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.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

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.

[Click to enlarge any image]

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 Series 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.

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.

MOLD CULTURES - Validity and Usefulness of Mold Cultures & Culture-Based Home Test Kits for mold

For a quick to understand overview of the validity and usefulness or perhaps not-usefulness of culture tests for mold, see Validity of Cultures (settlement plates or swabs) to find toxic mold in Buildings which is an overview and critique of using mold cultures, settlement plates, petri dishes, and cultured swab samples, and air sample testing limitations for determining what's in a Building, and which tests are useful in different situations.

For more thorough detail see SHORTCOMINGS of MOLD CULTURE TESTS which lists a number of detailed concerns about viable spore traps and culture media for Building problem detection

MOLD CLASSES, LEVELS - Mold Hazard levels, Mold Spore Count Validity, Interpreting Mold Counts, and Classes of Mold

Please see MOLD CLASSES, LEVELS for the full text article on this topic.

MOLD REPORTS - Mold and IAQ Investigation Reports

Robigus, Lord of Fungus - a brief history of the Legend of Wheat Rust Fungus

Uredinospores (C) Daniel FriedmanRobigus, the Roman God and Lord of Crop Fungi, is by legend the power who arranged that wheat rust, a crop destroying fungus, would plague humanity. This punishment was in retribution for the cruelty of a boy who set fire to straw he had tied to a foxes tail. Indeed, wheat rust leaves crops looking burned, and leaves as much as 40% of the crop destroyed. Robigus, a fertility god, protected crops against diseases.

At the Robigalia festival each April 25th, red-colored offerings (wine) were made to appease this god of the rust-red colored wheat rust fungus or wheat leaf rust a parasitic fungus, Puccinia recondita.

Rusts, or Uredinales, include Puccinia rusts that invade corn, cotton, mint, sugar cane, and wheat, also Melampsora - flax, Hemileia - coffee, Cronartium - pine, Uromyces - chickpea, bean, and many others. There are about 5000 species in this group.

Our lab photo (left) shows typical Urediniospores from an air sample where rust spores were frequent. (These are not wheat rust spores).

Wheat leaf rust causes small (1/32") reddish-brown pustules or blisters to appear on the surface of plant leaves.

The wheat leaf rust Puccinia recondita spores may also produce a reddish brown dust (mold spore powder).

Mature wheat leaf rust fungus pustules and their fungal spores may be dark brown or even black. Wheat leaf rust spores live only on live leaves but survive the winter on leaf fragments, periodically reaching epidemic proportions in the wheat crop.

Interestingly, the location of wheat rust on the plant can indicate its source: rust on upper plant leaves suggests that spores blew into the wheat field from a more distant location, while wheat rust pustules found on lower plant leaves indicate that the rust fungus over-wintered on leaves in the local field.

In addition to application of systemic wheat foliar fungicides such as Tilt, Quadris, and Mancozeb, some varieties of wheat are bred to resist this fungus, and experts note that resistant species are the best way to control wheat rust epidemics. More information about wheat leaf rust is at the Kansas State University Website.

Pileolaria_brevipes_rust (C) Daniel friedmanRust spores can be quite beautiful, belying the crop damage they may cause, as our lab photo of Pileolaria brevipes (a rust spore found in an air sample we collected in San Diego, CA) shows at left.

While focuses attention on building and indoor environmental concerns, the history and forensic work on Puccinia recondita is so important to the world's wheat crop and serves so well as an example of good investigative work that we have included this expanding topical section.

TECHNICAL PROCEDURES - Technical & Laboratory Procedures

Good Laboratory and Microscope Procedures are critical in making sense of field samples. Competent, trained, experienced aerobiologists, mycologists, and microbiologists can identify sample contents with good accuracy.

Depending on the experience of the laboratory, it is also possible to interpret the meaning of the sample for the Building and its occupants.

Laboratory professionals who have also performed the field inspection can make useful extrapolations from lab results. Hasty work by disinterested parties may be less useful for Building occupants and owners.

Please see TECHNICAL & LAB PROCEDURES for the full text article on this topic.

OTHER IAQ CONCERNS - Other Indoor Air Quality Concerns

See ENVIRONMENTAL HAZARD MAIN WEB PAGE: Environmental Hazard Detection, Testing, Repair, Illness, Symptoms, & Prevention in Buildings - research and "how to" articles

Mold Testing: Examining the Validity of Current Indoor Mold Sampling Techniques

The complete and most current version of this paper is found at MOLD TESTING METHOD VALIDITY. Excerpts are below.

This paper presents a summary and critique of some popular methods used to examine indoor air quality to test for presence or absence of problematic levels of toxic or allergenic mold or other bioaerosols. we will describe and critique specific "testing" or "sampling" methods used to "test" Buildings for mold in the course of a Building investigation.

The appropriateness of testing at all is discussed on this and other pages at our website. our website includes more broad discussions of the overall approach to Building investigation, as do many expert references cited at that web. For a more comprehensive collection information about mold test methods see

The full-text version of this presentation is at - © 2017 - 2005 Daniel Friedman. An illustrated power-point version of this document is at - © 2017 - 2005 Daniel Friedman, but involves larger files of images and data - if you are viewing this document from a low-speed line you should stick with the text version.

Watch Out: interpret all quantitative data with great caution. Individual samples of particles in air show tremendous variation from minute to minute, making "ok" test results a thing to view with care. In situations of particular risk additional or periodic testing should be considered.

If you think you need to hire someone, see WHEN to HIRE a PROFESSIONAL for more detailed help in deciding when and how to proceed. Also see CAN MOLD MAKE YOU SICK?


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

Or seeMOLD CONTAMINATION in BUILDINGS, FAQs-2 - more-recent Q&A posted at this page, and also MOLD CONTAMINATION in BUILDINGS, FAQs - older mold contamination questions & answers posted here.




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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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