost, MD., Building Sciences Corporation , 03/27/2008
Source: http://www.realtor.org/realtororg.nsf/pages/moldfaq

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

How does mold get into a building?
Molds are decomposers of organic material such as wood, plants and animals. Mold and mold spores are found in high concentrations wherever there is dead matter such as a pile of leaves, manure or compost. Mold 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 molds make under certain conditions.

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

Some molds 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.

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

How much mold exposure is harmful?
No one knows the answer to this question for several reasons. Individuals are very different with respect to the amount of mold exposure they can tolerate. Children under the age of one year may be more susceptible to the effects of some molds than older individuals. Measuring or estimating “exposure” levels is very difficult. “Exposure” means the amount of mold (microscopic spores and mold 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 mold in the walls but very little of that mold is getting into the air stream. In that case the people working or living in that building would have little mold exposure.

Can mold exposure cause brain damage or death?
Although some “experts” claim that individuals have brain damage or have died because of exposure to mold and especially mold toxins, there is no good science at this time to support these claims. Consequently it is prudent to minimize one’s exposure to really moldy environments. By “really moldy” we mean where there are large visible areas of mold (more than a few square feet) or the building has a “musty” odor because of hidden mold 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 mold that is responsible for the increase in illness. However, it does support the assertion that it is not wise to live in damp, moldy buildings.

Does tighter building construction promote mold development?
Tighter building construction does not by itself promote mold growth, but tight construction combined with some poor choices in design, building materials or operations can increase the probability of mold 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 mold 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 mold 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).

Do new building materials (e.g. drywall or paper faced gypsum board) promote mold growth?
Mold needs water, a nutrient source, oxygen and favorable temperature to grow. Many species of mold 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 mold to get nutrients from the paper. But unless there is enough moisture present mold can’t grow on the paper. If paper faced gypsum board is kept dry, it can be used and still not have mold. 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 mold growth.

Are there reliable tests to indicate the presence of mold?
Almost all of us already have two effective mold detectors: our eyes and our noses. If black or green discoloration is noticed that is fuzzy in appearance and is in a location that is damp or had been damp, it is almost certainly mold. If a building smells musty, there probably is mold somewhere; the mold may be on boxes stored in a basement or in walls or in the crawl space. If you want to find mold, look for the presence of water or a location where water was likely to have been. If there is still any question about whether the black stuff is mold, have a reliable laboratory examine the material. All you need to know is whether mold is seen when the material is examined under the microscope.

An increasing number of companies are offering “air testing for mold.” On the surface this seems like a reasonable thing to do. The problem, however, is that the results of most air sampling for mold are meaningless for two reasons. Air sampling for mold was not developed to determine if an environment was safe or had a dangerous level of mold in the air. Air sampling was developed to help identify the location of a hidden reservoir of mold. If the source of mold is already identified, air sampling does not provide additional meaningful information. Furthermore, safe or toxic levels of air borne mold have not been established. An individual air sample for mold provides a “snapshot” of what was in the air during the few minutes of sampling. The results may not be indicative of the amount of mold that is in the air during most of the day.

Air sampling for mold should be done either to obtain an answer to a question that cannot be answered without the air sampling or to obtain data as part of a research project. The Center for Disease Control (CDC), the U.S. Environmental Protection Agency (EPA) and the American Conference of Governmental Industrial Hygienists do not recommend routine air testing for mold.

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

If the mold 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, mold is likely to recur.

Is it possible to completely eliminate mold from the inside of a home or office building?
The answer depends upon what is meant by “completely eliminate mold.” To keep a building completely free of mold spores requires very efficient air filtration and is only accomplished in special situations such as hospital operating rooms and manufacturing “clean rooms.” Remember, mold spores are in the outside air virtually all the time and some of them will get inside buildings.

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

Should I use bleach to get rid of mold?
No. Although bleach will kill and decolorize mold, it does not remove mold. Dead mold can still cause allergic reactions. It is not necessary to kill mold to remove mold. Soap and water and scrubbing can remove mold 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 mold.

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


Where can I get more information about mold?
Environmental Protection Agency
Information on Mold/Moisture/Mildew. Available in HTML and PDF.

Center for Disease Control
Information on Mold. Various topics on mold 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 mold.

Source: http://www.moldacrossamerica.org/notobleach.htm

Source: http://www.peakpureair.com/chlorine-bleach-mold.htm

(1) The object to killing mold is to kill its “roots”. Mold remediation involves the need to disinfect wood and wood-based building materials, all of which are porous materials. Thus, chlorine bleach should not be used in mold remediation as confirmed by OSHA’s Mold Remediation/ Clean Up Methods guidelines. The use of bleach as a mold disinfectant is best left to kitchen and bathroom countertops, tubs and shower glass, etc.

