A STUDY TO EVALUATE PRODUCTS USED TO KILL MOLDhlspaces.com/MoldStudyFlipbook/EvaluateMoldKillerProducts.pdf · a study to evaluate products used to kill mold and if using them effects

A STUDY TO EVALUATE PRODUCTS USED TO KILL MOLD

AND IF USING THEM EFFECTS THE ACCURACY OF TESTING FOR MOLD

BY DANIEL STIH, B.S.E., CMC, CIEC

HEALTHY LIVING SPACES

505.992.9904

H E A L T H Y L I V I N G S P A C E SIndoor Environmental Test ing & Solutions

3 6 9 M o n t e z u m a Av e # 1 6 9 • t e l e p h o n e : 5 0 5 . 9 9 2 . 9 9 0 4 • w w w. h e a l t h y l i v i n g s p a c e s . c o m

AbstractThis paper describes an experiment that was performed to evaluate the effectiveness of products sold as mold killers and mold stain removers. It was done to determine if using these products inhibits the effectiveness of using surface samples (tape-lifts) to test for mold after treatment. Surface samples (tape-lifts) are routinely used by consultants and mold inspectors to verify the effectiveness of mold remediation projects. Surface samples are used to verify the sur-faces are clean and do not contain actual mold growth. Some of these products may leave an invisible residue that acts like an encapsulation, preventing spores from being transferred to the tape. This may lead to the false conclusion that mold is not present when it is.

For the experiment, a mold contaminated utility closet in a home was used (Figure 1). Products were applied to keep surfaces wet for at least 10 minutes. Surface samples were taken before treatment, six hours after treatment and twenty-four hours after treatment (Figure 2).

Figure 1: Before Treatment! ! ! Figure 2: After Treatment

Based on an analysis of surface samples collected (tape-lifts), the conclusion is, that the use of products alone does not remove all the mold that is present and that the use of some products may inhibit the detection of residual mold. Some products encapsulate the surfaces altering the way mold spores transfer to tape. Use of some products may make it difficult to use tape lifts as they are traditionally used to test for the presence of mold contamination in a building.

H e a l t h y L i v i n g S p a c e s L L C ( 5 0 5 ) 9 9 2 - 9 9 0 4! S t u d y t o E v a l u a t e “ M o l d K i l l e r ” P r o d u c t s

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IntroductionTraditionally, mold remediation was performed by removing mold versus trying to treat or kill it. The New York City Department of Health was one of the first public health organizations to provide guidance on how to remediate mold. Created in 2000, much of the information contained in Guidelines on Assessment and Remediation of Fungi in In-door Environments was subsequently adopted by the EPA. According to these Guidelines, “Porous materials (wall board) should be removed and discarded. Cleaning should be done using soap or a detergent solution using the gen-tlest cleaning method that effectively removes the mold. Disinfectants are seldom needed because the removal of fungal growth remains the most effective way to prevent exposure. The use of gaseous or aerosolized (fogging) bio-

cides is not recommended.”1

Most professional mold remediators are familiar with the IICRC S520 Standard and Reference Guide for Professional Mold Remediation. It is ANSI standard that has been peer reviewed and is widely accepted and recognized in the industry. According to the S520, “Source removal of mold should always be the primary means of remediation. Indiscriminate

use of anti-microbials, coatings, sealants and cleaning chemicals is not recommended.”2 “Porous building materials (e.g., drywall, insulation, and ceiling tiles that are Condition 3 [Actual Growth] should be removed and discarded. Other materials that are semi-porous (e.g., wood studs) can be HEPA vacuumed and either wire-brushed or sanded,

the damp-wiped.”3

Since removing mold versus treating it can be expensive and time consuming, there are now products on the market that suggest they can provide a quicker turn around time. This eliminates removing the materials contaminated with mold or cleaning them by sanding or wire-brushing. This paper will study if they work (remove mold). This paper will also study if using these products inhibits the detection of any residual mold.

Traditionally, after a mold remediation project is completed, a consultant independent of the contractor performing the remediation work, performs testing to verify the mold has been removed. This testing may consist of a combina-tion of collecting surface and/or air samples. Surface samples are typically collected to ensure that the readily acces-sible surfaces are clean and clean of actual mold growth. Tape-lift samples are the preferred way of collecting surface samples (compared to a swab) as there is direct transfer of the particles and mold from the surface to the tape. Any residual particle matter and mold can easily be observed under the microscope without the need to culture. Unlike a swab which can damage the structure of the mycelium and spores that may be present, using a tape lift results in the most direct transfer of particles to the media for direct microscopic examination.

If the products used to treat mold leave any residuals or coatings, it may be difficult to obtain reliable surface lift samples. There is the potential that spores and particles present on the surface will not transfer to the tape (or swab). The significance of this is that the consultant doing the testing may conclude that all the mold has been removed when it in fact has not been.

