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Photograph of toxic gas testing devices. Mold MVOCs, Moldy or Musty Odors, Toxic Mold & Toxic Gas Testing Guide

MVOCs and mold:

This article explains MVOCs or mold volatile organic compounds, what makes MVOCs, the meaning of the presence or absence of moldy smells in buildings, and MVOC testing.

This article series lists and compares classes of mold, air, gas, test methods used in indoor air quality investigation methodology in searching for possible causes of respiratory illness, asthma, immune system disorders, rashes, skin disease, psychological and neurological disorders, eye infections, or other symptoms which may have a physiological and environmental component.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Sampling for Mold Volatile Organic Compounds - MVOCs and other Mold-Related Gases in Buildings

Airborne debris indoors (C) Daniel FriedmanMVOCs in the indoor environment can affect the health of humans and other animals and may be detected with good reliability by blood testing. (El Aroussi 2022, Elmassry 2020 et als)

And as researchers have pointed-out, although there are other sophisticated methods for identifying microbes or detecting their presence, analysis of volatiles such as MVOCs is always fasater, less-invasive, and probably less costly. (Lemfack 2013).

However, as we explain below in our comments about mold sniffing dogs, not all molds generate MVOCs, and even molds that do generate MVOC's don't do so at consistent levels, all the time, and MVOC production even MVOC production may also vary significantly depending on the nutrients in the surface upon which the mold is growing, indoor humidity levels, and even the levels of light. (Kalalian 2020)

Adding uncertainty, some researchers point out that

Of more than 200 compounds identified as MVOCs in laboratory experiments, none can be regarded as exclusively of microbial origin or as specific for certain microbial species. Thus, the recognition of microbially contaminated areas by MVOC measurements is not successful with current methods. (Korpi 2020) [Not everyone agrees with this conclusion. (Ruzzanyi 2003)]

If the humidity, temperature, light, and other factors don't cause a particular MVOC-generating mold to release this gas, you're not going to detect it on the day of the inspection and test. Just later.

Our illustration shows simple gas detection tubes that can be used as a rough detection mechanism for certain gases in air. Highly-accurate MVOC detection and the identification of MVOC constituents requires far more-sophisticated equipment such as gas chromatography equpment using any of several (flame ionization, mass spectrometry, etc.) that are beyond the capacity of typical environmental inspections and inspectors. (Visual inspection for mold and a thorough building inspection and review of its leak history may perhaps be found more basic, reliable, and practical when assessing the risk of buldiing mold contamination.)

At MOLD ODORS, MUSTY SMELLS we discuss the variations in the indoor environment that can turn on or turn off mold smells in a building.

Production of toxins and microbial volatile organic compounds (MVOCs) by fungi in an environmental sample is dependent upon many factors, such as the substrate on which mold is growing, relative humidity and temperature in the moldy environment; the relative importance of each of these factors in toxin production is poorly understood.

But it is clear that the level of MVOCs in a building varies widely from none detected to high, even when the genera/species of mold present include MVOC-producing molds. That is, even an MVOC-producing mold species will not always produce detectable odors and gases.

Indoor and outdoor microbial environments are complex, dynamic and transient in nature, and sampling results will change with time. Viability of bacteria and fungi is influenced by environmental conditions such as relative humidity, available nutrients and temperature. Important microbial ecology factors, such as the presence of competing bacteria, fungi, production of anti fungal and antibacterial metabolites, and insects greatly influence viability.

According to a US EPA Mold and Water Damage Study, Some micro-organisms, including molds, also produce characteristic volatile organic compounds (VOCs) or microbial VOCs (mVOCs). Molds also contain substances known as beta glucans; mVOCs and beta glucans might be useful as markers of exposure to molds.

Some molds are capable of producing toxins (sometimes called mycotoxins) under specific environmental conditions, such as competition from other organisms or changes in the moisture or available nutrient supply.

Molds capable of producing toxins are popularly known as toxigenic molds; however, use of this term is discouraged because even molds known to produce toxins can grow without producing them (6). Many fungi are capable of toxin production, and different fungi can produce the same toxin.

MVOC Testing Does Not Generally IDentify the Source of the mold smell or musty odor problem

Even if we detect MVOCs, is that the problem mold in the building? If we don't detect MVOC's does that promise there is no problem mold? No.

Photograph of toxic gas testing devices.

