Question? Just ask us!
Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
InspectAPedia ® Home
ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY
MOLD: A COMPLETE GUIDE TO MOLD
MOLD ACTION GUIDE - WHAT TO DO ABOUT MOLD
MOLD APPEARANCE - WHAT MOLD LOOKS LIKE
MOLD CLEANERS - WHAT TO USE
MOLD CLEANUP GUIDE- HOW TO GET RID OF MOLD
MOLD CLEARANCE INSPECTIONS
MOLD COUNT NUMBER GUIDE
MOLD CONSULTANTS / INSPECTORS
MOLD CULTURE TEST KIT VALIDITY
MOLD DETECTION & INSPECTION GUIDE
MOLD or INDOOR AIR EMERGENCY RESPONSE
MOLD / ENVIRONMENTAL EXPERT, HIRE ?
MOLD LEVEL IN AIR, VALIDITY
MOLD ODORS, MUSTY SMELLS
MOLD PREVENTION GUIDE
MOLD RELATED ILLNESS GUIDE
MOLD SAFETY WARNINGS
MOLD SPRAYS, SEALANTS, PAINTS
MOLD TEST KITS
MOLD TESTING METHOD VALIDITY
Mold Standards for Exposure & Testing:
This InspectAPedia technical article describes various current & proposed mold standards as well as the very substantial shortcomings in any mold exposure standard whatsoever.
Here we also explain reasons for substantial variation in and interpretation of the meaning of airborne mold spore counts, moldy surface density, and other measures of the exposure level of allergenic, infectious, and levels of toxic mold in buildings. At what level is allergenic or toxic mold considered a problem in buildings? How do we obtain an accurate and meaningful measurement of mold exposure indoors?
Green links show where you are. © Copyright 2015 InspectApedia.com, All Rights Reserved.
Warning: fungal spore counts in indoor air, whether "viable" or "non-viable" counts, as well as swab and culture methods to identify just what mold is present in a building are questionable methods to characterize the presence or absence of a mold problem indoors.
From experience carefully inspecting many buildings for mold problems and simultaneously collecting many types of field samples and examining them in our lab, our view is that anyone who makes one or a few indoor air measurements or relies on culture plates or swabs to "characterize" the mold level and mold species in a building is risking being way off target, particularly if the "test results" show low numbers.
See ACCURACY OF AIRBORNE MOLD SPORE COUNTS for more details about these issues. That said, here is a sampling of some indoor air mold spore exposure level criteria and comments
1. Baxter et als: Mold contamination is considered present in a building when the total mold spore concentration per cubic meter is above 10,000. Our own field and lab experience confirms this view. However in special cases, even low quantitative levels of certain particles or particle types (such as Pen/Asp spore chains in an un-treated building) may be diagnostic and may indicate a hidden mold reservoir that at least merits further investigation.
2. The National Allergy Bureau, reporting the NAB SCALE (National Allergy Bureau) of mold and pollen counts, considers mold counts in outdoor air of 0-6499 spores per cubic meter of air as low, to 6500 to 12,999 spores per cubic meter of air as moderate, to 13,000 to 49,999 spores per cubic meter of air as high, and above 50,000 as very high. At "high" levels most individuals with any sensitivity will experience
symptoms. AAAAI also provides absent, low, moderate, high, and very-high level level definitions for grass, tree, and weed pollen grains counted per cubic meter of outdoor air.
3. The University of Minnesota data presents this table for mold levels expressed in colony forming units per gram. WARNING: mold spores may be not viable (dead), wrong culture media may be used, or one species can overgrow another, etc. - so don't produce any colonies, but may be toxic if inhaled (such as some species of Penicillium). So we would not rely on culture data. But here it is:
Colony Forming Units/gram - cultured mold samples as indicators of mold level in buildings
WARNING: about interpreting mold cultures: this is a very very inaccurate method for screening buildings for the level of mold contamination for many reasons, including that only 10% of all molds will grow on any culture under any condition. So this approach begins as 90% "wrong".
Other mold level variables include the differences in settlement rate out of air as a function of particle size and weight, proximity to a mold contamination reservoir, and the problem that a serious toxic mold may be overgrown (if it grows at all) in the culture by a second mold species which hides the first one. See INDOOR AIR QUALITY METHODS COMPARED for details of these issues.
4.The American Conference of Government Industrial Hygienists (ACGIH) stated (Harriet Burge et. al) stated in 1987 that indoor mold levels are generally less than 1/3 the outdoor level and that when indoor mold is at more than this level remedial action should betaken to find the source of the elevated counts and to clean it up.
WARNING: this is an inaccurate and unreliable method for screening buildings for mold for many reasons, including:
See INDOOR AIR QUALITY METHODS COMPARED for details of these issues.
5. Other proposals for Mold Exposure Standards have included a limit of 500 CFU/ of mold spores per cubic meter of air in winter indoors in sub arctic climates (Reponen et al.1990). CFU means "colony forming units" of mold.
At MOLD CULTURE PLATE TEST ERRORS we have cited the range of errors and limitations of using cultures to check for viable mold, and we point out that depending on the particular mold genera and species present in a building, even non-viable mold may be allergenic or toxic. That is why experts in mold testing and remediation advise that the object is to remove mold or clean up mold in a moldy indoor environment, rather than attempting to "kill" mold indoors.
Also see INDOOR AIR QUALITY METHODS COMPARED for details of these issues.
Single number "mold levels" are very unreliable as a measure of health risk in buildings for several reasons including at least the following:
Particle levels vary widely over short time periods: The actual level of indoor particles in air varies by several orders of magnitude over very short few-minute intervals, making reliance on any single measurement questionable, particularly if the measurement does not show evidence of a problem.
The absolute level of airborne particles in buildings varies enormously, possibly by a factor of hundreds to thousands, over intervals as short as a few minutes. Simple mechanical disturbance like turning on or off a fan can completely change individual measurement results. Short term measurements are therefore inaccurate and even longer term measurements are inaccurate if they do not consider the in-use variations in dust disturbance in a building.
