photo of a moldy basementIndoor Mold Contamination

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Complete guide to building mold contamination:

What to Do About Black Mold and other Indoor Air Quality IAQ Contaminants. How to test, remove, or prevent mold contamination. How to deal with mold related illness.

Tthis website answers just about any thing you want to know about what to do about mold contamination in buildings: how to find, test, remove, clean-up or prevent indoor mold contamination. These mold-action & indoor environment investigation & cleanup articles provide expert, un-biased information for owners, occupants, inspectors.

How to recognize mold, how to test for unsafe mold, how to clean up or remove mold, how to prevent mold contamination in buildings, and what mold related illnesses and symptoms have been reported are all discussed in depth.

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How to Find, Test, Inspect For, Remove, & Prevent Indoor Mold Contamination: what to do about mold in buildings

Stachybotrys spores (left) and structure (right)Here we give detailed and authoritative information and procedures for finding, testing, cleaning and preventing indoor mold, toxic black mold, green mold, testing building indoor air quality, and other sick house / sick building investigations.

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We also provide research articles on mold hazards and on the accuracy and reliability of various mold testing methods. We suggest the most effective building inspection and testing procedures for mold and similar indoor contaminants, and we provide a directory for expert services.

We give in-depth information about mold and other indoor air quality problems: causes of respiratory illness, asthma, or other symptoms such as neurological or psychological problems, air quality investigation methods, and remediation procedures such as mold cleanup, handling toxic mold contamination, and building or mechanical system repairs.

We offer advice on mold prevention and mold-resistant construction resistant to indoor problem molds such as the Aspergillus sp., Penicillium sp. and Stachybotrys chartarum groups.

To find what you need quickly, if you don't want to scroll through this index you are welcome to use the page top or bottom SEARCH BOX to search InspectApedia for specific articles and information.

Article Contents

Six Basic Approaches for Cleaning Up Indoor Air, Mold Contamination, or Similar Indoor Air Quality Problems

The US EPA lists six basic strategies for reducing the level of indoor air pollutants.[5] These six approaches, source removal, source substitution, source encapsulation, local exhaust, ventilation, exposure control, and education, can apply to an indoor airborne mold particle or mold-volatile-organic-compound MVOC odor as well.

We list and describe these approaches just below, followed by descriptions of key indoor mold contamination articles.

1. Source management of indoor air contaminants such as mold and MVOCs

The US EPA describes three indoor air pollutant source management approaches:

  1. [Mold] Source removal: for mold contamination, cleanup (MOLD CLEANUP GUIDE- HOW TO GET RID OF MOLD) is the most effective method.

    But preventing mold problems in the first place (MOLD PREVENTION GUIDE) is still better. For toxic, allergenic, or pathogenic mold contamination in buildings, this step is by far the most important.

    The location of both visible and hidden mold reservoirs must be found, and problematic (non-cosmetic) mold cleaned-up or in essence "removed". Any step other than cleaning off or removing mold, such as use of mold sprays, air cleaners, OZONE generators , will be comparatively ineffective, and worse, by making you think the mold problem has been handled, you may be fooled into leaving harmful mold in the building.

    If you suspect or know that there is a mold problem in a building you need to know the extent of cleanup needed, whether mold is cosmetic (inexpensive to clean), allergenic, or toxic (requiring special care).

    For small areas of mold contamination, generally where less than 30 square feet of contiguous mold is present, simple building cleaning and renovation procedures are all that's needed and testing is usually not appropriate. Most building mold contamination falls in this first category.

    At DO IT YOURSELF MOLD CLEANUP we provide suggestions for a do-it-yourself cleanup of small areas of mold.



    You need to know whether or not to hire a professional to inspect, test, find the mold, and write a cleanup plan, whether or not to hire a mold cleaning company, how to clean up mold, how to test to be sure the cleanup was successful, and how to prevent mold in the future.

    At MOLD / ENVIRONMENTAL EXPERT, HIRE ? we provide guidelines to help decide when it is probably justified to bring in a mold expert to perform mold inspection and testing in a building.
  2. [Mold] Source substitution: this approach to IAQ contaminants refers to selecting a less toxic material, such as low-VOC paints. IAQ problem source substitution may pertain to mold remediation in selection of encapsulants but otherwise it is less significant than source removal.
  3. [Mold] Source encapsulation: this approach to IAQ pollutant management, where the contaminant is mold, might include the use of encapsulant sprays or coatings to immobilize mold or dust particles that remain on surfaces after cleaning.

    Encapsulation is not usually a good substitute for mold removal. More subtle is the question of the priority of removing toxic or allergenic or pathogenic mold contamination suspected to be inside of a building cavity such as an enclosed wall or ceiling.

    Self-Encapsulated mold contamination, a term we invent for this discussion, refers to a building mold reservoir that appears to be enclosed in a wall, ceiling, or floor cavity such that one might suspect that the mold is not affecting building occupants.