Toxic or irritating gases such as mold-produced VOC's, MVOC's, or other odors, toxic chemicals, and combustion products can be important as life-safety concerns may be involved. Unfortunately no single test or tool can detect all possible building contaminants.

We use methods and equipment which can test for common contaminants.

If the identity of a specific contaminant is known in advance we can also test for a very large number of specific contaminant gases in buildings.

We use gas sampling equipment provided by the two most reliable companies in the world,

Draeger-Safety's [offsite link http://www.draeger-safety.com/ST/internet/US/en/Products/Detection/Drager-Tubes/Pumps/accuro/pd_accuro.jsp ] detector-tubes and Drager accuro™ bellows pump, the

Gastec™ cylinder pump and detector-tube system produced by Gastec or Sensidyne, [offsite link - ] and we also use

Sensidyne's Gilian air pump. [offsite link - http://www.sensidyne.com/GIL/gilMain.htm

For broad screening for combustibles and a number of other toxic gases and for leak tracing we also use Amprobe's Tif8850. All of these instruments, their applications, and sensitivities (minimum detectable limits) for specific gases are described in

Our GAS EXPOSURE SCREENING TEST describes gas testing procedures, instruments, detection limits, and it lists some of the toxic (or other) indoor gases for which we can test, depending on the building complaint and building conditions.

Health Effects of MVOC Exposure

Depending on individual sensitivity and health, indoor air quality complaints about moldy odors or smells or MVOCs range from none to allergic or asthmatic reaction to complaints of disorientation and neurological effects.

Please see MYCOTOXIN EFFECTS of MOLD EXPOSURE.

We distinguish between building related complaints - reports from individuals that an illness appears to be related to spending time in a particular building, and scientific controlled-case studies which have documented certain relationships between exposure to various substances (such as mycotoxins) and illnesses in humans or other animals. Anecdotal evidence associating building related illnesses and mold is often compelling even when the medical research data remain incomplete.

See MOLD RELATED ILLNESS GUIDE

and MOLD RELATED ILLNESS SYMPTOMS.

Mold Sniffing Dogs as a Building Screen for Mold

Client Comment on experience with mold-sniffing dog

I know you don't give much credence to the mold dog but he did point to the outer wall of the closet that was not remediated.

(The inspector put a hole in the wall and tested the spot and it came out nothing.) The dog also pointed to the wall in the dining room but a little further away from where the remediation left off.

(Again, the inspector did a test and found nothing.) It was uncanny that the dog identified the 2 spots that were very close to the remediation.

The dog also pointed to the HVACs which were cleaned thoroughly twice (once by XXX and again by YYY.)

Mold sniffing dogs are unreliable, even though though they're fun.

For details, see INEFFECTIVE MOLD PRODUCTS for an explanation of why mold sniffing dogs make poor mold detectives and why it's not good for them anyway.

There's no doubt that a dog can be trained to smell mold. Dogs have a very sensitive sense of smell and can detect very low levels of what they are trained for.

What is the dog smelling? MVOCs. But there are a few shortcomings of relying on animals as mold investigators:

MVOCs often remain at low levels even in areas where mold remediation has been carried out; if our little buddy sniffs and points to a wall that has been remediated we're unsure if it's a new problem or a few molecules left from a remediated problem. There are no independent, peer reviewed studies demonstrating that we can relate a mold-dog's sniff-and-point to the completeness of a building survey for problematic mold reservoirs.

Not all molds generate MVOCs, and even molds that do generate MVOC's don't do so all the time.

If the humidity, temperature, light, and other factors don't cause a particular MVOC-generating mold to release this gas, you're not going to detect it on the day of the inspection and test. Just later. Even if we detect MVOCs, is that the problem mold in the building?

Beagles & most other dogs are short as dogs go - certainlyh less than 6' 8" tall, and therefore, are not good at sniffing out MVOC's that telltale a mold problem high in a building wall or in a ceiling. Have you ever seen the mold-dog handler swing his/her partner through a loop to make a pass at a ceiling or at the top of a wall?

Beagles are cute, though.

MVOC Smell or Odor Removal

Spraying a biocide at a mold remediation project (C) Daniel Friedman

The steps in curing a moldy smell or MVOC odor complaint or getting rid of MVOCs from various sources in buildings have been moved to a separate article.

Please see MVOCs & MOLDY MUSTY ODOR REMOVAL.