Human sensitivity to mold varies: Individual susceptibility to mold/mycotoxin/aflatoxin-related or allergy-related illness varies widely and human exposure is complex because people move among a variety of environments
Finally, because of wide variation in individual human reaction and risk to mold, variation in allergenicity, pathogenicity, and toxicity among mold genera and individual species, and even additional variation in these levels depending on specific environmental conditions such as the substrate upon which a mold is growing (its food), quantitative risk-levels are better used as an overall indication of building cleanliness before and after a mold cleanup, and not as an absolute level of risk to building occupants.
There is very wide variance among the toxicity of individual mold species, ranging from none to probably highly toxic, pathogenic, or even carcinogenic
Mold Spore size varies widely from less than 1 u to over 200u, so a large spore contains potentially more harmful material than a small spore of the same "toxicity," making a "count" that does not identify the particle and particle size ambiguous
Mold spore toxicity may vary, even within an individual species, depending on what substrate the species is growing on in a particular instance, e.g. wood vs. drywall.
These mold spores vary in significance: procedures that use cultures to identify "viable" spores may omit high levels of non-viable spores which nonetheless remain highly toxic. Methods that rely on culturing have a high risk of identifying a mold which is present but is not the dominant or even the most problematic mold in the building. For more details see Mold Spore Counts: are indoor fungal spore counts valid?for further explanation.
For the standards and references below, numbers are spores per cubic meter of air and do not consider individual or viable/non-viable or genera-species specific levels. There is a serious limitation of the standards since the spores of different genera and species vary widely in total size, mass, and toxicity.
The level of airborne particles indoors varies enormously, by orders of magnitude, from moment to moment, making the strict interpretation of any "indoor air mold test" unreliable, as we discuss at ACCURACY OF AIRBORNE MOLD SPORE COUNTS. -DF
Note: Previous data provided at this web article had been obtained from a presentation by J.R. Tucker, EMS-sales, who presented data at the NC/SC Environmental Information Association 2005 Conference, Myrtle Beach, SC citing mold exposure standards from Brazil, mold exposure standards for Czechoslovakia, Mold exposure guidelines for Finland, Mold exposure standards set by the Nordic Council, mold standards cited by the World Health Organization WHO, and mold exposure standards for the Netherlands and lastly, mold exposure standards for Poland. Those figures were quoted in this article from the material provided at that conference. Mold exposure standard numbers were expressed spores per cubic meter of air and did not consider individual or viable/non-viable or genera-species specific levels. We have removed those data points at the request of Dr. Robert Brandys who informed us that he was and remains the original author.
Mycotoxins are produced by some common molds found in buildings, including Aspergillus, Penicillium, Fusarium, Stachybotrys, and even Alternaria. Common classification groups of mycotoxins include aflatoxins, fumonisins, trichothecens, and ergot alkaloids. Arora has pointed out that the following conditions are necessary for mycotoxins to affect humans:
Human Health Complaints on Exposure to Problematic Mold, possibly including Mycotoxins
Given even these stringent criteria, field investigations of moldy buildings that we have conducted from 1986 to present, included both human building occupants and in some cases pets who appeared exhibit complaints or symptoms consistent with mycotoxin exposure. Some of these clients and their physicians confirmed that exposure by appropriate medical tests.
Sheep Circling Disease and Toxic Mold Exposure
A fellow aerobiologist who also has experience raising sheep, Larry Syzdek (PAAA member) informed us of a mold-related illness well known to occur in sheep which Syzdek explained has occurred in his experience in sheep exposed to moldy straw, called in lay terms, "sheep circling disease" (Listeriosis, however Listeria moncytogenes is the specific bacterium - not a mold - known to cause listeriosis, a disease which can affect both other animals and also humans, particularly pregnant women who are 20 times more likely than other healthy adults to get listeriosis).
The author of this web article, (Friedman) has described field observations of dogs appearing to exhibit strange behavior (running in circles, falling down, disorientation, and occasional uncharacteristic aggressive behavior, and in one case, fatal internal bleeding after severe exposure to S. chartarum during a building demolition. These animals were pets of clients whose homes were severely mold-contaminated.
With Syzdek, we have speculated on the possibility that other animals than sheep may be similar affected by exposure to some indoor molds and may be exhibiting behavior similar to that caused by Listgeriosis though the etiology of this disease is suspected to be different.
At MOLD RELATED ILLNESS GUIDE or in the FAQs section of that article we include a 2014 report from a Salem Oregon family who describe drunken behaviour of dogs after the dogs spend time outdoors.
These hypothetical remarks presented here intend to solicit additional field reports and data, possibly in support of future controlled studies. Readers should not assume that we have drawn conclusions from the suggestive anecdotal data currently at hand.
Some species specific acceptable levels have been addressed and vary considerably by species, environmental conditions, and proponent.
REFERENCE:A number of resources cited here are reviewed more carefully in "Comparisons of seasonal fungal prevalence in indoor and outdoor air and in house dusts of dwellings in one Northeast American County," Ping Ren,
Thomas M. Jaunkun and Brian P. Leaderer, Division of Environmental Health Sciences, Department of Epidemiology and Public Health, Yale University School
of Medicine, New Haven Ct. and appearing in the Journal of Exposure Analysis and Environmental Epidemiology (1999) 9, 560-568.
See references below for important additional information such as mold testing, cleanup and mold remediation guideline resources.
According to A.S. Arora: Stachybotrys chartarum strain s72 contains 1.0x10-4 nanograms of satratoxin H per spore. 10 billion spores of s72 S. chartarum must be present in a single cubic meter of air to produce one milligram of satratoxin H per meter of air. Dr. Arora continues: "... it was calculated that a no-effect dose [in rats] corresponds to a 24-hour exposure to 3 billion spores per cubic meter of air for an infant [human], 9.5 billions spores per meter for school-age children, and 22 billion spores per cubic meter for adults."
