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Indoor Mold

Indoor Mold - Parts 1 and 2

Part 1 - Mold and Indoor Air Quality

Indoor Air Quality and Your Health

Over the past several years, we have all heard about illnesses and structural problems within homes as a result of exposure to toxic mold and fungal microorganisms. Likewise, there seems to be an increase of allergy symptoms and hypersensitivity, particularly in young children, as a result of mold. Mold can affect anyone (whether allergic or not). And, according to the Environmental Protection Agency (EPA), "Mold can be found almost anywhere." Learning more about mold and its causes in indoor settings is the first step in knowing how to maintain a quality home environment and avoid the adverse health effects that mold is known to bring.

Building Related Illness (BRI) and Sick Building Syndrome (SBS) are terms used when health symptoms are experienced while in a particular building (including the home), with relief from these symptoms only occurring after leaving the site. Causes of BRI and SBS are often related to poor Indoor Air Quality (IAQ). Poor IAQ can be caused by many different factors such as:

  • Inadequate or contaminated ventilation systems
  • Humidity or moisture problems
  • Exposure to indoor molds and bacteria
  • High particle (house dust) levels
  • High allergen levels (dust mites or cockroaches, pollen, mold, animal dander)
  • Chemical exposure to building materials or cleaning agents
  • Pesticide use
  • Environmental tobacco smoke
  • Exposure to the byproducts of combustion (carbon monoxide)

Americans generally spend more than 90% of their day indoors. Thus, exposure to indoor pollutants can have a considerable health impact on individual sufferers, as well as on schools and businesses. In fact, indoor levels of pollutants may be 2-5 times ‒ and occasionally more than 100 times ‒ higher than outdoor levels, according to EPA studies of human exposure to air pollutants. IAQ problems may eventually lead to increased medical expenses due to health problems (direct costs), and lost productivity due to discomfort or absenteeism (indirect costs).

Mold and Its Dangerous Effect on Indoor Air Quality

Mold (also called mildew) is an organic substance from the Fungi kingdom that comes in a variety of species and colors, and is often recognized by its musty smell. Mold has been implicated as a major cause of Building Related Illness (BRI) and Sick Building Syndrome (SBS). Studies have shown that exposure to indoor mold can induce respiratory illness in adults, and can cause early onset asthma or respiratory allergies in children.

"Molds produce allergens (substances that can cause allergic reactions), irritants, and in some cases, potentially toxic substances (mycotoxins). Inhaling or touching mold or mold spores may cause allergic reactions... They [allergic reactions] can be immediate or delayed. Molds can also cause asthma attacks in people with asthma who are allergic to mold. In addition, mold exposure can irritate the eyes, skin, nose, throat, and lungs of both mold-allergic and non-allergic people."

From the EPA - A Brief Guide to Mold, Moisture, and Your Home. For a downloadable version, please click here.

A 1999 Mayo Clinic Study found that 96% of chronic sinus infections were caused by molds. Molds have also been implicated in other non-allergy related illnesses.

"Some symptoms and maladies have been attributed to the toxic effects of fungi [mold] in indoor environments. Certain fungi can produce toxins (mycotoxins) at varying levels... The reported symptoms from exposure to mycotoxins indoors include headaches, irritation, and nausea/loss of appetite, but are often non-specific (e.g. fatigue, inability to concentrate/remember)."

From the New York City Department of Health & Mental Hygiene - Guidelines on Assessment and Remediation of Fungi in Indoor Environments. For a downloadable version of these guidelines, please click here.

Types of Mold You Should Know About

micromold2There are a number of different molds that can be found in the home. Some of these molds favor outdoor environments for growth but readily enter the home in microscopic spore form by circulating through doorways, windows, and systems like heating and air conditioning units. Mold can grow on almost any substance as long as it has a carbon-based food source, moisture, oxygen, and the temperature is between 40 and 100°F. When mold spores land on a spot meeting all these conditions, it sets the stage for mold growth.

According to the Centers for Disease and Control (CDC), "The most common indoor molds are Cladosporium, Penicillium, Aspergillus, and Alternaria," and so we've focused on these here. Additionally, while the CDC indicates it does not have enough information to determine the degree to which Stachybotrys might be present in homes or buildings, we've added it here because of its ability to cause serious health effects. By the way, the CDC advises that regardless of what type of mold you may find or have that, "All molds should be treated the same with respect to potential health risks and removal."