Types of Mold Killers and Mold Stain Removers Evaluated

The first product evaluated (Product 1) is sold as a mold stain remover. It is sold in a package of two bottles, one that contains a dry powder substance; one that is a liquid. The two bottles are mixed together by adding them to warm water and applied using a spray bottle or by fogging. According to the Material Safety Data Sheet (MSDS) the bottles contain Arylesterase (<1%), Propylene Glycol Diacetate (48-52%), and Sodium percarbonate (47-51%). According to the MSDS, when mixed with water the product forms Peracetic acid (most likely by the oxidation of the acetalde-hyde).


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Some background information: the EPA first registered peracetic acid as an antimicrobial in 1985 for use on hard sur-faces. As an oxidizing agent sodium percarbonate is an ingredient in a number of laundry cleaning products. Dis-solved in water, it yields a mixture of hydrogen peroxide and sodium carbonate. Sodium carbonate, sold as washing soda, can be used to remove grease, oil and stains and as a descaling agent. Propylene Glycol Diacetate is typically used as a solvent or plasticizer. It hydrolyses to Acetic acid and Propylene Glycol when mixed with water. The manu-facturer has not disclosed what the purpose of the Propylene Glycol is.

The second product (Product 2) evaluated is a hydrogen peroxide based formula. There are two equal parts of liquid that are mixed together prior to use. It can be applied either by sprayer or by fogging. Product literature says it kills mold on contact and requires no invasive demolition. According to the MSDS, it contains Quaternary Ammonium Compounds (1.6%), hydrogen peroxide (3.98%; 1 ppm) and Inert Ingredients (94.42%). The exact type(s) of Quater-nary Ammonium Compounds are not listed. Quats generally act by disrupting cell membranes.

Some background information: the term “inert” does not mean non-toxic. While in chemistry the term inert is used to describe a substance that is not chemically reactive, for anti-microbials registered with the EPA, the term is defined by the federal law that governs pesticides, the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). According to FIFRA, where as an active ingredient is one that prevents, destroys, repels, or mitigates a pest, all other ingredients are called inert. Examples of inert ingredients may include those that related to foaming, extending product shelf-life, solvents used to penetrate, and ingredients that are generally used to increase the effectiveness of the active ingredi-

ents4.

The third product evaluated is a 3% solution of hydrogen peroxide obtained at a local drug store.

Methods & MaterialsA moldy mechanical room in a residential home was used (Figure 1). The back interior wall was observed to be cov-ered with mold to a height of approximately five feet. Conditions were dry at the time of testing. Figure 3 is a close up prior to treatment with Product 1; Figure 4, a close up prior to treatment with Product 2; Figure 5, a close up of the front of platform prior to treatment with 3% hydrogen-peroxide. The colored push pins are reference markers where surface samples were collected. Colored push-pins were also used to note the areas where surface samples were collected so that samples could be collected after treatments in approximately the same locations.

Figure 3: Prior to treatment with Product 1! Figure 4: Prior to treatment with Product 2 Figure 5: Prior to 3% Hydrogen peroxide.H e a l t h y L i v i n g S p a c e s L L C ( 5 0 5 ) 9 9 2 - 9 9 0 4! S t u d y t o E v a l u a t e “ M o l d K i l l e r ” P r o d u c t s

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Collecting Surface Samples (Tape Lifts) Prior to Treatments

Surface lift (tape) samples were collected before treatment. Surface tape lift samples were analyzed by direct micro-scopic examination by Healthy Living Spaces LLC and Los Alamos National Laboratories (LANL). Healthy Living Spaces is a participant is LANL’s Technical Assistance program. Unless other wise noted, the following microphoto-graph were taken by Healthy Living Spaces. Microphotographs of samples analyzed and taken by Los Alamos Na-tional Laboratories are noted with (LANL).

Figure 6 is a microphotograph (600X) of a surface sample (tape-lift) collected from the area on the right side of hot water heater prior to treatment with Product 1. Primarily Stachybotrys is observed to be present with a few Alter-naria type spores. Figure 7 is a microphotograph (100X) of a surface sample (tape-lift) collected from the area behind the boiler prior to treatment with Product 2. Primarily Alternaria type mold was observed. It should be noted that only a small portion of each surface is examined microscopically. There are likely to be other types of mold present than those identified in the limited surface samples that were collected. The locations for sampling were chosen ran-domly based on what appeared to areas with significant mold growth. The colored push pin was inserted after the samples were collected. Figure 8 is a microphotograph (600x) of a surface sample (tape-lift) collected from the area in front of the platform prior to treatment with 3% hydrogen peroxide. Primarily Stachybotrys was observed.