Dr. Arora did not expand his discussion to address any potential cumulative toxicity of longer term exposure to lower levels of mycotoxins in buildings.
This "toxic black mold," Stachybotrys chartarum, infamous thanks to media attention, is not designed for airborne transmission, being large and sticky. The Stachybotrys family of molds appear to have evolved to be spread by sticking to the cow's foot as it walked through moldy straw.
Indeed we often find S. chartarum mold spores present in air samples when a dense colony of such mold is being mechanically disturbed, such as during demolition. But we have never seen it in air anywhere close to the levels cited as the "no-effect dose." We believe that we've been barking up the wrong mold-tree, and that one would be smarter to look in buildings for the Penicillium and Aspergillus families which spread throughout a building easily by airborne transmission
REFERENCE: Content of this section paraphrased and others quoted from a guest column, "Understanding the Health Effects of Mold," by Dr. Ajit S. Arora, MD, PhD, appearing in AIHA's magazine "The Synergist," September 2003, in the AIH Diplomate section, Pages vi-vii. Dr. Arora is a forensic medical examiner and medical toxicologist in Los Angeles. See partheniamedical.com.
"Clean" residential buildings are typically 230/m3 +/- 630.
We usually find only trace levels of Penicillium/Aspergillus indoors in residential buildings and offices, so counts even close to the "clean" level may make further investigation a reasonable course of action, particularly where the building houses occupants have complaints possibly due to mold, or occupants who may be at extra risk.
Holmberg (1987) associated Aspergillus spore levels over 50 CFU / cubic meter with sick building syndrome. We comment elsewhere that depending on culturing mold in buildings is unreliable since toxic or allergenic particles may be present but may be of a species or genera which either does not grow on a culture medium, or which is overgrown by something else on the medium.
Further, relying on settlement plates to culture mold produces quantitatively skewed results since different particles settle out of air at different rates, confounding an estimate of their numbers. Anderson™ multi-stage samplers which develop culturable samples attempt to overcome the particle size problem.(C)Trap DJ Friedman
Aspergillus sp. may be the most common and serious airborne mold problems in buildings: Opinion: from the author (DJ Friedman) based on extensive field investigations and laboratory work, we suspect that several species of Aspergillus are probably the most common and widespread problem mold found indoors in buildings.
These spores are small, easily airborne, grow on a variety of surface materials, and move readily throughout a building almost like a gas (due to their small size) riding on building convection currents and remaining airborne for long periods of time.
Continue reading at MOLD TEST vs. PROBLEM DIAGNOSIS
Green link shows where you are in this article series.
Frequently Asked Questions (FAQs)
Question: can long term mold exposure affect the immune system?
I have a friend who has been working as a kitchen manager at a nearby college for over twentyfive years. Six years ago she came down ill with something no doctor could diagnose. She was actually off on sick leave for just over a year before she could sufficiantly recover to go back to work. Every symptom named in Mold sickness were present. Now after being back at work for a couple years, same job, she is again crashing. Same symptoms. A couple months ago, there was a wall torn out to fix a leak behind the steamer that had been there for years.
It came down the wall from an upstairs bathroom and it was a small leak that was tolerated and cleaned up daily. When finally the problem was fixed the walls inside the kitchen was evey color imaginable and a large portion was torn out and replaced. Mold remediation was not called in and a warning was given to the staff present at the time, that nothing could be said for surely the college would be shut down and extensive work would have to be done. She decided to retire since she it too tired to mvoe these days. I went with her today to clean out her desk.
I have had chemical poisioning year ago and If there is any kind of chemical reaction going on, including mold, I immediatly fell the mold spores light, as if it were on my skin. It feels like a tiny pinprick and begins immediatly to itch and soon spread all over my body. I break out in red welts. I sat in her office today while she emptied her desk and locker. By the time we got back to the vehicle to drive away, I realized without a doubt that I had been in the presence of airborn mold spores. By the time we drove the twenty minutes home, I had to strip, take a shower, wash my cloths with bleach and take a benedryl. I think she has had long term exposure to the mold and therefore, her immune system is highly effected. What do you think? - Chaplain CJ Echols
It sounds as if you and your friend needs to consult a doctor who is expert in environmental medicine for expert help in both diagnosis and treatment. Ask the doc what sorts of contaminants or exposures are most likely to cause or aggravate the complaints.
Question: Accurate mold counts? How do we know if our school is safe?
So reading this article it seems that accurately determining mold counts is very tough. So how do we know if our school is safe? We do know that there has been a lot of black mold found behind walls and other places. And that indoor mold counts in some classrooms is about 5000 count per cubic meter. But what do we do now? The administration just says 'It's fine.' - My school has mold
Reader follow-up comment:
Yes.. I agree.. the 'All if fine' routine from admin and the superintendent is a bit worrisome. But no one seems to be doing anything about it. Any idea who or what department or agency I should call to look into this? Thanks!!!
MOLD / ENVIRONMENTAL EXPERT, HIRE ? will give you some help in deciding if it's appropriate to bring in an independent expert; if so, you'll then have a credible third party who can provide information to your school administrators. There may be legal or procedural issues about who has authority to bring in someone - be sure you've resolved those before hiring anyone.
Question: how to interpret airborne mold count levelsk, 1833 Aspergillus/Penicillium outdoors & 8553 indoors?
My workplace has a mold problem and a air sample analysis was done in August. I just got a copy of it as my doctor requested it. Question is - report shows outside level of 1833 or 4.2% Aspergillus/Penicillium and inside count of 8553 or 97.0% per cubic meter of Aspergillus/Penicillium. What do these numbers suggest? All 6 employees are having health issues.
Question: Are there health risks to building occupants during duct cleaning & ceiling replacement?
