Mold exposure standards - various U.S. and other Countries standards for allowable mold exposure
Effects of mycotoxins, toxicity of Stachybotrys, Penicillium, Aspergillus
How toxic is black mold? which black molds are harmless?
Questions & answers about standards for acceptable or unacceptable toxic mold spore counts, levels, or measurements in building interiors
This InspectAPedia technical article explains airborne mold spore counts, surface density, and other measures of the exposure level of allergenic, infectious, and levels of toxic
mold in residential 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?
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What mold spore levels indicate contamination in buildings ?
Mold spore counts and mold culture results are not reliable alone for evaluating a mold problem
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.
Reasons Simple Airborne Mold Counts Alone Are Not Good Indicators of Risk
"Mold Levels" warning: single number "mold levels" are unreliable as a measure of health risk in buildings for several reasons including at least the following:
Particle levels vary: 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. Simple mechanical disturbance like turning on or off a fan can completely change individual measurement results. Short term measurements are therefore inaccurate.
Human sensitivity varies: 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.
Particle toxicity varies: There is very wide variance among the toxicity of individual mold species, ranging from none to probably highly toxic, pathogenic, or even carcinogenic.
Spore size or mass 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 vary, even within an individual species, depending on what
substrate the species is growing on in a particular instance, e.g. wood vs. drywall.
Viable vs. non-viable "spore counts" 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, while completely failing to disclose a problem mold which is present but which simply does not grow in the culture media used, or is
overgrown by another species in that media. For more details see Mold Spore Counts:
are indoor fungal spore counts valid? for further explanation.
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
Contamination levels of non-specific allergenic, pathogenic, or toxic fungal spores
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.
Acceptable levels for individual species vary since species toxicity varies widely as does spore size, weight, and other features which affect risk
to building occupants. E.g. Aspergillus/Penicillium in a "clean" residential building study was at a mean of 230, in buildings known to have a
moisture or flooding problem it was at 2235 and in mold contaminated buildings the figure was 36,037.
AAAAI provides an important qualification about mold and pollen counts as reported by that agency which we quote just below:
"These mold levels were determined based on outdoor exposure to natural occurring spores in the environment and should not be applied to indoor exposure which may represent an entirely different spectrum of spore types.
These definitions would allow comparison between sites across the country. They are based on ecological measurements, not health effects. However, assuming dose/response relationships are the same across the country, the definitions are probably more appropriate than a definition based on local numbers. This does mean that, for some stations, some categories will never be high."
- AAAAI.
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:
Concentration Qualitative Assessment of Mold Contamination Levels
Colony Forming Units/gram - cultured mold samples as indicators of mold level in buildings
less than 10,000 CFUs of mold per gram in a culture sample plate = low mold contamination level
10,000 to 100,000 CFUs of mold per gram in a culture sample plate = medium mold contamination level
100,000 to 1,000,000 CFUs of mold per gram in a culture sample plate = medium to heavy mold contamination level
> 1,000,000 CFUs of mold per gram in a culture sample plate = heavy
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:
the airborne level of particles varies enormously moment to moment - opening a door or closing a window, waving a notebook at a table, or walking across a carpet completely change the particle level
at most of our detailed investigations we find that unless all of the building windows are open and wind is blowing through the building, the air exchange rate between indoor and outdoor air confounds a comparison with outdoor air
outdoor air particle levels and mold levels vary enormously as a function of weather conditions; with snow cover there is little airborne mold outdoors; after a rain or at certain other weather conditions there can be an explosion in the level of outdoor spores, confounding the indoor measurement
nearly all indoor/outdoor airborne mold level comparisons fail to focus on differences in genera and species between indoors and outside; even relatively low indoor airborne or dust-borne mold levels might indicate a problem in the building, depending on just what is identified in the sample
indoor and outdoor basidiomycetes are often mistaken for and compared with Penicillium/Aspergillus levels - a serious error
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.