(2) Chlorine Bleach does kill bacteria and viruses, but has not been proven effective in killing molds on non-porous surfaces. Bleach itself is 99% water. Water is one of the main contributors of the growth of harmful bacteria and mold. Current situations using bleach re-grew and regenerated mold and bacteria twice the CFU counts than were originally found before bleaching, within a short period of time. Bleach is an old method used for some bacteria and mold. It is the only product people have known for years. The strains now associated within Indoor Air quality issues are resistant to the methods our grandmothers employed to clean-up mold..

(3) What potential mold 'killing' power chlorine bleach might have, is diminished significantly as the bleach sits in warehouses, on grocery store shelves or inside your home or business 50% loss in killing power in just the first 90 days inside a never opened jug or container. Chlorine constantly escapes through the plastic walls of its containers.

(4) The ionic structure of bleach prevents Chlorine from penetrating into porous materials such as drywall and wood---it just stays on the outside surface, whereas mold has enzyme roots growing inside the porous construction materials---however, the water content penetrates and actually FEEDS the mold---this is why a few days later you will notice darker, more concentrated mold growing (faster) on the bleached area.

(5) Chlorine Bleach accelerates the deterioration of materials and wears down the fibers of porous materials.

(6) Chlorine Bleach is NOT registered with the EPA as a disinfectant to kill mold. You can verify this important fact for yourself when you are unable to find an EPA registration number for killing mold on the label of any brand of chlorine bleach.

(7) Chlorine bleach off gases for a period of time. Chlorine off gassing can be harmful to humans and animals. It has been known to cause pulmonary embolisms in low resistant, and susceptible people.

(8) Chlorine bleach will evaporate within a short period of time. If the area is not dry when the bleach evaporates, or moisture is still in the contaminated area (humidity, outside air dampness), you could re- start the contamination process immediately and to a greater degree.

(9) Chlorine is a key component of DIOXIN. One of the earliest findings of dioxin's toxicity in animals was that it caused birth defects in mice at very low levels. This finding led to dioxin being characterized as "one of the most potent teratogenic environmental agents". The first evidence that dioxin causes cancer came from several animal studies completed in the late 1970's. The most important of these, published in 1978 by a team of scientists from Dow Chemical Company, led by Richard Kociba, found liver cancer in rats exposed to very low levels of dioxin. This study helped establish dioxin as one of the most potent animal carcinogens ever tested and, together with the finding of birth defects in mice, led to the general statement that dioxin is the "most toxic synthetic chemical known to man."

If Not Bleach, What Can I use?

Chlorine Bleach and Mold Clean Up (Let's Set the Record Straight!)
(reprinted with permission from our friends at Spore°Tech Mold Investigations, LLC)

The Myth.
A myth exists concerning the use and “effectiveness” of chlorine bleach (sodium hypochorite) in the remediation of a mold problem. Mold remediation involves the removal and or clean up and restoration of mold contaminated building materials.

Opposing Views and Confusion.
Chlorine bleach, commonly referred to as laundry bleach, is generally perceived to be an “accepted and answer-all” biocide to abate mold in the remediation processes. Well-intentioned recommendations of the Environmental Protection Agency (EPA) and other federal, state and local agencies are perpetuating that belief. And confusing the issue is one federal agency, the Occupational Health and Safety Administration (OSHA), taking an opposing point of view by NOT recommending the use of chlorine bleach as a routine practice in mold remediation.

Does Bleach Really Kill Mold?
Will chlorine bleach kill mold or not—yes or no? The answer is yes, but with a caveat. That answer comes from The Clorox Company, Oakland CA, manufacturer and distributor of Ultra Clorox® Regular Bleach. The company’s correspondence to Spore°Tech Mold Investigations, LLC stated that their Tech Center studies supported by independent laboratories show that “…3/4 cup of Clorox liquid bleach per gallon of water will be effective on hard, non-porous surfaces against… Aspergillus niger and Trichophyton mentagrophytes (Athlete’s Foot Fungus)”. Whether or not chlorine bleach kills other molds and fungi, the company did not say. The words “hard, non-porous” surfaces” present the caveat. Mold remediation involves the need to disinfect wood and wood-based building materials, all of which are porous materials. Thus, chlorine bleach should not be used in mold remediation as confirmed by OSHA’s Mold Remediation/ Clean Up Methods guidelines. The use of bleach as a mold disinfectant is best left to kitchen and bathroom countertops, tubs and shower glass, etc.

Why Chlorine Bleach is NOT Recommended for Mold Remediation.
Chlorine bleach (sodium hypochlorite) is corrosive and that fact is stated on the product label. Yet the properties of chlorine bleach prevent it from “soaking into” wood-based building materials to get at the deeply embedded mycilia (roots) of mold. The object to killing mold is to kill its “roots”. Reputable mold remediation contractors use appropriate products that effectively disinfect salvageable mold infected wood products. Beware of any mold inspector or mold remediation company that recommends or uses chlorine bleach for mold clean up on wood-based building materials.