My company is having the building cleaned, the ductwork replaced and ceiling tiles replaced. They have been telling us that there is no health risk to us working in the building. The report that I was given really doesn't say how bad the air quality is. I am just a small fish at the bottom of a very large corporate pool and told I have a job to do. - Anonymous
There may be OSHA or other regulations that should guide cleaning or renovation work in your building, and if hazardous materials are present that is surely the case. More generally, if the cleaners in your building are taking steps to control the release of dust during the work, such as setting up containment, using negative air machines, or HEPA vaccuming, or if the work is being performed in areas whose air and dust does not readily enter the work area, the risk to occupants is of course reduced.
Question: Following a death due to mold exposure in a building, how long can the spores live after the source has been removed?
How long can the spores live after the source has been removed? How serious is the contamination of personal items in the home and how long after the source is removed, are they safe if ever? More specifically, we are dealing with exposure to a home 4 years after a death occured in the home due to mycotoxicosis of asperigillus and stachybotrys. The original source of the mold was not in this home, but rather at a work place.
A year after the death, family members and a caregiver came down with symptoms and now test positive for the same toxins the family member died of. They claim the house is cross contaminated and abandoned it. 3 years later, we were hired to clean out the home and just found out this information. 3 years ago at the time of the abandonment, the house was tested and found to be 16 times the normal levels of the mold spores.
Unknowingly, we brought items into our home, donated items to friends and charity, and cleaned the entire home with out face masks or respirators. A 3 year old child and pregnant woman were also exposed. Should we be concerned? - Tracey
Reply: dead mold spores may still be a problem; but small or sub-acute levels of moldy dust without an actual mold growth reservoir are not normally a problem
If you continue to be concerned about having imported moldy dust into your home you should take these steps to reduce that concern:
Make sure that your own home does not have its own leaks, moisture problems, and hidden or visible mold growth reservoir, independent of any dust that you may have imported.
HEPA Vacuum and wipe dusty surfaces in the home
Wash or dry clean clothing that may have been exposed to high levels of moldy dust or other problem dust contamination
Change air filters in your heating or air conditionong system
See MOLD / ENVIRONMENTAL EXPERT, HIRE ? for more advice on how to decide if it is appropriate and justified to bring in an expert to survey the building for problem mold contamination or other IAQ worries.
Question: can you refer me to a mold inspector in Germany?
Can you recommend mold inspectors in Kaiserslautern Germany? I am in the US Military and recently moved here and think I have mold in my rental house.
Reply: sources of mold experts and advice on choosing one
Brian, you should contact your base medical and health officers for advice on inspecting your home for health worries, and see MOLD / ENVIRONMENTAL EXPERT, HIRE ?
Moldy odors are produced by some, not all, species of mold, and even then, not in all conditions. The production of MVOCs (mold volatile organic compounds) that you smell in air depends on the genera/species of mold, the surface on which it is growing, and growth conditions such as moisture, temperature, light exposure. And similarly, mold spore release is a natural event that occurs depending on growing conditions as well as on mechanical disturbance such as during demolition or cleaning.
Question: Can you Interpret my Mold Test Report?
My Mother had some testing done for mold in her home. I was hoping that you could shed some light on this. This threw her into panic mode. She has had some sinus problems which could be related to this mold in home. I am reaching out to you so that we know how quickly this needs to be remediated. I have attached a Mold test report [edited to remove personal information - ed.] that I was hoping you could decipher or point me in the right direction of a company that I could reach out to here in Wyoming, Michigan where my Mother’s home is located.
I believe she does have some moisture problems as she has some peeling paint in most rooms of the main level. For years she has worried about the insulation in the attic but just too busy to get to the source of the problem. Thanks - A.R.
We took a look at your mold test report and note that your mold investigator through visual inspection and lab report concluded that professional mold cleaning is needed at your home. As we have not seen your property much less inspected it, in my opinion the person whom you paid to examine the home should be the first one in line to answer your questions about how to proceed. If s/he does not provide the service of explaining what was found and what you need to do about it, we might wonder what you paid for. Certainly in our opinion it would be a unconscionable to have to hire a second person just to explain what the first one said.
We agree with the approach of answering a mold remediation need question through a combined building inspection for visual evidence of the location and extent of mold contmaination, an interview with building occupants to estanblish the history ofthe home and possible occupant health concerns, limited testing to confirm that the mold seen is not just "cosmetic" is appropriate in some cases, and the combination of the experience of the inspector and lab results with the application of general mold level standards described by a reasonable and non-quantitative industry standard IICRC S520: Standard and Reference Guide for Professional Mold Remediation 
Watch out: you 'll want to be sure that the inspection of the home was thorough and that it identified both all areas that need mold remediation, the extent of remediation needed, and the causes of mold growth that need to be corrected. Without that level of information, in other words, a professional mold remediation plan, not just a "test report", you are at risk of wasting money by doing an incomplete job.
Question: Why are there no mold standards for the workplace?
Would you be able to help me/us?
Thanks again for getting back to me so quickly. - K.O.
Reply: Giving any single number for allowable mold exposure as a "standard" borders on junk science
Thank you for the interesting question - it helps us realize where we need to work on making our text more clear or more complete. A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem including addressing the question of whether or not there is in fact an indoor environmental hazard in your workplace.
Your statement that "mold was found..." itself is not diagnostic - I can find some mold in just about any building, new or old, anywhere in the world. Whether or not that constitutes a health risk depends mostly on the size of the mold contamination, also on how mold spores may become airborne and move through the building, and of course the genera/species of the dominant mold present - ranging from harmless cosmetic to seriously harmful.
I am also interested in your posing of the question " why is there no standards for mold in the workplace?" Often people will pose a question in a manner that presumes a-priori something that is simply not true - a silly example is the old saw of a legal question "Are you still beating your wife?" which presumes the individual ever beat his wife at all in the first place.
Actually there are dozens of attempts at "mold standards", both quantitative (questionable as I explain below) and qualitative (sensible as I explain in the article above) as you can see in the REFERENCES section of this article. That said, here are some things to consider in answering your presumptive question.