We suspect that focusing only on "colony-forming-units" (that is, viable mold that will grow) is not a very reliable way to check out a building. That's because
90% of mold species will not grow on culture media
Even if a particular mold species will grow on culture media, it may be overgrown and thus under-represented by a another mold that was present in the same sample at a much lower rate but which happens to like the culture media better than the more frequent spore or even a more toxic mold spore
Spores settle out of air at very different rates depending on spore size and mass. Just as some very small snakes are more venomous and potentially dangerous than some very big snakes, size, and thus settlement rate out of air, and thus occurrence on a mold culture settlement plate, does not accurately represent what building occupants are breathing.
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.
Mold Exposure Levels - Sources of Variation in Mold Toxicity - a warning about single numbers
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.
Mold Spore - Particle toxicity varies for many reasons
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.
Viable vs. non-viable toxic mold "spore counts"
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.
Other U.S. & World Government Mold Exposure Standards
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
The Ontario Ministry of Labour
incorporates the New York City Mold guidelines in
a Hazard Alert on Mould in Workplace
Buildings issued in 2000.
California Energy Commission
See
California Mold Disclosure Law, and the California Department of Health Service / Environmental Health Investigations Branch report on whether it is feasible to adopt permissible exposure limits (PELs) for indoor mold
Former building biology reference values for molds, SBM-1998 through SBM-2003 (using YM Baubiologie Agar at a culture temperature of 20-24 °C, colony forming units CFU): in the air < 200 no, 200-500 slight, 500-1000 strong, > 1000/m³ extreme anomaly (values refer for indoor air when outdoor reference levels are relatively low, below 500/m³); on surfaces: < 20 no, 20-50 slight, 50-100 strong, > 100/dm² extreme anomaly (values refer to surfaces that are subject to common and regular cleaning practices)
WHO: pathogenic and toxigenic fungi are not acceptable in indoor air; from 50/m³ of a single fungal species, the source(s) needs to be identi-fied; a mixture of common fungi typical for a given location (e.g. cladosporium) can be tolerated up to 500/m³. Senkpiel/Ohgke: Indoor concen-trations that are over 100/m³ above the outdoor air indicate a problem. EU statistics for apartments: < 50/m³ very low, < 200/m³ low, < 1000/m³ medium, < 10000/m³ high, > 10000/m³ very high. See 'Schimmelpilz-Leitfaden' by Environment Agency (Germany) for assessment details.
Massachussetts mold legislation: Massachusetts, Michigan, New Jersey, New Mexico and New York, either have or are considering similar or modified mold protection acts similar to California's Toxic Mold Protection Act.
Montana and other U.S. States mold disclosure legislation: requires building seller disclosure of mold during real estate transactions: Louisiana, Michigan, Montana, Nevada, New York, Oregon, Texas, & Washington either have mold disclosure laws or mold disclosure bills in committe. A California disclosure bill failed to pass in 2002.
New York City Department of Health Mold Severity Levels:
New York City Guidelines on Assessment and Remediation of Fungi in Indoor Environments - updated in 2008. The New York City Guidelines on Assessment and Remediation
of Fungi in Indoor Environments, 2000, issued by the
New York City Department of Health,
have are been widely accepted and quoted by public
health departments in various U.S. states, Canadian povinces, and other regulatory
agencies in other countries. - New York City Department of Health, Bureau of Environmental & Occupational Disease Epidemiology "Guidelines On Assessment & Remediation Of Fungi In Indoor Environments".
The Ontario Ministry of Labour
incorporates these guidelines in
a Hazard Alert on Mould in Workplace
Buildings issued in 2000.
USA Associations - General:
American Conference of Governmental Industrial Hygienists (ACGIH) "Bioaerosols: Assessment and Control" Book, 1999
Institute of Inspection, Cleaning & Restoration Certification (IICRC) Document S500
WHO - World Health Organization mold exposure standards- see World Health Organization Mold Bulletin. World Health Organization mold exposure guidelines specify that pathogenic and toxigenic fungi are not acceptable in indoor air as follows:
Mold spore counts of over 50/m³: for a single mold species, identify the source of mold
Mold spore count sup to 500/m³: a mixture of common fungi typical for a given location is acceptable - an example would be the most common mold genera found outdoors, Cladosporium sp.