Figure 6: (600X) Tape-lift, before treatment! Figure 7: (630X, LANL) Tape-lift, before treatment Figure 8: (600x) Tape-lift, before treatment

Collected from area to be treated with Product 1. Collected from area to be treated with Product 2.! Collected from area to be treated with

! ! ! ! ! ! ! ! ! 3% hydrogen peroxide.

Applying (Spraying) the Mold with the Products

Plastic sheeting was used to partition the moldy closet into sections (Figure 9).

The products were mixed and prepared according to instructions on the labels. In one section Product 1 was sprayed (next to the right side of the hot water heater); In another section Product 2 was sprayed (on the left side of the boiler and behind the boiler); the 3% hydrogen peroxide was sprayed on the wall in front of the platform.

Surfaces were sprayed so that surfaces remained wet for at least 10 minutes. Surfaces were measured with a moisture meter and found to be damp (20%) six hours later.


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Figure 9: Plastic installed to isolate areas

Figure 10: Immediately after treatment ! Figure 11: Immediately after treatment ! Figure 12: Immediately after treatment with

Product 1.! ! ! ! with Product 2.! ! ! ! with 3% hydrogen peroxide.

Figure 13: Six hours after treatment ! ! ! ! Figure 14: Six hours after treatment with !

with Product 1! ! ! ! ! ! 3% hydrogen peroxide.


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Figure 15: 24 Hours after treatment ! Figure 16: 24 Hours after treatment ! Figure 17: 24 hours after treatment with Product 1.! ! ! with Product 2.! ! ! with 3% hydrogen peroxide.

Results & DiscussionThere is visible mold and staining present twenty four hours after the application for all the products tested. The sur-faces treated with Product 1 and Product 2 seemed to be less darker, less black than before treatment, probably occur-ring from the oxidation process. The surfaces treated with drug store 3% hydrogen peroxide did not have a signifi-cant color change.

In collecting surface samples from surfaces after treatment with Product 1 and Product 2, it was necessary to remove a portion of the drywall paper onto the tape to transfer the darker (mold) particles onto the tape. This was not the case for samples collected from the surfaces treated with drug store 3% hydrogen peroxide. The mold particles on those surfaces appeared to readily transfer to the tape similar to how they did before treating the surface.

Collection and Analysis of Surface Samples (Tape Lifts) After Treatments

Surface lift (tape) samples were collected six and twenty-four hours after treatments. It should be understood that the using of a tape lift to collect a surface sample typically removes much of the mold present on the surface where the tape is applied and removed. Therefore tape lifts collected after the application of the products, were taken nearby but not in exactly the same locations. Colored push-pins were used to note the areas where surface samples were taken prior to applying products, so that samples could be collected approximately near the pins but not exactly at the pins.

Figure 19 is a microphotograph (600x) of a surface sample (tape-lift) collected from the area on the right side of hot water heater after treatment with Product 1. The yellow hue is due to the presence of drywall paper. At first glance under lower magnification there did not appear to be much mold. There were some dark areas observed suggestive of mold embedded in the paper. Figure 19 is the microphotograph taken at higher magnification. Stachybotrys spores appear to be embedded in or mixed in with the paper. The spores appear opaque instead of dark colored probably because they were oxidized (bleached) by the treatment.


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Figure 20 is a microphotograph (100x) of a different surface sample (tape-lift) collected from the area on the right side of hot water heater after treatment with Product 1. Alternaria is the primary genera observed.

Figure 19: (600X) Tape-lift collected after! Figure 20: (600X) Tape-lift collected after ! ! ! ! !

treatment with Product 1.! ! treatment with Product 1.

The following three microphotographs were taken by Los Alamos National Laboratories (LANL) of samples ana-lyzed by LANL collected from the area behind the boiler after treatment with Product 1. Alternaria and other types are observed.

Figure 21: (630X; LANL) Tape-lift collected Figure 22: (630X; LANL) Tape-lift collected Figure 23: (630X; LANL) Tape-lift collected

after treatment with Product 1.! ! after treatment with Product 1.! after treatment with Product 1.

It was observed the the residual coating left by Product 1 and Product 2 appear to inhibit the transfer of particles to the tape lift samples. If one is not aggressive in collecting the samples (pressing hard and removing a portion of the paper from the drywall) mold remaining on the surface may not be transferred to the tape.The following is a micro-photographs taken by Los Alamos National Laboratories (LANL) of areas treated with product 1 that demonstrates how the mold particles cling to the paper fibers.

Figure 24: (630X; LANL) Tape-lift, collected

after treatment with Product 1.