 

Research Eexplains & Defines Mycotoxins & MVOCs

and their interrelationship

Kalalian, Carmen, Letizia Abis, Antoine Depoorter, Bastien Lunardelli, Sébastien Perrier, and Christian George. "Influence of indoor chemistry on the emission of mVOCs from Aspergillus niger molds. - cited & discussed at InspectApedia.com

Illustration of factors in variation of indoor MVOC levels, Katalian (2020) cited just below. [Click to enlarge any image]

 




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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2019-12-19 by (mod) - What's the difference between MVOCs and Mycotoxins ?

Sure Lorie

An MVOC or Microbial Volatile Organic Compound - are volatile gases mixed into building air (if indoors) and that characteristically are recognized by a "moldy" or "musty" smell;

Most people can smell MVOCs (Elmassary 2020) but I've observed and experts confirm that prolonged exposure to any odor can desensitize people who may then no longer report the odor. That does not mean MVOCs are not presen nor would the absence of odor mean that a building is "safe" from mold or other contaminants.

MVOCs can be harmful, even toxic, particularly to people who are at extra risk of respiratory illness, asthma, mold allergies, etc.

The U.S. NIH defines MVOCS as

Microbial volatile organic compounds (MVOCs) are a variety of compounds formed in the metabolism of fungi and bacteria. (Korpi 2009)

Some MVOCs may be toxic, not just allergenic, and Bennett has suggested that we might characterize some MVOCs also as "mycotoxins". (Bennett 2015).

In general VOCs are carbon-compounds that are mixed into air from sources that evaporate easily at typical indoor temperatures. (Bemmett 2-15)

A mycotoxin is a toxic chemical that is found some mold spores or other physical material from growing mold, such as fungal hyphae or fruiting bodies (some, but happily not all "mushrooms") Mycotoxins may be present in moldy food as well, occurring both naturally and as contaminaints. (Bennett 1987, 1990)

The U.S. NIH defines

Mycotoxins are secondary metabolites produced by microfungi that are capable of causing disease and death in humans and other animals. (Bennett 1987)

On 2019-12-19 by lorie - clarify mycotoxins versus mVOC's?

Can you clarify mycotoxins versus mVOC's? Do molds emit BOTH toxins (called mycotoxins) AND volatile organic compounds (called mVOCs).

Or are the words synonymous? Your site is the closest I've come to finding that answer. Thank you!

On 2018-09-21 by Songbird

Thank you so much for your time and effort. It seems that without a time machine and proper testing equipment, there's just no way of knowing. At least I've got a little more information and clarity than before. Once more, your service is invaluable. This website is a godsend. I really appreciate it very much. God bless us all!

On 2018-09-21 - by (mod) -

Song

Your questions are reasonable but not possible to answer in any quantitatively-accurate way from the data you have.

If you smell mold there is mold nearby - though there can also be mold nearby that you don't smell as the release of MVOCS, as is the release of airborne mold spores, even for the very same mold genera, species, and strain, will vary by many factors such as what the mold is growing on (what it has to eat), indoor humidity and temperature variations, air movement variations, even changes in barometric pressure.

An acute exposure would be expected to cause a reaction in minutes if a person is sensitive to MVOCs;

Either acute or chronic exposure can, however, sometimes cause a person to develop sensitivity to mold even if they were not sensitive before.

These are questions to discuss with your doctor from a point of view of your current health and health complaints.

But without objective data it is very speculative to offer any guesses about what may have leaked into your occupancy space from an adjoining one, with the accurate truth ranging from nothing to something significant.

On 2018-09-21 by Songbird

Thanks for your reply, we spend most of our time in that room it's our bathroom which also shares space with our sleeping room. The exposure was for 2 12 hour shifts when the fan was left drying overnight.

At this point, I'm just trying to get a general idea as to what we might be on the lookout for health wise over the course of the next few years. Of course, it's uncertain at this time as to the exact level of exposure. By looking at my lab results, it might be safe to say those were some of the species we had sprayed our way.. but to what extent do these organisms travel through leaks in walls?

Would we be sick right away or would it happen later...so hard to find this stuff out on the web.

No doubt we were negligently exposed to something..I just don't know to what extent I should worry and take precautions as far as medical care. Thanks anyways..

On 2018-09-18 - by (mod) -

It's possible to determine the level of mvocs in a specific building area, at the time or during the interval of the measurement itself, but you certainly can't estimate the human exposure without a lot more data including levels at different elevations in a room over different times and of course more information about the amount of time that people or person spend in that environment.