According to Senkpiel/Ohgke: Indoor concentrations that are over 100/m³ above the outdoor air indicate a problem (we would argue that this standard is inappropriately tight) -- 'Schimmelpilz-Leitfaden', German Environmental Protection Agency
World Health Organization (WHO) "Health Guidelines on Biological Agents in the Indoor Environment" (DRAFT as of August 4, 2000)
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.
The Toxic Effects of Mycotoxins on Humans, Sheep, & Possibly on Pets
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:
The right environment must be
present for mycotoxin-producing molds to actually produce mycotoxins. [I
have pointed out elsewhere that a given mold may produce or not product
mycotoxins as a function of varying environmental conditions including the
presence or absence of particular nutrients available to the mold -- i.e.
it may depend on just what material is supporting the mold growth, not
simply on the presence of mold and moisture.]
The mycotoxin(s) must have a
pathway from the source to a susceptible person.
The pathway may be direct contact with moldy material, inhalation of
airborne spores or fungal fragments or of contaminated building materials.
Important in understanding this pathway and the significance of
"moldy odors" which We ascribe to volatile organic compounds
given off by some molds under some conditions, mycotoxins are not
volatile.
Therefore, as Arora explains, airborne mycotoxin transmission
has to be by inhalation of aerosolized mold or mold-contaminated
materials. We point out elsewhere that the particle levels in air in a
building vary widely over time for many reasons. However it should be no
surprise to find airborne mold or mold-contaminated debris in a moldy
building, particularly if demolition or improper "mold
remediation" is going on.
The person has to absorb a
toxic dose of the mycotoxin(s) over a sufficiently short time period. "Very little is known about what constitutes a toxic dose for humans
-- see Stachybotrys chartarum mycotoxin discussion below.
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.
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.
Contamination levels of specific allergenic or toxic mold spores
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.
http://www.stockton-press.co.uk
See references below for important additional information such as mold testing, cleanup and mold remediation guideline resources.
Stachybotrys chartarum in air
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.
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.
Penicillium sp.
"Clean" residential buildings are typically 230/m3 +/- 630. Buildings with evidence of flooding are typically much higher: 2200/m3 and
mold-damaged buildings are typically extremely high in comparison: 36,000/m3.
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.
Aspergillus sp.
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.
Frequently Asked Questions about standards for acceptable or unacceptable toxic mold spore counts, levels, or measurements in building interiors.
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
Reply:
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.
If you have evidence that conditions in your building have made you ill, particularly if your doctor agrees, you might want to give a head's up warning to building management, in writing, since others may be affected too.
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
Reply:
My School:
I agree and am glad you read the article. There is a lot of confusion between precision and accuracy. What makes sense is to combine testing with an expert inspection of the premises for visible mold and for conditions that create a risk of hidden mold reservoirs at a risk high enough to merit further investigation.
Next, an expert look at the test samples and test results might be useful in making everyone more confident (or less) in the inspection and test results for work done to date. A count of 5000 spores/meter could be quite significant depending on - what is in the count, what type of particles, presence or absence of spore chains and cetain other particles, and comparison with tests taken in control areas.
Finally, because of the variability I've described, it's a negative result that is most suspect - that is, the indication that there is not a problem.
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!!!
Reply:
MOLD EXPERT, WHEN TO 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.
Thank you for any insight!! - My work has mold
Reply:
My Work:
The numbers you quote suggest an indoor mold contamination problem. Did you ask the mold expert who performed the test to interpret the data, inspect the building, give advice? If not, you folks didn't get much of value.
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
Reply:
Anon:
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.
Dust containing just about anything can be a respiratory irritant and for people at extra risk such as asthmatics, can be more of a problem.
At MOLD EXPERT, WHEN TO HIRE we outline some considerations that can help you decide if further investigation, testing, or analysis of your work area are appropriate.
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
Tracey:
Mold spore viability varies by species and condition; some spores can become very dessicated (dried) and remain in place for months or even years, later returning to active growth if conditions of moisture, temperature, and other factors are favorable.
Further, some mold spores may remain toxic, for example containing mycotoxins, even if the spores are "dead" - in the sense that they would not return to active growth.