    Watch out: these apparently "self encapsulated" mold problems in building cavities are often not as benign as we might wish. As the building environment varies in temperature, moisture, light, and air movement, a presumed "encapsulated" mold reservoir may indeed release problematic levels of mold spores or MVOCs into building air.

    However, in our opinion, while self-encapsulated mold reservoirs in a building should be removed and the cause of the mold growth should be found and corrected, if the self-encapsulated mold reservoir does not appear to be affecting the rest of the building, the remediation might be handled as a non-emergency.

    But don't wait to find and fix building leaks that may not only be causing hidden mold contamination but also building rot or other problems.

2. Local Exhaust of Contaminated or Moldy Indoor Air or of other indoor air pollutants

Local exhaust during mold cleanup is also a critical step in controlling the movement of moldy dust during a mold cleanup project in a building.

By using air handlers that in essence blow indoor air from the mold remediation work-space outdoors, we assure that air pressure inside the mold-contaminated area is lower than air pressure in nearby building areas.

This pressure difference can prevent cross-contamination of moldy dust and debris from the mold area into other building areas.

Emergency local exhaust in a mold contaminated building can be installed promptly on the discovery of a large problem mold reservoir using fans to blow indoor air from the moldy area and moldy odors (MVOCs) outdoors. This step is not, however, a substitute for cleaning and removing the problem mold.

Watch out: local exhaust is not an effective remedy for indoor mold contamination - the mold must be removed. And local exhaust can interfere with the safe operation of heating appliances by creating backdrafting


that in turn can cause dangerous, even fatal carbon monoxide hazards

Local exhaust can also cause unanticipated movement of other remote indoor air pollutants (mold, gases, or other problems) through various building areas.

Local exhaust is effective in removing "point sources" of indoor air pollutants such as temporary VOC contamination from indoor painting (PAINTS & COATINGS ODORS) or odors from kitchens and bathrooms (PLUMBING SYSTEM ODORS).

In other cases it is important to identify and fix the source of building odors (ODORS GASES SMELLS, DIAGNOSIS & CURE),

especially if potentially toxic or explosive gases (see HYDROGEN SULFIDE GAS and METHANE GAS SOURCES and SEWER GAS ODORS) are present.


3. Ventilation of the building to dilute contaminated indoor air

Ventilation uses fresh outdoor air to dilute polluted indoor air in buildings. While national and local building codes provide specifications for the amount of fresh air needed or recommended in buildings, ASHRAE and EPA standards typically give 15 cmf of fresh air per person as a benchmark.

Increased building fresh air ventilation is needed for special situations such as during painting or floor re-finishing.

At VENTILATION in BUILDINGS we provide in depth information about building intake, balanced, and exhaust fresh air ventilation systems.

4. Exposure control to reduce the impact of moldy or contaminated indoor air

Exposure control as a means of controlling the impact on people of contaminated indoor air refers to limiting the amount of time that people spend in suspect or known-contaminated areas. Actually all of the indoor air pollutant and mold contamination control strategies impact the level of exposure of building occupants.

Watch out: individual sensitivity to mold, MVOCs or other indoor pollutants varies widely, so even if some building occupants appear not to be bothered by indoor mold contamination, that same indoor mold level could be very serious for others.

At an audiology clinic we investigated the staff had no indoor mold complaint, even though they knew that extensive mold growth was visible over a suspended ceiling in the offices. But when an asthmatic client entered for a hearing test he experienced a very serious reaction to the indoor mold levels.

5. Air Cleaning / Filtration to reduce the impact of indoor mold or other air pollutants

Air cleaning or indoor air filtration(AIR FILTERS for HVAC SYSTEMS and CONTINUOUS BLOWER FAN OPERATION) is a useful strategy in general in buildings where it is desirable to reduce the level of indoor dust and in some cases with specialized filters, odors as well.

Watch out: air cleaners or purifiers (AIR CLEANER PURIFIER TYPES) are not a substitute for removing a problematic indoor mold reservoir, and portable air cleaners in general are not capable of effectively cleaning and making safe the air supply in a building.

6. Education of building owners and occupants to control indoor mold problems or other indoor air pollutants

Where a building has or might have a significant indoor mold contamination problem, building owners and managers as well as occupants benefit from knowing

The "MOLD ACTION GUIDE" contains sufficient information to address these questions. This website offers more in-depth articles on these and related environmental and indoor air quality topics.

How Should a Building Mold "Test" be Conducted?

Reader Question: does my mold test result indicate a bad problem? do I need a mold specialist?

We had a flood in our basement a month ago and before having any reconstruction done I wanted to make sure there was no mold present. I have a respiratory condition. The company that did the testing found mold present in one area and an elevated spore count in one area of the basement.

The mold identified was aspergillis penicillium and the advice was to get a company to get rid of it. The count for outside was 210 spores per m3 and in the basement 2600m3.