Take a look at MOLD / ENVIRONMENTAL EXPERT, HIRE ? for criteria that help decide if hiring an expert for a building is needed. Basically, if you see more than 30 sqft. of non-cosmetic mold indoors in a building (a few indoor molds are cosmetic only) then professional mold remediation is in order, period, and your building management would be mistaken to conclude otherewise. For cases where a large problem mold reservoir is not immediately visible and obvious, this article could be most helpful to you in deciding if there is reason to believe your workplace has conditions that make further, expert investigation appropriate.
Why single number mold standards are not accurate nor very useful
Mold "standards" that give an acceptable or unacceptable number of spores are really close to nonsense except at such very high levels as to be both unambiguous and not useful for less obvious mold contamination problems. In other words, at very high levels of problematic spores there is no argument that there is a problem to be found and removed. But that sledgehammer approach is not useful.
There are 1.5 million species that vary in toxicity to about 3 million levels if one adds the effects on toxicity of the substrate on which mold is growing. You'd need standards for each mold species by type, weight, growing conditions. The health effects of inhaling a specific genera/species of spore are so widespread, that a single numeric standard would just be junk science. Add to that the enormous variation in the "exposure level" found by different approaches to testing and the impact of varying building conditions, air movement, temperature, occupancy etc. looking for a standard is waiting for Godot.
Add to that factor a wide range of human or other animal response to mold exposure and a standard becomes still more difficult. I've instrumented some clients who responded with extreme distress to very low levels of airborne Aspergillus sp. (less than 300 spores/M3 of air) for example - an airborne mold level well below most accepted opinions of "what level of mold describes a contaminated building?"
Even the standard of comparing indoor to outdoor spore levels is highly questionable - since we can and usually are comparing numbers of completely different molds - an apples to oranges comparison.
However it is possible to combine an expert and complete outdoor and indoor and mechanicals system building inspection, interviews with building occupants, and some testing to guide a decision on what cleanup may be needed in a building. An experienced building diagnostician will consider some very general rules that help point to the presence of absence of a problematic indoor mold reservoir that needs to be found and removed and its cause corrected. "Testing" without a thorough inspection and interview is frankly not reliable.
What should be the approach to evaluating a mold-suspect building?
What is needed is an approach to deciding if there is an actionable problem in a building where obvious hazards (such as more than 30 sqft of problematic mold contamination) are not immediately apparent. And the conditions of exposure matter too. A worker whose job requires spending hours a day in a moldy automobile such as the one illustrated above could be exposed to serious hazards even when the total square feet of moldy material could be as small as just the interior of the vehicle air conditioning system. Details of moldy automobile hazards are at CAR MOLD CONTAMINATION
References to some helpful articles on mold standards, testing, expertise and need for an investigation
Please keep me posted on how things progress, and send along photos if you can. Such added details can help us understand what's happening and often permit some useful further comment. What we both learn may help me help someone else.
Question: what are safe and reasonable airborne mold counts for a home?
to editor Hi, I have been trying to find a source that lists what are considered to be safe and reasonable mold airborne counts for a home. Do you have this or can you direct me to a resource. Appreciate your help. - P.P. 5/17/2013
The third article points out that airborne mold counts are close to junk science because of the range of variability that encompasses several orders of magnitude.
Furthermore, since among the 1.5 million or so mold genera/species there is wide variation in particle size, probability of growing as an indoor mold, and toxicity, it is rather unreliable to consider only "mold count" without knowing something about what mold is actually present in the building as well as what molds are being detected in a test.
Let me know if any of that material is unclear or confusing and I'll do my best to help further.
Question: how to interpret an indoor mold air test and inspection that found no actionable contamination
I saw your website and it is very informative. I work in a library that I believe has mold due to water leaks, although there are no outward signs of mold. An air quality test was recently done and it showed some fungi spores such as Bipolaris and Cladosporium, but the outside air quality was shown to be much worse and I do not see how that is possible.
A comparison was made between the outdoor and indoor air and their conclusion was that "The bioaerosol results in [Anonymous] Library for total fungal spores did not identify an amplification or biodiversity of fungi between the indoor and outside sample."
No recommendation was made because I assume they feel that the indoor air is a minor issue when compared to the outdoor air. I have been having high blood pressure when I am in the building, but my blood pressure goes down to a normal level when I am outside, so I do not see how the outside air could be much worse than the inside air according to the test results. If I sent you a copy of the results via email, would you be willing to look at it and to see if this test looks legitimate? - Anonymous [data on file] 1/22/2014
Send me the report and I can comment. Keep in mind no remote analysis is a substitute for an onsite expert. I will take an initial look and comment pro bono. ...
[Reader provided a copy of an indoor IAQ inspection and test reports provided by an industrial hygienist. The hygienist performed a visual inspection, tested CO2 levels, and performed some air tests for mold. - document on file]
The details of the tests and lab report do not find evidence of an indoor mold contamination problem.
None of the species found in the actual "test" included the more problematic indoor spores that are most common in buildings where there is a serious mold contamination issue - such as in the Aspergillus group (highly airborne, small particles, breathed deeply into lungs, pathogenic or toxic) nor of the mycotoxin group such as Stachybotrys chartarum that is often found on wet drywall.
While the hygienist cites that there are no mold exposure standards, that is not quite the case. While I argue vigorously that a simple quantitative standard for mold exposure would be junk science (individual mold spores vary enormously in size, toxicity, airborne or other exposure pathways, so we would need hundreds of standards), nevertheless, experts have shown that there are general indoor mold levels that strongly indicate that a building has been subject to leaks and / or that there is probably an actionable (that is large) mold reservoir in the building. See MOLD STANDARDS for details.
And even when indoor mold test counts are low, on occasion one may find subtle clues that mean one could infer by looking at mold genera/species found indoors (which certainly were not matched to the outdoor spore mix) provide a very weak or low-level suggestion of water intrusion or leakage - that is, we see some mold growth that might be associated with water leaks.
The risk in any air test is that the airborne spore level can vary by several orders of magnitude depending on how the test is conducted. So absence of evidence of a mold problem when we rely principally on an air test is *not* proof that no problem is present.