These are reasons that we emphasize that removing mold contamination is important and that "solutions" to mold contamination that focus on "killing mold" are a mistake.
The fact that you report a previous death in a home and illnesses in a home where the death was associated with mold contamination and that you later worked in such a home performing cleaning, does not alone provide enough data to assert that you caused serious cross-contamination in a second structure by having worked in the first one.
But I can imagine some potential problem sources including use of a non-HEPA rated vacuum cleaner to clean the moldy home - followed by use of the same equipment in another building; the second use risks blowing potentially harmful or irritating dust into the second building.
Conversely, just having dusty moldy clothing would not, for most people, be sufficient to cause a serious cross-contamination in another building. Washing or dry cleaning the clothing will generally be sufficient to remove that concern.
There could be an exception if the clothes were not cleaned. I had a case in which a woman became ill from exposure to high levels of Aspergillus in a leaky mold-contaminated modular home. She was hospitalized, had become hypersensitive to airborne mold, and had apparently recovered. When she was scheduled to return home her husband brought her clothing that had been stored in a closet in (the moldy) home. When the clothes were brought into her hospital room she immediately developed a serious reaction. My investigation found hidden mold reservoirs in the source home.
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 EXPERT, WHEN TO 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 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.
Is the mold/musty smell caused by spores or are spores only released if they are disturbed - Brian
Reply:
Brian, you should contact your base medical and health officers for advice on inspecting your home for health worries, and see MOLD EXPERT, WHEN TO 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.
Questions & Answers regarding this article
Questions & answers about standards for acceptable or unacceptable toxic mold spore counts, levels, or measurements in building interiors.
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Additional technical contributors & reference sources for this article are listed below.
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AAAAI - Asthma and Immunology's Aeroallergen Network is a national U.S. network of data gatherers that is responsible for reporting current pollen and mold spore levels to the public. American Academy of Allergy,
Asthma and Immunology,
555 East Wells Street, Suite 110,
Milwaukee, WI 53202. AAAAI can be contacted also by their website at www.aaaai.org
AAAAI provides a table of interpretations of mold and pollen counts (of airborne particles/M3 of air) at http://www.aaaai.org/nab/index.cfm?p=reading_charts
Bioaerosols: Assessment and Control. Janet Macher, ScD., M.P.H. American Conference of Governmental Industrial Hygienists, Cincinnati, OH. 1999
Building Biology Evaluation Guidelines, available in English Language Translation, provided by the German government, original citation: www.baubiologie.de/downloads/english/richtwerte_2008_englisch.pdf
BAUBIOLOGIE MAES Schorlemerstr. 87 41464 Neuss Telefon 02131/43741 Fax 44127 www.maes.de
Canada: Canadian National Toxic Mold Centre, and also see Moldy Houses: Why They Are and Why We Care & Additional Analysis of Wallaceburg Data: the Wallaceburg Health and Housing Studies) Fungal Contamination in Buildings: Health Effects & Investigation Methods, Health Canada, Minister of Health, original citation: www.hc-sc.gc.ca/ewh-semt/alt_formats/hecs-sesc/pdf/pubs/air/fungal-fongique/fungal-fongique-eng.pdf
California: California Department of Health Service / Environmental Health Investigations Branch report on whether it is feasible to adopt permissible exposure limits (PELs) for indoor mold - see SB 732 (Toxic Mold Protection Act of 2001, Implementation Update (August 2006)
Canada: Mould Guidelines for the Canadian Construction Industry - original source www.cca-acc.com/documents/electronic/cca82/cca82.pdf
IICRC S520: Standard and Reference Guide for Professional Mold Remediation 2nd Edition. Institution of Inspection, Cleaning and Restoration Certification. Vancouver, WA. 2008
IICRC S500: Standard and Reference Guide for Professional Water Damage Restoration 3rd Edition. Institution of Inspection, Cleaning and Restoration Certification. Vancouver, WA. 2006
J.R. Tucker, EMS-sales, 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. [This is a serious limitation of the standards since the spores of different genera and species
vary widely in total size, mass, and toxicity. -DF]
Larry Syzdek, Albany, NY. personal communication at PAAA aerobiology conferences.
