Defining a Normal Fungal Ecology
November 20, 2007
Q: What is a “normal fungal ecology”?
A: “Normal fungal ecology” is a term that was arrived at by consensus while developing the First Edition of the IICRC S520 Standard and Reference Guide for Professional Mold Remediation. It was intended to describe an indoor environment that was not contaminated.
The S520 defines these three conditions:
Condition 1 (normal fungal ecology): an indoor environment that may have settled spores, fungal fragments or traces of actual growth whose identity, location and quantity are reflective of a normal fungal ecology for a similar indoor environment.
Condition 2 (settled spores): an indoor environment which is primarily contaminated with settled spores that were dispersed directly or indirectly from a Condition 3 area, and which may have traces of actual growth.
Condition 3 (actual growth): an indoor environment contaminated with the presence of actual mold growth and associated spores. Actual growth includes growth that is active or dormant, visible or hidden.
Contaminated (contamination): the presence of indoor mold growth and/or mold spores, whose identity, location and quantity are not reflective of a normal fungal ecology for similar indoor environments, and which may produce adverse health effects, cause damage to materials and/or adversely affect the operation or function of building systems.
You might note that Conditions 2 and 3 are “contaminated” and that Condition 1 lacks the same term in its description. All three terms should be understood in light of their being or not being contaminated.
Writing a standard has many unanticipated problems. When discussing an uncontaminated or clean environment, there was concern about the meaning of “clean.” Clean does not always mean the same thing to everyone. To some, clean means that the appearance is acceptable and it does not have an odor, but does that mean it is uncontaminated? Not necessarily. After cleaning, it might be assumed to be clean. The only way to determine whether it is uncontaminated is to test or sample the surface. There was some concern that the S520 would overstate what clean meant. In other words, it could be interpreted as meaning that the surface was free of molds or mold spores. Such a conclusion would lead to excessive remediation efforts and unnecessary additional costs. Since molds are ubiquitous, it was recognized that any environment will have some molds or mold spores present, at a level below that of a “contamination.”
The S520 Consensus Body was attempting to carefully and accurately describe an uncontaminated indoor environment, recognizing that such an environment has variability with respect to the types and quantity of molds present depending upon its unique circumstances. Therefore, a Condition 1 area may have settled spores, fungal fragments or traces of actual growth that is not reflective of a contaminated environment.
There has been criticism over the term “normal fungal ecology” because it does not clearly state what a “normal fungal ecology” is in terms of kinds or quantities of molds or mold spores that would be present. The Consensus Body never intended to quantify or definitively define what a “normal fungal ecology” is or was. The Consensus Body recognized the need for an indoor environmental professional to assist in making that determination. Notice what is stated in the S520 Preface:
S520 is not intended to establish procedures or criteria for assessing mold contamination in an indoor environment. These issues are most appropriately addressed by professional organizations that represent Indoor Environmental Professionals (IEPs). Since these professional organizations have not agreed upon threshold exposure limits or levels of visible mold growth that constitute a concern for occupant and worker safety, the IICRC Mold Remediation Standard Committee decided not to establish action levels or procedures based upon the quantity or size of the area of visible mold growth.
This statement was printed in the Standard in bold type to draw attention to the statement. The same problem exists with the term “normal background levels.” What is that? Each environment is unique and therefore an appropriate sampling strategy by an IEP is needed to determine what the normal or acceptable fungal condition for that specific environment (a “normal fungal environment” or “normal background levels”) happens to be. Also, there has been a criticism over the use of the term “ecology” since it could refer to the molds’ surrounding environment instead of an occupants’ surrounding environment. The interpretation depends entirely on a person’s perspective. In this context it refers to our surrounding environment where we live, work and exist.
The English language is sometimes difficult to master. Words and phrases can mean different things depending upon their context. The environmental community uses terms that are likewise hard to understand, such as viable or non-viable sampler.
A non-viable sampler does not collect only non-viable spores or particles, nor is the term “non-viable” meant to be interpreted as meaning this type of sampler is not practical or not workable. In reality, the term non-viable sampler means the sampler is not used to collect spores for the purpose of culturing them. It means nothing more and nothing less.
The S520 Consensus Body met and discussed these terms many times over a couple of years. There were participants from various industries that helped to develop the language. At one particular meeting a number of participants were asked to form a separate Ad hoc committee that met independently. They were instructed to create language that best described a remediated or uncontaminated building, system and contents. As I recall, the committee included several PhDs (Chemical Engineering; Public Health; and Microbiology), a CAIH, a California-EPA Registered Environmental Assessor, an environmental consultant and two remediators. The language changed many times in an attempt to be clear. However, the language needs to be considered in light of the entire document, not out of context. Because of the variability in each environment there cannot be a black and white statement that defines a “normal fungal ecology”.
Recently, a member of the IEQuality Yahoo discussion group made the following comment:
“It’s practically impossible to clearly define what is considered to be “normal” on a specific building material in [a] certain type of building at its own age located in each climate regions.”
The comment is absolutely correct. This is the very reason why the committee did not further define the term or the condition. The committee knew, or at least hoped that when it decided to use the term “normal fungal ecology,” it would move the IEP community to address the issue.
In a recent article entitled The 2006 Winter Solstice and the Future of IAQ, Dr. Bob Brandys, President of Occupational and Environmental Health Consulting Services Inc., stated that:
“The creation of the concept of “normal fungal ecology” was a brilliant first step in acknowledging that mold spore levels in the indoor environment are never zero. But what exactly is “normal fungal ecology” in buildings? We could surely use a better scientific delineation of this concept.”
Dr. Brandys’ approach was to try to understand what the S520 Committee was attempting to say and then to seek a solution. I personally hope that the indoor environmental quality (IEQ) industry does help to establish a “better scientific delineation of this concept.” That is where the definition of what a “normal fungal ecology” should come from.
Author’s Note: The viewpoints presented in this article are my personal opinions and not an official position of the IICRC, the IICRC S520 Consensus Body, the S520 Edit Committee, or the IICRC Standard Committee.