We've listed these molds at the genus level, but there are sometimes many different species – some more toxigenic (i.e., capable of producing toxins) than others. For example, Aspergillus has well over 100 species including flavus, ochraceus, and parasiticus.

Alternaria A large spore mold that can deposit in the nose, mouth and upper respiratory tract causing an allergic response. Indoors, it is often found in carpets, textiles, house dust, and potentially damp areas like window frames and showers. It can also be found in plant soil.
Aspergillus Usually found in warmer climates in areas of water damage or extreme dampness. Aspergillus species are also commonly found in house dust. Many species produce mycotoxins, which may be associated with disease in humans and some animals. Also found in building materials, and in fall leaves and other decomposing matter like compost piles.
Cladosporium The most commonly identified outdoor fungus, but it can easily enter into the house through the HVAC and other airflow entryways. Cladosporium also has an indoor species that grows on textiles, wood and other porous, damp areas. Both indoor and outdoor species are triggers for hay fever and asthma symptoms.
Penicillium A very common mold known to cause allergies, hay fever and asthma. Species may be found growing on wallpaper, wallpaper glue and decaying fabrics in water-damaged buildings or homes. It is also found in carpet and in interior fiberglass duct insulation. Some species can produce mycotoxins.
Stachybotrys Pronounced (stack-ee-BOT-ris), this is an especially toxic black or dark greenish-black mold that produces airborne toxins (mycotoxins) that can cause serious breathing difficulties, memory and hearing loss, dizziness, flu-like symptoms, and bleeding in the lungs. Stachybotrys requires excessive moisture to thrive (usually running water) and is a slimy black mold. Fortunately, Stachybotrys is not found in homes as often as the other molds listed above.

From the University of Minnesota's Indoor Air Quality webpage, and the
Environmental Microbiology Laboratory

How Do I Know If I Have A Mold Problem?

couchmold1If you think your home or office might have a mold problem it's time to do a little detective work. First, consider your symptoms or those of your loved ones. When you leave the suspected area do the symptoms dissipate? Do you smell anything different when you enter the area (a musty smell for example)? Are there any visible signs of mold growth (even a little), such as like shown in the pictures? Carpet, dry wall, wood, attic space and insulation, and even bare earth in a crawl space should be checked. Do you or have you ever had a water leak in any part of your home? The source could be rain, plumbing, an appliance or condensation.

ceilingmoldIf you don't see any visible signs of mold in the house, don't breathe a sigh of relief just yet. Unfortunately, there are many places for indoor mold to hide. For example, indoor mold can be behind baseboards, under carpeting or wallpaper, in the ventilation system, or behind drywall. You should also be wary of any area that has been wet at one time but now appears dry: even non-living mold spores can cause adverse health symptoms. While hidden mold is more difficult to detect, it can often be recognized by odor. If you suspect you might have a mold problem, the next step is to utilize a do-it-yourself mold test or contact a professional IAQ consultant for testing.

Mold Testing Techniques

Testing is an effective and recommended way to discover if mold is present, how much mold is present, and what types of mold are present. Having said that, please realize that these tests should be used as an initial screening procedure and that further testing may be needed to fully characterize your environmental conditions. There are two main test methods available that are very easy to use – the "Air Sample" method, and the "Tape-Lift" method. Each has its advantages and limitations.

PLEASE NOTE:  The tape-lift method (described below) requires that you "disturb" the mold by placing a piece of tape on the affected area and lifting it off, whereas the air sample method does not. Therefore, the air sample method is recommended when there is a significant amount of mold, or if you have allergies or asthma, are immune compromised, or have any other serious medical risk.

moldresultsThe "Air Sample method" usually utilizes a culture plate (or petri dish) that must be refrigerated until time of use. It is then left open in the test area for about an hour. Live mold spores that are in the air then settle on the plate and will grow on the media over the course of 5 to 7 days. The plates are sent to a test lab where they are carefully examined. This method allows for the specification of different types of live molds at the genus level and can show how severe the problem is based upon how many colonies grow on the plate.

It is important to note that this test method is a "snapshot" view of live airborne mold spore in the location tested. But mold spores can be released intermittently, based upon activity levels in the area, relative air pressure, and other variables, so the air sample snapshot may not reflect the true nature of the condition. Also, mold spores don't have to be live to cause health problems, and dead ones won't grow on the plates. Finally, molds grow at different rates. Slow growing molds (like Stachybotrys) could become hidden on the culture plate by the more rapid growing molds.

micromold4The "Tape-Lift method" of mold detection, as the name implies, utilizes a peel-off tape strip that is pressed on the surface to be tested. The sample is then applied to a glass slide and read at a test lab under a microscope at 400 to 1000 times magnification. Spores are identified by visual characteristics, such as size, shape, texture, and color. A heavy load of background material on the slide ‒ like dust, dirt or other debris ‒ might obscure the view of any mold spores present. A report is sent, usually showing a semi-quantitative estimate at the genus level. Because some spores look the same under a microscope (such as Penicillium and Aspergillus) they are listed together. And, because there are literally thousands of different spore types, you may sometimes see spores reported as "unidentifiable." Because tape-lift tests read both living and non-living spores, this sampling method reveals an historical account of what has occurred in an area over time rather than a snapshot of what is currently in the air.

A Case Study

Identification and subsequent remediation of indoor mold growth and related contaminants in a home, office or school can result in significant health improvements, as seen in the case of this asthmatic child:

A two year-old boy with a history of poorly controlled asthma was brought to an allergy clinic for assessment by a pediatric allergist. His symptoms included a "smoker-like" cough, nasal congestion, sneezing, eye irritation and wheezing. His family history for allergies was negative, and allergy skin testing demonstrated he was non-reactive to cats, dogs, cockroaches, dust mites, dust and mold allergens (with appropriate positive and negative controls).

The boy was prescribed anti-inflammatory inhalers, plus long and short acting B-agonists for breakthrough symptoms... In spite of the patient's medical regimen, the boy's symptoms persisted. Upon inquiry, his parents reported they had occasional rainwater entry into their finished basement. Mold testing (air and tape lift samples) in the home was recommended.

The mold investigation revealed there were elevated levels and types of mold spores in the finished basement (Stachybotrys, Cladosporium and Chaetomium), indicating indoor mold growth (amplification) had occurred in the area the boy used as his playroom.

The family arranged for environmental remediation, including hiring a qualified (certified) professional to remove the contaminated building materials (in accordance with NYC Guidelines on Assessment and Remediation of Fungi in Indoor Environments), steam-cleaning the carpets, using a vacuum cleaner with a high-efficiency particulate-arresting (HEPA) filter equipped with microfiltration vacuum bags, installing a furnace filter, and cleaning the ventilation system.

Upon completion of the remedial procedures, the patient's health improved dramatically. He was gradually weaned off his medications and remained asymptomatic... Six years later, the boy continues to do well. The physicians concluded remediation of the patient's environment and implementation of appropriate environmental controls were essential to the boy's improved outcome.

From Respiratory Reviews, April 1999.

Special Thanks

We are honored to have had Sue Flappan MS, CIH as a contributor to this webpage. Sue is a Certified Industrial Hygienist, and an expert on mold in homes, businesses and schools. Mrs. Flappan has been featured on Dateline NBC (1999) and the Discovery Health Channel, and has made numerous presentations at the local, regional and national level for organizations such as Environmental Protection Agency (EPA), American Industrial Hygiene Association (AIHA), and the American Academy of Allergy, Asthma and Immunology (AAAAI).

Part 2 - Mold Problems and Indoor Air Quality

Safety Precautions To Take When Around Mold

As we learned in Part 1, mold (a fungus, also called mildew) is an allergy trigger that can cause chronic sinusitis, itchy eyes, runny nose, and sore throat in millions of Americans. In addition, while molds themselves are not "toxic" or poisonous, some molds can be "toxigenic," meaning they produce toxins (more specifically mycotoxins), emitting spores that can cause symptoms in otherwise healthy people ranging from cough and wheeze to dull headache, nausea, and even mental lapses. For those with mold allergies or asthma, mycotoxins can also cause hyper-responsive allergic or asthmatic symptoms. For these reasons, it is wise to limit your exposure to mold and mold spores by taking appropriate safety measures when around it. While your environment may not host such dangerous mold species as Stachybotrys, it is still wise to use caution when beginning a mold clean-up project.


8233Protect Your Lungs:
 Wear at least an N95-rated respirator/mask when working around mold. These masks, when worn properly, will prevent mold spore, as well as other allergens and microparticles from entering your lungs. The N95 rating was developed by the National Institute for Occupational Safety and Health (NIOSH), and means the mask media will filter 95% of all non-oil based airborne particulates. For even higher filtration, a NIOSH N99-rated mask will filter 99% of all non-oil based airborne particulates, and an N100-rated mask 99.97%. NIOSH also developed "R" and "P" ratings to aid in the selection process of respirators/masks where both oil-based and non-oil based particles are present. N95-rated masks and higher are used by most professionals in the mold remediation business.


gloves2Protect Your Hands & Skin:
 Wear heavy-duty gloves, preferably those that extend to the middle of the forearm, to prevent inadvertent contact with the mold contaminated area. For small projects, you can also use disposable vinyl gloves – some people like to wear these under the heavy-duty gloves. Remember to choose gloves that are latex free if you are sensitive to latex.

Protect Your Eyes:  Mold allergen is an irritant causing many to have runny nose and watery eyes. Goggles are an important defense against getting potentially dangerous mold spore in your eyes. Safety Goggles that don't have ventilation holes are best. Standard swimming goggles can be used for smaller projects, but may fog if used extensively.

Cleaning Guidelines

A mold problem in your home may not call for an expensive remediation specialist. In fact, you can breathe easier knowing that mold remediation is often as simple as finding the source of moisture and eliminating it. It would also be helpful to know the history of your home or apartment complex. For example, have you or previous owners experienced water damage or leakage of any kind? Has the foundation been inspected for moisture or seepage? Below are some practical, cost-saving cleaning tips to help you eliminate unsightly mold stains, and to prevent further growth:

  1. Repair all moisture leaks. Mold can only thrive in areas with moisture. Water leaks and damage should be repaired within 48 hours of occurrence in order to prevent mold growth.

  2. Before cleaning an affected area, lightly spray it with water or your chosen cleaning solution. This will prevent the spores from becoming airborne as you clean. And remember to wear gloves, goggles, and a mask as noted above.

  3. Scrub mold off of hard surfaces with cleaner and let dry completely. If you use a fume-free, chlorine-free cleaner like NAS-12, just spray it, let it sit for a few minutes, then lightly scrub, rinse and let dry. Some porous and absorbent materials (such as ceiling tiles) that cannot be cleaned completely may need to be thrown away or replaced entirely.

  4. Do not just paint or caulk over a moldy surface. First, clean the area thoroughly, let it dry completely (24 hours if you have used a chlorine-based product), then treat hard surface areas with No More Mildew (a protective layer that prevents mold from regrowing for up to 2 years), or paint with a mold-retardant like MX-3 Mildewcide added to the paint.

  5. Clean your showers, windowsills, kitchens, basement and other areas that might be prone to moisture and mold growth. Treat these surfaces with a mold inhibitor such as No More Mildew or AllerTech Mold & Mildew Stain Preventer.

  6. Closely monitor and clean appliances such as humidifiers, water-based vaporizers, and air conditioning units that generate or collect moisture. Note: Arizona and other desert-state residents may know about evaporative swamp coolers. Believe it or not, despite the dry climate, these cooling units are major mold culprits. Regularly clean your swamp cooler to prevent mold spore from growing and disseminating into the air. Use Goodmorning Purifying Spray on the vents and coils of any of these appliances to prevent mold.

  7. Basements have all the conditions that help mold thrive. Keep your basement clean by removing moldy articles, cleaning all surface molds, then spraying floors, walls and joists with a mold preventative. Use a dehumidifier to remove excess moisture.

  8. Clean the air in your environment by utilizing a HEPA air cleaner. HEPA stands for High-Efficiency Particulate Arrestor, and is a NASA-developed technology that will remove airborne mold spore and other harmful allergens (99.97% of them, in fact!) by circulating and purifying the air.

  9. You can also clean air of mold spores with a mold zapper or Airfree air purifier. These filterless devices use heat to kill mold spores and other airborne microorganisms that pass through them through a process known as convection. For best effect, these very safe devices are meant to run 24/7. They use far less energy than air purifiers with motors, and there are no fans, so they run silently! They also tend to be much smaller than typical room air purifiers.