Listeriosis, Discussion of, Penn State University,, Oct 27, 2002. "Listeriosis is a bacterial infection usually of the brain.
Listeriosis is common in ruminants, pigs, dogs, and cats, some wild
animals, and humans. Animals infected with Listeria can show
clinical signs of abortions or nervous system disorders." Cooperative Extension
The Pennsylvania State University, University Park,
Pennsylvania 16802
FAX (814) 863-6140. See this US CDC article on Listeriosis for more information.
National Allergy Bureau, is hosted by the AAAAI and can be contacted at www.aaaai.org/nab. "The National Allergy Bureau™ (NAB™) is the section of the American Academy of Allergy, Asthma and Immunology's (AAAAI) Aeroallergen Network that is responsible for reporting current pollen and mold spore levels to the public."
OSHA: Brief Guide to Mold in the Workplace, original citation: http://www.osha.gov/dts/shib/shib101003.html
Post-Remediation Verification and Clearance Testing for Mold and Bacteria – Risk Based Levels of Cleanliness Assurance 1st Edition. Robert C. Brandys, PhD, MPH, PE, CIH, CSP, CMR and Gail M. Brandys, MS, CSP, CMR, CIEC. OEHCS Publications. Hinsdale, IL. 2003
Recognition, Evaluation and Control of Indoor Mold, American Industrial Hygiene Association. Fairfax, Va. 2008 Fungal Contamination: A Manual for Investigation, Remediation and Control. Hollace S. Bailey, PE, CIAQP, CIE, CMR. Building Environment Consultants, Inc. Jupiter, FL. 2005
U.S. CDC - Mold Questions and Answers: Questions and Answers on Stachybotrys chartarum and other molds - original source: www.cdc.gov/mold/pdfs/stachy.pdf, Questions and Answers on Stachybotrys Chartarum and Other Molds. Centers for Disease Control and Prevention, National Center for Environmental Health. March 9, 2000.
US EPA: Mold Remediation in Schools and Commercial Buildings: original EPA source - www.epa.gov/mold/pdfs/moldremediation.pdf
USP 797 Guidebook to Pharmaceutical Compounding - Sterile Preparations, U.S. Pharmacopeai, Web search 01/23/2012 and available online at usp.org/products/797Guidebook/
USP 797 Standards and Guidelines with USP 797 Testing Lab Services, EMLab P&K, web search 12/1/2011, original source emlab.com/s/services/USP_797.html - EMLab discusses USP 797 as it pertains to mold testing, bacteria testing, and other environmental and health related tests. For mold testing using surface cultures (swabs) that and other testing laboratories typically use broad-spectrum mold culture media such as Malt Extract Agar (MEA) or Cormeal Agar (CMA) - these media do well culturing Penicillium. Aspergillus, and Cladosporium, but beware: in our OPINION other important molds may be present, even dominant in the building but may not show up in culture tests.
Mold Exposure Standards - levels of allergenic & toxic mold: how much mold means a problem? - http://www.inspectapedia.com/sickhouse/Mold_Standards.htm
Guidance for Clinicians on the Recognition and Management of Health Effects Related to Mold Exposure and Moisture Indoors, [on file as /mold/Mold_Guide_UConn.pdf] - Eileen Storey, MD MPH, Kenneth H. Dangman, MD PhD MPH, Paula Schenck MPH, Robert L DeBernardo MD MPH, Chin S Yang PhD, Anne Bracker CIH MPH, Michael J Hodgson MD MPH, University of Connecticut Health Center, Division of Occupational and Environmental Medicine, Center for Indoor Environments and Health, 266 Farmington Ave., Farmington CT 06030-6210, 30 September 2004. [We have edited this file to remove blank pages in order to speed its load-time and to add a link back to this website.] This document was designed to help the healthcare provider address patients with illnesses related to mold in the indoor environment by providing background understanding of how mold may be affecting patients. The guidance was published in 2004, with support from a grant by the U.S. EPA, by the Center for Indoor Environments and Health, or CIEH at the University of Connecticut Health Center. " -- original source: oehc.uchc.edu/images/PDFs/MOLD%20GUIDE.pdf (1.13MB PDF file, slow loading)
History of major mold outbreaks: see the WHO bulletin above, also see a nice summary of the history of major mold related illness outbreaks is at moldbacteria.com/newsletters/2005/sep2005.html provided by Dr. Jackson Kung'U, a microbiologist, mycologist, writing for that website.