On 2018-09-18 by Songbird

Hello, with this information , can you givee an idea of the level of exposure that might've occured?

On 2018-09-17 by Songbird

Maybe this information will help. This person, is an owner/operater of a franchise. He boasts 3 certificate logos on his website from ACAC and Internachi. I called to check his status, he has none. He is not certified. He did not use a special fan like you described. It was a regular high powered ordinary fan, the kind you would use to dry a carpet with. The stachybotrys mold was festering for at least 2 years and possibly much longer based on the history of previous owners.

The water source was from under the toilet , sewage pipes. The smell coming through to our side was very,very strong. This was after he had finished the removal of the mold. He used a green biocide. The musty/moldy smell was stronger at the electrical outlet.

Yes, I put my nose up to it...then taped it off. The fan ran overnight. No answers were provided when I called to report md ask if we should vacate. The landlord has failed to disclose other very worrisome material facts and has turned out to be of no help at all when I expressed my concerns over the incident.

He's harrased and threatened to evict and the list goes on and on. Further investigation revealed some shocking discoveries around this place where water damage, termite colonies and mold growth have been observed and I suspect the entire bldg in infested with various molds based on my findings.

As I looked around, pulled back carpets etc. I was shocked at what I saw in my apt. 3 days after the incident I noticed some weird stuff growing on my ceiling fan blades that didn't look likely usual dust. I had cleaned them only a few weeks ago. It seemed too much for the short time...I paid for an environmental company to take some surface samples. The fan blades had alternaria, basidiospores, cladosporium, hyphae fragments, misc unidentifiable spores, myxomycetes, pithomyces, and in trace amounts.

The wall where my window is where a termite colony burst through the window sill when I first moved in, had very high levels of ulocladium, hyphae fragments and chaetomium, and a lot of frass. The tackstrip on other side of room under carpet had moderately high aspergillus/penicillium, chaetomium and hyphae fragments. The surface of same carpet had basidiospores (slime mold?) and report that stated abnormal spore composition.

Stachybotrys was also where the frass was, but in trace amounts. This bldg was made in 1965. None of the previous owners took care of it, mold reports ignored and neglected, mold adenndum states no mold or water damage known here..outside the bldg are sign of obvious repairs of water and tree damaged walls. There's an active leak along seem and cracks all throughout.

So, how's that for more information! I haven't allowed my asthmatic daughter to be here ,period, not knowing the dangers to her health since this has all been exposed. Your website and feedback is invaluable to me. I have learned a lot of important information.

hank you for doing this. I'd like to know what you think about my surface samples results. So you think the fanblade is normal? I don't. I only could afford a few samples, I can only imagine what else is lingering.

I don't know I'm safe to remain here, as it stands I'm sealed off to just one room, I don't go in there except very briefly. I really need to understand just what that smell was blowing through our wall, the likelihood of inhalation of spores passing though various crevices and fixtures, as well as what other potential microbial creatures that might've come along when the toilet flange blew open from that fan..

if the mold was removed, why would such a strong odor be present the whole 12 hours it was running! 2 yrs worth of growth, if not much more...I doubt removing 4 feet of drywall is gonna take care of the problem. It was a traumatic experience and from what I've read on this awesome website, I should've called 911.

Thanks again for what you do here..your service is priceless.
Much appreciated.
Songbird

On 2018-09-17 - by (mod) -

Song

I'd like to help but I can't give any accurate assessment of the conditions that you would describe. There's just too many important considerations that one would have to see by an on-site inspection.

However it might be useful to understand that the air machines that are normally used during a mold cleanup or remediation project are designed to create negative air pressure in the workspace. That means that the fan vents to outside and would be more likely to draw air from any leaks on your side of the common wall rather than to push air into your space.

On 2018-09-16 by Songbird

A question about the passage of various m-vom, toxic mold spores, and other hazzardous organisms during remediation on opposite side of 4 in connecting wall. The water source for the mold, which has been festering for minimum 2 yrs, was from underneath the toilet in the sewage pipes.

The wall separates the bathrooms in an apt bldg. A high powered fan was used overnight and the smell..post mold removal, was very strong..a musty moldy smell.

The smell was stronger at the electrical outlet. The fan blew open the toilet flange as well. It was probably less than 2 feet away from wall..and it was a high powered industrial fan. What is the likelihood of various hazzardous substances contaminating iaq to the occupants on the other side of the wall?


...

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