The Dead Mold Myth

Bleach

The question gets asked often. What do we tell customers who have either read or been told that “dead mold” can still make you sick. To answer this and other misconceptions, let’s dive into the history of the industry and my opinion as to how this whole thing got started. For many years, the general population was under the assumption that bleach killed mold. This can be traced to the 60’s or even earlier. A few years later, actually in the 70’s, changes in building techniques were instituted which made mold more and more prevalent in homes. At this point in the timeline there is an increasing mold problem throughout the country. People are bleaching mold and still feeling sick in their own homes after bleaching.

Other Chemicals & Spore Load

Along with this, home improvement establishments begin offering chemicals that control mold- but certainly nothing that kills the mold or effectively reduces the home's mold and spore load. This spore load of the home often remains high, even after much demolition has been done. The spore load of a home only goes up, not down, unless those spores are dealt with in the entire home.

One needs to read the small print to discover nothing is really being killed. The offering of these "Mold killing" chemical created a perfect storm. Mostly well meaning disaster recovery companies (and some not so well meaning) began the process of educating and selling the notion that even dead mold makes you sick so we need to tear out as much as possible to get the home safe. This multi million and perhaps billion dollar industry was created based on the perceived knowledge that even though people “killed” the mold with either bleach or some other disinfectant, some or all who lived in the home were still sick. The industry, to this day, hangs their hat on the idea that dead mold makes you sick. It is actually quite senseless if you really sit back and think it through. Now flash forward to somewhere in the late 90’s when it became obvious to some health practitioners, and some labs alike that bleach did not kill mold. This was huge news- yet nobody hit the reset button and set the record straight. Meanwhile, tear-out business is thriving, and in my opinion, compromising the health of every customer that tries to tear it out on their own or hires someone to do the same.

Lab data & Expert Opinions

Most still operate under the thought process that we think we killed all the mold, but someone was still sick. Therefore we need to tear out as much as possible. There is no testing data, no white paper, or anything that scientifically shows that a dead mold spore can either A- make you sick or, B- become an allergen. Yet the myth remains alive, based on 1) bad information dating back to the 60’s and based on 2) a few controlled lab studies out that use the pin-prick method. This is a method where they carefully extract a specific protein from a live mold spore in a closely controlled environment and prick it into a persons' skin. Much different than the oxidation process used by Pure Maintenance where the proteins are unraveled. More on that process below.

Don't believe us, listen to the experts. Dr. Harriet Burge is EMLab P&K's Director of Aerobiology and Chair of EMLab P&K's Scientific Advisory Board. Widely considered the leading expert in indoor air quality (IAQ), Dr. Burge pioneered the field more than 30 years ago. She has served as a member of three National Academy of Sciences committees for IAQ, including as Vice-Chair of the Committee on the Health Effects of Indoor Allergens.

“The medical community often misstates that they use dead mold for “Skin Prick” Testing. This is not accurate; they use a protein carefully extracted from a closely controlled live mold spore. It is not a dead mold spore, nor does it have the potential to be a biologically respirating spore. It is simply a specific protein from a mold spore that will mimic interactions of an actual live spore. These cultured proteins render “Skin Prick Testing” credible and effective.

Skin prick testing for mold allergies uses extracts derived from molds, not whole live spores or dead mold spores. These extracts contain the specific proteins from the mold that trigger an allergic reaction in sensitive individuals.
Here's why this is important:

• Allergens are typically proteins: Allergic reactions are triggered by specific molecules, often proteins, present in allergens like mold spores, pollen, or pet dander.
• Extraction focuses on relevant components: Extracting the proteins allows for a more controlled and standardized test. Manufacturers carefully extract these allergenic proteins from cultured molds.
• Not live spores: The extracted proteins are not capable of reproducing or spreading like live spores. The extracts used in testing are filtered and prepared to ensure sterility and safety.
• Safety and accuracy: Using standardized extracts helps ensure the accuracy and reliability of the skin prick test. This method allows doctors to assess a patient's sensitivity to specific mold allergens.

In summary, while the medical community may sometimes simplify the explanation by saying they use "mold" for testing, the actual practice involves using carefully extracted and purified proteins from mold to perform skin prick tests. This allows for a safe and effective way to diagnose mold allergies.”

The Answer

Pure Maintenance uses peracetic acid (PAA) in a dry fog format which acts a mold oxidizing agent. The mode of action is not just antimicrobial—it’s disruptive at the cellular and molecular level, as follows:

1. Cell Wall and Membrane Attack

• PAA is a strong oxidant that reacts with sulfhydryl (-SH), disulfide, and other reactive bonds in the lipids and proteins of the fungal membrane.
• This causes structural breakdown, increasing permeability and leading to lysis (bursting of the cell).
• Oxidative lysis here is rapid and thorough, unlike in lab studies where preservation of protein structure is critical for antigen analysis.

2. Protein Denaturation

• Once the membrane is breached, intracellular proteins—including allergens—are exposed to PAA.
• These proteins are chemically altered or denatured via oxidation, potentially rendering them unrecognizable to the immune system.
• The definition of denaturing is: destroying the characteristic properties of a protein or biological macromolecule by heat, acidity, or other effects that disrupt the molecular conformation. Once mold has been exposed to the fog, the outer membrane is oxidized and the cell is denatured. It becomes inert nothingness.

3. Organelle & Metabolic Collapse

• Organelles like mitochondria also suffer oxidative damage, leading to apoptosis-like cellular death.
• This contributes to rapid cell death, rather than a slow degradation pathway.

4. DNA/RNA Degradation

• DNA is more resistant to oxidation, but prolonged exposure or accumulation of ROS (reactive oxygen species) can fragment or mutate it (e.g., via 8-oxoguanine lesions).
• This matters less from an allergenic perspective—DNA is rarely the allergen.

All of this information is recognized by EPA registration documents for PAA-based biocides, academic and biomedical sources on oxidative biocides, and microbiology & mycology textbooks.

Another facet of this subject is the confusion between dead mold spores and dormant mold spores. Yes, dormant mold can still make you sick and dormant mold can still be an allergen. Think of dormant as “dehydrated” or dried out mold. Once it is exposed to the right environment, it’s off and running again. The dormant cell is still in-tact. But dead mold is a whole different thing. Dead, according to the microbiological world definition of dead, is accomplished by oxidative lysis. The outer membrane of the cell will fall apart through a process of oxidation. Proteins are unraveled.

Independent Data

Of course, we wouldn't expect you to take our word for it. Pure Maintenance carried out a study with the US Army Corps of Engineers to demonstrate the efficacy of the process outlined above. The purpose of the study was as follows:

"The objective of this ITTP demonstration was to conduct independent performance testing of the novel dry-fog mould remediation and prevention process to determine the effectiveness of the treatment process at eliminating mould and preventing regrowth at military installations and contingency basing locations." Below is a snapshot of some of the results from the study.

The dry-fog treatment was successful in reducing and maintaining mould at below background levels over the 6-month demonstration period. Figures 21 to 23 show the results of air sampling and surface sampling at Bldg. 2261.

Figure 22 shows that the total spore count weighted across all air sampling locations associated with Bldg. 2261 decreased from 64,126 spores/m3 before treatment, to 3,067 spores/m3 at 6 months after treatment. Over this same time period, the outdoor/background total spore count increased from 590 spores/m3 before treatment, to 19,000 spores/m3 at 6 months after treatment. Simply put, while the outdoor/background total spore count increased by 3,120%, the indoor (i.e., treated space) total spore count decreased by 95.21%.

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