...
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
Kansas State University, department of plant pathology, extension plant pathology web page on wheat rust fungus: see http://www.oznet.ksu.edu/path-ext/factSheets/Wheat/Wheat%20Leaf%20Rust.asp
"A Brief Guide to Mold, Moisture, and Your Home",
U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
Associations: Sick House, Sick Building, SBS - Air Quality, Government, Private Associations and Information Resources
Atlas of Clinical Fungi, 2nd Ed., GS deHoog, J Guarro, J Gene, & MJ Figueras, Centraalbureau voor Schimmelcultures, Universitat Rovira I Virgili, 2000, ISBN 90-70351-43-9 (you can buy this book at Amazon)
Atlas of Indoor Mold, Online Clinical Mold Atlas, Toxins, Pathogens, Allergens and Other Indoor Particles - Medical Health Effects of Mold (separate online document)
Black Mold that is Harmless Photos of recognizable, usually harmless black mold on wood, bluestain, ceratocystis, ophistoma
Building Floods: quick steps after a building flood or plumbing leak can prevent costly mold contamination
Classes of Mold: what types of cosmetic, allergenic, or toxic mold are a problem? Can mold be cleaned-up successfully?
"A Brief Guide to Mold, Moisture, and Your Home", U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
"Disease Prevention Program for Certain Vegetable Crops," David B. Langston, Jr., Extension Plant Pathologist - Vegetables, University of Georgia (PDF document) original source: www.reeis.usda.gov/web/crisprojectpages/209797.html
"Disease Prevention in Home Vegetable Gardens,"
Patricia Donald,
Department of Plant Microbiology and Pathology,
Lewis Jett
Department of Horticulture, University of Missouri Extension - extension.missouri.edu/publications/DisplayPub.aspx?P=G6202
Fifth Kingdom, Bryce Kendrick, ISBN13: 9781585100224, is available from the InspectAPedia online bookstore - we recommend the CD-ROM version of this book. This 3rd/edition is a compact but comprehensive encyclopedia of all things mycological. Every aspect of the fungi, from aflatoxin to zppspores, with an accessible blend of verve and wit. The 24 chapters are filled with up-to-date information of classification, yeast, lichens, spore dispersal, allergies, ecology, genetics, plant pathology, predatory fungi, biological control, mutualistic symbioses with animals and plants, fungi as food, food spoilage and mycotoxins.
OTHER IAQ ISSUES: How To Find and Address Other Indoor Air or Indoor Environment Contaminants Besides Mold
Mold or allergens may not be the only or even the main indoor environmental contaminant. Don't let media attention to mold
cause so much enviro-scare fear that other, possibly more urgent hazards go un-addressed.
Ozone Warnings - Use of Ozone as a "mold"
remedy is ineffective and may be dangerous.
Pet control - if you can't say goodbye to your bird, cat, dog, guinea pig, hamster, tropical fish, then limit the
areas they occupy and limit the airflow from that area to sleeping or other areas of the building, use allergenic
bedding, eliminate wall-to-wall carpeting, improve housecleaning including use of a HEPA-rated vacuum cleaner. For more details
see our article Dog, Cat, and Other Animal Dander - Information for Asthmatics and Indoor Air Quality
Rodents, Mice, Squirrel Control - I find high levels of mouse and rodent dander, fecal dust, and urine-contaminated dust in some buildings,
and high levels of these materials in building insulation in those locations. If you have a mouse problem, particularly if mice and their waste (fecals or urine) are contaminating
the building HVAC or building insulation, may need both steps to clean up or remove infected materials and steps to stop an ongoing
rodent problem. If squirrels are a problem, the cleanup needs to include closing off entry openings into the building. Get some
help from a licensed pest control expert.
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to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems