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

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 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. 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 antifungal 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.

Where's the mold smell or musty odor problem source? 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.

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 detector-tubes and Drager accuro™ bellows pump, the Gastec™ cylinder pump and detector-tube system produced by Gastec or Sensidyne, and we also use Sensidyne's Gilian air pump. 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 Sampling Plan online document.

Our Indoor Gas Sampling Plan for Residential Buildings 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

Mold sniffing dogs are unreliable, though 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. What is the dog smelling? MVOCs.

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 are short as dogs go - and are not good at sniffing out MVOC's that telltale a mold problem high in a building wall or in a ceiling.

Beagles are cute, though.

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• Mold Prevention Strategies and Possible Health Effects in the Aftermath of Hurricanes and Major Floods, by
  Mary Brandt, PhD,1 Clive Brown, MBBS,2 Joe Burkhart, MS,3 Nancy Burton, MPH,3 Jean Cox-Ganser, PhD,3 Scott Damon, MAIA,2 Henry Falk, MD,4 Scott Fridkin, MD,1 Paul Garbe, DVM,2 Mike McGeehin, PhD,2 Juliette Morgan, MD,1 Elena Page MD,3 Carol Rao, ScD,1,5 Stephen Redd, MD,2 Tom Sinks, PhD,2 Douglas Trout, MD,3 Kenneth Wallingford, MS,3 David Warnock, PhD,1 David Weissman, MD3
  1National Center for Infectious Diseases
  2National Center for Environmental Health
  3National Institute for Occupational Safety and Health
  4Coordinating Center for Environmental Health and Injury Prevention
  5Office of Workforce and Career Development
  US EPA - original source: cdc.gov/mmwr/preview/mmwrhtml/rr5508a1.htm - this document includes a discussion of MVOCs.
• Schleibinger H, Laussmann D, Brattig C, Mangler M, Eis D, Ruden H. Emission patterns and emission rates of MVOC and the possibility for predicting hidden mold damage. Indoor Air 2005;15:98--104.
• HHE Report No. HETA-98-0235-2836, North View Elementary School, Eva Hnizeo, PhD., Greg Kullman, PhD, CIH, Peng-Fei Gao, PhD, CIH, June 2001 includes a description of five unique microbial volatile organic compounds (MVOCs) were detected in the basement area during investigation of mold contamination at this elementary school in Clarksburg WV. Orignal source: cdc.gov/niosh/hhe/reports/pdfs/1998-0235-2836.pdf

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