Chlorine Bleach Is Active Ingredient in New Mold & Mildew Products.
The appearance of new mold and mildew household products on store shelves is on the rise. Most are dilute solutions of laundry bleach. The labels on these mold and mildew products state that they are for use on (again) hard, non-porous surfaces and not for wood-based materials. Instructions where not to apply the products are varied. A few examples where the branded products should not be applied include wood or painted surfaces, aluminum products, metal (including stainless steel), faucets, marble, natural stone, and, of course, carpeting, fabrics and paper. One commercial mold and mildew stain remover even specifically states it should not be applied to porcelain or metal without immediate rinsing with water and that the product isn’t recommended for use on formica or vinyl.

Caveat Emptor!
Before purchasing a mold and mildew product, read and fully understand the advertised purpose of that product — and correctly follow the use instructions of a purchased product. The labeling claims on these new products can be confusing — some say their product is a mold and mildew remover while another says their product is a mildew stain remover and yet others make similar 'ambiguous' claims. Make double sure that the product satisfies your intended need on the surface to which it is to be applied. If your intention is to kill mold, make sure the product does exactly that and follow the directions for usage. Consumers may find that mixing their own diluted bleach solution will achieve the same results as any of the new mold and mildew products — keep in mind that the use of chlorine bleach is not for use on mold infected wood products including wall board, ceiling tiles, wall studs, fabric, paper products, etc.

Conclusion.
Laundry bleach is not an effective mold killing agent for wood-based building materials and NOT EFFECTIVE in the mold remediation process. OSHA is the first federal agency to announce a departure from the use of chlorine bleach in mold remediation. In time, other federal agencies are expected to follow OSHA’s lead. The public should be aware, however, that a chlorine bleach solution IS an effective sanitizing product that kills mold on hard surfaces and neutralizes indoor mold allergens that trigger allergies.

Using bleach can cause serious health problems. The fumes are very caustic and great care must be taken not to breath it in too much. It is also very damaging to clothing and carpeting, the human body, and the environment.

True or False - Does Bleach Kill Mold?
By Rob Forchet

Source: http://ezinearticles.com/?True-or-False---Does-Bleach-Kill-Mold?&id=1075538

Rob Forchet is helping to fight unwanted fungi with lots of tips and information. More info about these creatures can be found on his mold killer webpage at http://www.moldremovalsite.com

Article Source: http://EzineArticles.com/?expert=Rob_Forchet

Source: http://www.normipro.com/common/resources/bleach-does-not-kill-mold.html

A well-known expert in our area, when interviewed on a local New Orleans radio station, recently said, "When you have a mold problem, simply wash down the affected area with diluted bleach." We have seen FEMA handing out gallons of Clorox to flood-victims. Lowe's and Home Depot stock up pallets of the stuff whenever the impending doom of a threatening hurricane is close. This is one of the most widely publicized "urban legends". Bleach is a powerful oxidizer and can, in many instances, sanitize surfaces of certain types of bacteria but when you are faced with a wall covered in mold, bleach is NOT the product to use.

Eyebrows raise in disbelief every time I say the phrase "bleach doesn't kill mold." Some look at me as if I'm speaking another language and they are right. I am speaking the TRUTH. Bleach (active ingredient is Sodium Hypochlorite) is very effective in removing the discoloration but may leave the microflora that will enable the mold to return in exactly the same spot when conditions are right. So, "how do you know this," I'm asked.

Secondly, a black roof absorbs more heat than a lighter roof. Interestingly enough, in Florida, most homeowners choose a lighter roofing color for that very reason and yet, after a few years, they all end up the same color - black. We commissioned a study once in conjunction with the University of South Florida and found a substantial difference in attic temperatures once the roof was cleaned and the original lighter color was restored. I mean 30 degrees or more. That means by simply cleaning your roof to the lighter color you could make a major difference in the attic temperature and that would allow your air conditioning system to function more efficiently. In most cases the attic is the insulating space just above the air conditioned space so having those temperatures reduced substantially lowered the air conditioning bill.

Anecdotally, my wife wonders why she has to clean the same spot of mold on the bathroom tile month after month. Now she knows why. The mold has never been killed - it simply goes clear and then returns. Bleach will not kill the mold but a good biocide, or anti-microbial, will.

To underscore the validity of my claim, I suggest the "Journal of Forest Products" who commissioned a study by Oregon State University a couple of years ago. We have this article on our website where we have posted the abstract and the results. The "implications" of their testing showed exactly what we have been training for years. The stain disappears but the microflora remains and under the right conditions the mold will begin to grow.

In our Sanitization Protocol we recommend using GREEN technologies to remove surface mold. When you use the right kind of anti-microbial, the mold will be destroyed and the underlying bio-slime will be annihilated. I wish we had known about these kinds of technologies ten years ago when we were cleaning roofing systems. Instead of spending so much time protecting the landscape, we could have done an additional job or two. We could have completed more jobs and our subsequent warranty workload would have been reduced

http://www.thriftyfun.com/tf317227.tip.html