Following is a handy guide from the EPA outlining some common mold-affected areas and the best methods for cleaning them. Again, remember to wear gloves, goggles, and an N95-rated mask during cleanup. Also, please note that these guidelines are for surface areas of 10 square feet or less. If the evidence of mold covers an area of more than 10 square feet, the EPA recommends you should seek professional consultation, as it may be endangering your health and could require professional containment:

Material or Finishing Affected
Cleanup Methods
Personal Protective Equipment
Books and Papers 3
N95 respirator, gloves, and goggles
Carpet and Backing 1, 3
Concrete or cinder block 1, 3
Hard surface, porous flooring (linoleum, ceramic tile, vinyl) 1, 2, 3
Non-porous, hard surfaces (plastic, metals) 1, 2, 3
Upholstered furniture and drapes 1, 3
Wallboard (drywall and gypsum board) 3
Wood surfaces 1, 2, 3
  • Method 1:  Wet vacuum (in the case of porous materials, some mold spores or fragments will remain in the material, but will not grow if the material is completely dried). Steam cleaning may be an alternative for carpets and some upholstered furniture.
  • Method 2:  Damp-wipe surfaces with plain water or with water and detergent solution (except on wood ‒ use wood floor cleaner); scrub as needed.
  • Method 3:  High-efficiency particulate air (HEPA) vacuum after the material has been thoroughly dried. Dispose of the contents of the HEPA vacuum bag in well-sealed plastic bags.

From the U.S. EPA - Mold Remediation in Schools and Commercial Buildings
Table 2: Guidelines for Remediating Building Materials with Mold Growth Caused by Clean Water.

Prevention: It's Easier Than You Think!

Even if you live in a very humid area or your hometown has seen more rain than usual this summer, you are not necessarily resigned to having mold problems. The following tips will help you to keep moisture and humidity from turning into a potentially dangerous mold problem.

Tips on Preventing and Controlling Moisture and Mold

  1. Monitor humidity and temperature levels in your home regularly. According to the EPA, humidity levels should not be above 60% (ideally, between 30-50%).

  2. Provide adequate ventilation and air circulation in the home by installing exhaust fans and opening room doors and windows (individuals allergic to pollen or sensitive to other outdoor pollutants should use discretion about keeping windows open or alternatively use a window filter).

  3. Keep a close eye on areas prone to condensation. Cover cold surfaces with insulation and increase the air temperature when condensation begins to appear.

  4. In the bathroom, run the vent fan or open windows during and after a shower so that the moisture can dissipate. Use a mildew resistant shower curtain that can easily be laundered. Avoid using carpeted surfaces that absorb moisture. Use a mold-inhibiting paint or MX-3 Mildewcide Paint Additive.

  5. Avoid foam-rubber upholstery and bedding items, as they are more prone to mold growth. Bedding encasings are a good precaution against mold growth, and they keep away the dust mites too!

  6. Keep a limited number of houseplants, and try adding a mold-preventative to the soil.

  7. Vent your clothes dryer to the outside of the house, and do not let clothes sit for long in damp heaps, in or out of the washer.

  8. Periodically check carpet laid directly on concrete surfaces, as the carpeting can absorb moisture. Consider covering concrete floors or crawl-space floors in moisture-prone areas with plastic sheets, tarps or other moisture barrier.

  9. If necessary, use an electric dehumidifier to keep the relative humidity below 60%.

When it May Be Time to Get Help

  • Duct Cleaning is normally recommended for homes that are 15 to 20 years old, for homes that have been flooded or suffered water damage, and in instances where a mold test reveals mold spore within your ducts and component parts.

    Should you deem it necessary to have your ducts cleaned, be aware that it will stir up the allergens within your ductwork. As a precaution, we recommend that children and sensitive adults limit their exposure to the air in the home for 24 hours while a HEPA air filter purifies the new air.

  • As stated in the EPA guidelines above, mold problems affecting areas less than 10 square feet are manageable by homeowners. When the affected area is greater than this, the EPA and other agencies advise seeking professional assessment. If you are concerned with specific items that may have mold infestation, particularly those of sentimental or monetary value, consult a specialist to help you clean these items. Finally, should a do-it-yourself mold test reveal the presence of Stachybotrys mold, you should avoid any exposure to the area and seek professional help immediately due to the high toxicity of this dangerous mold.

You can find a mold remediation specialist by:

  • Visiting the American Industrial Hygienist Association (AIHA) website and searching for a consultant in your area.

  • Click here for AIHA's 2014 Consultants Listing ‒ Comprehensive Directory of Occupational & Environmental Health and Safety Professionals.

  • Checking the yellow pages under Mold and Mildew or Indoor Air Quality. Most telephone directories list a variety of specialists in remediation, restoration, conservation, furniture repair, cleaning, and more.
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