But absence of such evidence, when combined with an expert inspection of the building for visual clues suggesting an actionable risk of a hidden problem reservoir (such as mold contamination in a ceiling or wall cavity) can add up to a conclusion that the expert could not find any justification for more invasive or extensive inspection steps.
I cannot comment on how expert the visual inspection was at your building. The reliability of that step depends largely on the particular experience and building-science knowledge of the inspector.
I can comment that comparing indoor air with outdoor air, while a very widely used practice, is rarely actually useful. Too often the genera/species are so different that simply comparing "spore counts" is nonsense - as comparing apples and oranges. The hygienist's own report makes this same pont.
I can add that sometimes, even very low levels of certain problematic mold spores in an indoor sample (such as Aspergillus spores in chains) can be detected by an astute lab technician and interpreted by an astute investigator as reason to look further for a building problem. At InspectApedia.com we have published a series of articles about these sources of error or of discovery should be considered by hygienists or other professionals who inspect or "test" buildings for mold or other similar contaminants. Two you may want to read are
The first article introduces the huge variation in airborne particle levels from minute to minute in a building as well as other sources of error that can overwhelm mold test accuracy.
The second article is interesting because a careful read of a typical mold-in-air test will show that sometimes data is being given where only a single mold spore of a given genera/species was actually detected. At that excruciatingly small count level one should not get excited about the translation into percentages. For example if indoor air contains "25% of toxic mold type X" and then we read that only four spores were detected in the whole sample, and one of these was type X, then such numbers are of little import. The devil is in these details.
In sum, nothing in the report you provided points toward an actionable indoor mold contamination issue nor documents a basis for more invasive further inspection or testing. That's not to say that the building is guaranteed "problem free" but it is reasonable to opine that an expert has examined the building and found no evidence that justifies further such action. For a more thoughtful look at how we decide when expert building investigation is probably warranted, see MOLD / ENVIRONMENTAL EXPERT, HIRE ?
If you are still convinced by your own experience that the building is responsible for personal health complaints then you will want to confer with your doctor and document his/her opinion, or that of a referred expert in environmental medicine, that your complaints are environment-related, caused, or aggravated.
For example, your doctor might cite other reasons for elevated blood pressure (your complaint) than an environmental one. Mold contamination itself is not usually blamed for high blood pressure, but in my opinion stress, including environmental stresses or even simple anxiety could be relevant factors.
If that conclusion is indeed reached, then next would be an examination of all environments where you spend the majority of your time, to see what can be found, if anything, that should be addressed.
Finally, I recommend caution against becoming a victim of a "capture error" - that is, don't let a specific fear that has come to mind (mold contamination) prevent you from looking more thoughtfully and broadly, and with medical advice, for the cause and thus recommended actions around a medical or health complaint.
Question: leave the moldy house alone or try to figure it out
(Feb 7, 2012) dee said:
our air test on a house we did inspection on shows 1080 count per cubic meter in basement with 81 in the upper level. i also had a severe burning in my chest/throat with congestion for 24 hours after having been there for the hour or so of inspection. never experienced anything like that before although I've always picked up on musty smells and gotten some congestion from them. we are thinking that it is better to leave this house alone than to try to figure out what could be done to resolve any concern because we don't own the house and we can't locate the problem.
sorry, that was of Asp/Penn I was refering to...
I don't know enough about the actual risk level in your home (from mold) - the test data is not by itself very helpful and may be inaccurate. But keep in mind that individual reaction to mold or MVOC or mycotoxin varies widely and that protracted exposure can increase someone's sensitivity.
Question: due diligence laws for commercial property owners and mold?
(Feb 27, 2012) Ryan R said:
What are the laws in Michigan and New York regarding due diligence of commercial property owners where a franchisee is in a space? Specifically, if a franchise restaurant has mold in its location, are there laws regarding notification and removal of mould by the property owner, or is it left to the franchisee? If so, what are these pieces of legislation, and where can they be found?
Let us know what your lawyer says about this question.
Question: moldy refrigerator drip pan and other building leaks - I'm getting sick
(Mar 11, 2012) email@example.com said:
Hi. I have lived in a condo for 4 years I have been renting, After the second year, i was vacuuming under the built in refrigerator and noticed the drip pan, I pulled it out and was full to top with moldy water of all colors. I cleaned it up put back with baking soda in pan and thought nothing of it. I had slowly been getting sicker with odd things, breathing, wheezing, numbness in left let, odd large blotchy spot on right shin, horrible itching I have Hep C and docs thought it was just that although my tests were all normal, eat well etc. last month had a sudden infestation of something biting, found evidence of carpet beetles.
Then when running AC which is in ceiling through a panel in bathroom, it was pouring water. Turned off and found the area covered in black looking mold, owner had test done, air levels came back moderate but no significance in air levels from inside to out. He had a window open in living room, He also had bathroom fan on blowing to outside front door where he did outside test. I had my own done by certified specialist. he asked did he close all windows fans etc, mine asked me to have all windows fans closed prior to arrival. my tests came back 47,000 stachy/black mold inside 0 outside. 11,000 asper/pen inside 480 outside. all in M3 measurements . in reading its all snapshot in time it is scary for me with health. Recently coughed up sputum that was black/brown trouble breathing like asthma. pustule bites on skin on legs, odd grey hairs that are not grey at roots including beard. doc had giving me antibiotics for chest but still coughing up and wheezing. No money to move, landlord had AC fixed, they put put up plastic on door but it was half open whole time. He was not trained in mold didn't care about my test results. Now having mold remediation company she hired come in. In a letter to her, her response was she had a qualified tester come in. he was a real estate inspector who did mold testing, said the air levels were low and it was not a concern at this time. help
The mold in a refrigerator drip pan won't explain an illness unless you put it in your eye. But building leaks into ceiling or wall cavities could indeed have caused the growth of a significant mold reservoir that is not immediately obvious.