The basement was dry, but one area had a visible grey fuzz that was identified as mold. The main floor count was 110 spores per m3. I simply want to know how BAD the problem is and is it something that can be removed by a non specialist.

Do these numbers warrant professional intervention? How much would this cost, any idea? Your input would be appreciated. I think this website is very informative, and I would highly recommend it. Thanks,- N.M. 8/23/2013

Reply: what should your mold test consultant actually have done to provide useful information, and what should s/he report to you?

With respect I have to say I'm troubled that you paid someone to "test" your home for mold or perhaps better, "inspect" for mold contamination and then are left having to ask others to interpret and advise you on how to proceed. What the heck did your testing company take your money for if they're not going to actually try to be of use? More about actualy usable mold test and investigation reports can be read

Incidentally, "aspergillus penicillium" as your report stated, or Pen/Asp as many labs report, is a name used to describe the presence of either or both of two completely differnt mold genera/species - Aspergillus sp. or Penicillium sp. - a result that is offered when the lab has only undifferentiated spores that cannot be named more specifically.

Either of these mold families are common in outdoor air and are found indoors too, but when found indoors at high levels usually this indicates that further investigation is needed to find and remove the mold; The comparison of incompletely identified Pen/Asp spores found indoors with incompletely identified Pen/Asp spores found outdoors is somewhat nonsensical: we may be comparing counts completely different mold genera/species.

With that caveat and gripe stated and out of the way, your "count" shows that there is probably an indoor mold reservoir that needs to be found and removed - cleaning hard surfaces, disposing of stuff like drywall or insulation that can't be cleaned; then you want to know for sure that the cause of mold growth was properly identified and corrected as well. Details about common mold test report "mold levels" and test accuracy and precision are found at

And the work to clean up mold contamination needs to be done properly so as not to blow moldy dust elsewher, contaminating the home and leading to a new costly round of cleaning.

A "mold test" that just has someone stop by to grap an air, dust, or worse, culture sample to come up with some sort of "mold count" is, alone, not very helpful, and certainly not worth more than about $50. in my opinion. Such a mold test, especially if results are negative, are extremely unreliable. And even when a "mold test" such as yours is suggestive of a problem, you are left wondering

Watch out: by no means do I suggest that every building needs a costly mold investigation by a true expert. The article: MOLD / ENVIRONMENTAL EXPERT, HIRE ? can help you decide if conditions warrant bringing in someone who actually knows something and who will actually help you. I would not go back to yor first company again.

Small areas of mold, if that's all you've got, say less than 30 sqft of contiguous moldy material, are usually handled as a normal cleanup job without heroic efforts, For a small or DIY mold cleanup project see

Larger areas of mold contamination, or if a larger area is discovered in cleaning the small one, do indeed merit professional cleaning. When a professional mold cleanup job seems to be needed, these articles will be helpful

A proper "mold contamination inspection" inspection includes

But nobody can possibly make a confident, safe statement about just what mold remediation you need from an email alone nor can a simple mold test in air or on surfaces define the extent of mold contamination nor cleanup that may be needed at a building.

Helpful Articles Offering Detailed Advice on How to Find, Test, Clean up, Remove, & Prevent Indoor Mold Contamination

For advice concerning all other indoor and building-related environmental and health hazards

HIRE AN EXPERT - Do you need to hire a mold expert, bring in a mold remediator, hire a handyman, or clean up for yourself?

Photo of a wet moldy crawl space: We go to find mold reservoirs in locations where no one else wants-to enter.

Readers should see WHEN TO HIRE A MOLD EXPERT for details about how to decide when hiring a mold expert is justified and appropriate.

See MOLD INSPECTORS & MOLD TESTERS for a list of mold investigators whose work is familiar to us. Other mold investigators and test consultants may also be competent and qualified.

MOLD RELATED ILLNESS - Asthma, Allergies, Lung, Neurological, Other Complaints?

The following articles provide detailed information about mold-related illnesses.

PREVENT MOLD - How to Prevent Mold Growth and Avoid Mold Problems in Buildings

The following articles provide detailed information about how to prevent mold growth in buildings and in their mechanical systems.

MOLD DETECTION - Mold Identification Photos and Tips

These articles explain how to find and recognize mold in a building. The articles include mold recognition photos, methods of visual inspection for mold, and explanation of how to cut your mold investigation cost and trouble by learning to recognize stuff that is not mold at all. We also explain that not all black mold is harmful. Some is cosmetic only. Visual inspection can answer some of these questions without mold testing.

Photo of mold hidden behind wallpaper (C) Daniel Friedman

Photo of hard to see light colored mold on wall paneling (C) Daniel Friedman

MOLD TEST PROCEDURES - Valid and in-valid mold testing methods & protocols. Are some mold test kits junk science?

Please see MOLD SAMPLING METHODS in the Indoor Environment and in addition, the mold test critique articles listed just below.


Continue reading at ACCEPTABLE MOLD LEVEL or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

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MOLD CONTAMINATION IN BUILDINGS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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