In my opinion and based on field and lab experience over 30 years, air tests for mold, taken alone without a thoughtful inspection are not worth a penny (except for the profit to the testing company).
Question: company won't give copy of air quality test results
(Mar 22, 2012) Tracy said:
I am currently working in a setting which is situated in the basement of a building. We have repeatedly complained of increasing health issues among 8 employees out of 12 working there. The company had air quality testing done but refuse to allow us a copy of the report. We have gained the information that the penicillium/aspergilius count outdoor was zero, in our hallway it was 1600 and in our office it was 5800 per m3.
All of our symptoms are respiratory related from recently diagnosises asthma, pneumonia, repeated sinus infections for one employee 8 since august, chronic coughs and headaches. We did have one employee die prior to the report from pneumonia. Could you please tell me if we need to pursue further action outside of our company since they refuse to cooperate. Can these illness be related to the numbers I have given to you/
One can but wonder what management are thinking if they have testing performed but won't tell you the results. It's suggestive of a problem.
Question: wheezing, sick pets
(Mar 23, 2012) Trish said:
I Had an Inspector into my home Today Of Which I And My Pets Have Lived In For a Year and a Half Now and Since, I Have been Ill With Bonchitus about 50 times now...My Dogs have that hacking cough..wheezing..Cant catch their breath...My Daughter dogs Legs Collapsing now...and I have had What They Are Calling a Stroke, and/or my Left side collapse...I was never told the home had Water Damage,Water pouring in the walls and windows while two years vacant, Flooding at another time,and two people Passing in HERE...without Disclosing that as well.
I and My Dogs continue to get Sick...And the Levels were over9.8, 11.9..Etc...and that was without even checking the Possible water in the walls or ceiling. The inspector quoted , I have NO DOUBT there is MOLD in here...I can Smell The Distinctive Smell.
How Dangerous Is This Until I can Find another Place..and How Much Damage Will this have Caused us To This Point(Living in here for a Year and a Half???..and What IS MY RECOURSE?
You need to consult your doctor and veternarian promptly, and before making any plans regarding the building where you live.
Smelling mold is a reliable indicator - most people recognize mold smells - but doesn't tell us where or how large the problem is. A more competent inspection is probably needed.
Question: sick at the workplace: skin rashes, respiratory illnesses baterial?
(May 11, 2012) D.W said:
The question of what other tests are appropriate would best be decided with advice from an onsite expert who interviews the sick employees about symptoms and who inspects the building thoroughly for clues such as leak history or other issues.
Question: what does our mold test mean
(June 1, 2012) Lori said:
This is what our test showed, what does it mean. Two small areas on floor joist in crawlspace. 161208769-0001 SMI120528M Front Support Beam Aspergillus High*
With respect, Lori, if you hire someone to perform an important test that can involve both health risks and money risks, and if the test person won't tell you what the results mean, you should ask for your money back and hire someone more helpful. I cannot very well interpret the numbers you give while knowing nothing about the building. The lab can't either.
Question: should a cancer patient avoid mold?
(Aug 25, 2012) jerry dupuis,[ dupster1@mnsi.Net said:
I have been told a person with , 'cancer ' should never be exposed to mold spores,
In my OPINION cancer patients and anyone else who has a compromised immune system is very likely at greater risk of illness if exposed to allergenic, toxic or pathogenic substances, including mold at other than incidental, typical outdoor levels.
Question: I have black mold
(Oct 13, 2012) ruth auerbach said:
I have black mold and also eferfescence we were tested at 800 in an airborne check
Ruth knowing so little about your home and the test I can't say if you should stay in the home or not. Insist that your test consultant help you interpret the test. If no inspection was performed the test is unreliable.
Question: how accurate are mold test labs
(Oct 24, 2012) Khalid said:
I know that mold has high variability but What is the precision and standard deviation for the lab?
Good question. Most forensic labs including mold test labs not only pass certification testing but also participate in a "round robin" examination of a lab sample so that the labs can compare results and lab techniques, improving everyone's accuracy.
Forgive me for begging the question but as you put it it's not useful. Given that how the mold sample is collected can result in several orders of magnitude difference in the number of particles collected, meaning that the ability of the sample to accurately represent the test environment can be off by a factor of 10,000 times, the accuracy of a lab count is not a worry.
Please see these two key articles that will answer your question more meaningfully
RE: Khalid's excellent question:
I know that mold has high variability but What is the precision and standard deviation for the lab?
Khalid, the variability in lab precision in mold counts indeed varies by technician, microscope adjustment and calibration, slide preparation, mountant used, magnification at which a sample is examined, and other measures such as the percentage of the trace or sample that is actually examined and counted in the lab
However the choice of test method, particularly where air tests for mold or culture tests for mold produces variation of at least several orders of magnitude in the results. Waving a notebook in the air during a collection of airborne particles, for example, can increase the count by a factor of 100 to even 1000. And using a culture to test for mold in buildings fails to account for the fact that 90% of molds don't grow in culture, or among those that do, a genera/species that likes the culture more than one of its neighbors may quickly reproduce, overgrow its neighbor, and falsely appear as the dominant mold when it was in fact an incidental bystander.
These arguments conclude that mold count variability caused by methodological method choices will generally overshadow variation in lab precision. Test lab managers know this. I have argued against providing "precise" particle counts. But their understandable reply is that test labs respond to market pressures. "If we dont' give counts our legal customers will just go to another lab that does" is a common retort.
All of this means that the importance of an expert visual inspection, noting building history, components, risk areas, visual hazards, and noting occupant complaint history and similar factors are very important in assessing building mold contamination risks, and that without these steps, mere quantitative "mold count" tests are not so reliable.
Question: respiratory problems vs allergic response
(Oct 29, 2012) Scott said:
Hi can you advise if exposure to mould spores, mycotoxins and fragments can cause respiratory problems without the person showing an allergic reaction to the mould?
In my opinion, certainly yes, if you mean other types of allergic response such as itching; but you should discuss this with your doctor, not online.
(Jan 24, 2013) Saeed Sheikh Muhammad said:
Now-a-days I am interested to find out the referece values of yeast & mould in Nut candies & Nut paste for food analysis.
Question: CB points out problems with mold related illness, misdiagnosis, and very sensitive transmission of mycotoxins
(Feb 5, 2013) CB said:
Wowza-- keep it up! This is one of only two websites I've read in 9 months that is completely free of misinformation, disinformation, errant conclusions or pure arrogant ignorance. I'm a physician, early 40's, brought to my knees over 6-8 years by the insidious progression of complex multi-system mycotoxicosis. After being misdiagnosed by over a dozen docs (including the infamous Mayo), it was desperation, near death, the internet and one laboratory that helped save my life. However, the diagnosis was just the beginning.
While there is effective treatment, it is expensive and difficult to access. To avoid a huge tangent, I'll just say that there are IV therapies that are extremely effective at clearing circulating and tissue-bound mycotoxins, as well as those that decrease excessive mycotoxin-induced neural inflammation and restoration of depleted GABA stores (but big Pharma doesn't want us to know about these--since the ingredients are commonly described as "not approved for, intended to diagnose, nor treat any illness").
Back on point...... Time, lots of struggling and trial and error, and exorbitant expense have ultimately led us to our epiphany: while molds and their antigenic structural components largely correlate with the "asthma/allergy spectrum," their mycotoxins are a separate, MASSIVE, grossly-under-recognized human health issue. Residual mycotoxins are being retained on fibers of clothes, linens, carpet, insulation, furniture......
And "transfer" from these does occur. In the absence of a DESPERATATELY-needed mycotxin-specific organic compound detector, we've had to indirectly learn some lessons.
With over 100 symptom- and timing-based urine mycotoxin levels in several people, we've documented non-contact airborne transfer from clothing (worn by a person from an effected building) to multiple people who simply spent an hour in the same room with them. We've documented skin-skin transfer and animal hair-human transfer. Multiple individuals had elevated Tricothecene levels after 40 minutes
(Feb 5, 2013) CB said:
in a private hot tub (the hot tub water was subsequently tested, and low-and-behold had Tricothecene levels above 40 ppb-- i.e. more than 200 times the toxic threshold). This exposure resulted in one party having a Tricothecene level that peaked 4 days later at 46 times above the toxic threshold, and severe neurocognitive, GI, and rheumatologist symptoms that precluded a full work schedule for weeks).
I've had numerous tests at my house and office, and thorough necessary remediation efforts at both. Two issues have arisen over the past 4-5 months. First, recurring symptoms and correlative elevated mycotoxin urine levels led to identification of suboptimally-remediated sources of mold in attic insulation (despite supposed negative post-remediation evaluation). Second, and subsequently, recurring symptoms/elevated toxin levels led to realization that certain areas of carpet were (very likely) retaining mycotoxins in the absence of persistent/recurrent mold (the carpet in question never, itself, had a primary mold issue; and repeat air sample tests of the "intentionally-disturbed" carpet were not remarkable...... yet consistent temporally-based illness issues suddenly resolved upon replacing the carpet). Man, we really need some tech geeks and a couple of engineers and PhD's to develop a real-time VOC meter for mycotoxins.
Anyway, I apologize for the verbal diarrhea. But wanted to say thank you for your efforts, open-mindedness, quest for truth and accuracy, and passion. While the upper and lower airways suffer well-established collateral damage from antigenic mold particles, mycotoxins are silently causing profound issues including, but not limited to: Autoimmune, neurodegenerative, psychiatric, rheumatologic, endocrine, immunodeficiencies, cardiovascular, dermatological, etc.
One huge confounding variable is that everyone claims to be a mold expert, and 90% don't have a clue that they don't have a clue. My other massive concern is the current dangerous arrogant ignorance of the US medical field regard
Thank you for these helpful remarks. I've moved your comments into the article for preservation.
I agree with your concern that "mold experts" vary widely in expertise as well as in avoidance of conflict of interest. My dog was a certified mold inspector by the way - it was easy to send in some money and get a diploma for her. A weekend nor a week do not an expert make, of a dog nor of a human being. You can quote my OPINION on that.
Question: buyers inspection said there's mold: is this a concern?
6/25/2014 Jack said:
I am in the process of selling my house. The potential buyers had a building inspection done. The inspector found what looks like dust on the floor joists in the basement. This is not a surprise since I have used the basement as a work room for wood working. A mold inspection was done and the only thing reported was Aspergillus/Penicillium *High*. At the bottom of the report the company defines "Category: Count/per area analyzed
Rare: 1 to 10 Low: 11 to 100 Medium: 101 to 1000 High: >1000"
Is this proof of a situation which we should be concerned about or not?
Thanks for your help,
I don't know what that "high" means - spores per inch, spores per cubic meter of air, spores in a culture, spores on a swab, spores in the mind of the inspector or what. Also waving a notebook changes the number by several orders of magnitude if air testing was performed, so such tests are wildly inaccurate, especially if they do not detect a problem.
However high levels of indoor Aspergillus/Penicillium is worth looking into. It may have nothing to do with wood dust from a shop. A more intelligent assessment would look at the building leak history, figure out the locations of highest-risk of mold contamination, and examine those areas directly.
Follow the water: look carefully at the home's leak history and what materials have been wet. Inspect those areas, invasively if necesary. If examining the highest-risk points in the home do NOT find an actionable mold contaminated area to clean-up, you've done about as much as is reasonable. That doesn't guarantee that there is no mold problem to find and remove, but the approach can argue that there is no current information that appears to justify further invasive inspection, demolition, etc.
Don't panic - which leads to wasting money, but proceed with some caution.
Questions & answers or comments about standards for acceptable or unacceptable toxic mold spore counts, levels, or measurements in building interiors.
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
Search the InspectApedia website
HTML Comment Box is loading comments...
Technical Reviewers & References