Figure 25 is a microphotograph (100x) of a surface sample (tape-lift) collected from the area behind the boiler after treatment with Product 2. Note: the paper backing of the drywall came off with the sample. At lower magnification H e a l t h y L i v i n g S p a c e s L L C ( 5 0 5 ) 9 9 2 - 9 9 0 4! S t u d y t o E v a l u a t e “ M o l d K i l l e r ” P r o d u c t s

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there appears to be some mold contamination (dark spots). At higher magnification Stachybotrys spores are more readily visible embedded or mixed in with the paper. Figure 26: is a microphotograph (600x) at higher magnification of the same surface sample. Note the presence of Stachybotrys spores.

Figure 25: (100X) Tape-lift, collected after! Figure 26: (600X) Tape-lift, collected after ! ! ! ! !

treatment with Product 2.! ! treatment with Product 2.

Figure 27 is another microphotograph (600x) of the surface sample above (tape-lift) collected from the area behind the boiler after treatment with Product 2. Note the mold spores attached or embedded to the paper fibers. Alternaria is observed.

Figure 27: (600X) Tape-lift, collected after ! Figure 28: (600X)Tape-lift, collected after ! ! ! ! !

treatment with Product 2.! treatment with Product 2.

The following are three microphotographs that were taken by Los Alamos National Laboratories (LANL) of surface sample (tape-lifts) collected from the area behind the boiler after treatment with Product 2. Mold growth is visible in all of the samples.

Figure 29: (630X; LANL) Tape-lift, collected Figure 30: (630X; LANL) Tape-lift, collected Figure 31: (630X; LANL) Tape-lift, collected

after treatment with Product 2.! ! after treatment with Product 2. ! after treatment with Product 2.


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Figure 32 is a microphotograph (100x) of a surface sample (tape-lift) collected from the area in front of the platform after treatment with drug store 3% hydrogen peroxide with mold growth (spores and mycelium) obvious. Figure 33 is also a microphotograph (600x) of a surface sample (tape-lift) collected from the area in front of the platform after treatment with drug store 3% hydrogen peroxide. Stachybotrys is readily visible. There does not appear to be any re-duction in the number of spores or significant change in the spore structure (absence/presence of mycelium) or color compared to microphotographs taken of surface sample before treatment with 3% hydrogen peroxide.

Figure 32: (100X) Tape-lift, collected after! Figure 33: (600X) Tape-lift, collected after ! ! ! ! !

treatment with 3% hydrogen peroxide. treatment with 3% hydrogen peroxide.

The following microphotographs that were taken by Los Alamos National Laboratories (LANL) of surface sample (tape-lifts) collected from the area treated with 3% hydrogen peroxide. Mold growth is visible in all of the samples.

Figure 34: (100X; LANL) Tape-lift, collected Figure 35: (630X; LANL) Tape-lift , collected

after treatment with 3% hydrogen peroxide.! after treatment with 3% hydrogen peroxide.! !

Collection and Analysis of Swab Samples

Similar to how tape lift samples were collected, swab samples were taken before and twenty-four hours after the treatments. Swab samples were cultured for viable fungi using Malt Extract Agar (MEA) and Cellulose based agar. MEA is an agar generally used for the isolation of broad-spectrum fungi; Cellulose is used to isolate Stachybotrys. The swab samples were cultured and analyzed by EMLab P&K.

Table I and Table II show the results for cultures of samples collected before and after the surfaces were treated. The results are expressed in colony forming units (CFU) per swab. Each sampled area was approximately one square inch.

Based on laboratory results, there was nearly a 100% reduction in the viability of spores treated with Product 2. There did not seem to be as much of a reduction in the viability of spores for surfaces treated with Product 1 or 3% hydro-gen peroxide.


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For the surfaces treated with 3% hydrogen peroxide there was a significant amount of Stachybotrys in both the before and after samples cultured using Cellulose agar. The samples cultured using MEA agar showed a reduction in Stachybotrys and an increase in yeasts. The reason for this is unknown. If the bulk Stachybotrys spores were rendered non-viable after treatment, perhaps the yeast was able to thrive in the culture with less competition. In other words, although Stachybotrys was not rendered non-viable, perhaps its viability was compromised.

TABLE I. Viability of spores before and after treatments.Surface swabs cultured using Cellulose Agar. Surface areas approximately one square inch.

Colony Forming Units (CFU) per swabColony Forming Units (CFU) per swabColony Forming Units (CFU) per swabColony Forming Units (CFU) per swabColony Forming Units (CFU) per swabColony Forming Units (CFU) per swab

Product 1Product 1 Product 2Product 2 3% Hydrogen Peroxide3% Hydrogen Peroxide

Before After Before After Before AfterPenicillium 300 10,000Stachybotrys 110,000 1,000 170,000 540,000 770,000Ulocladium 600 10,000Total 110,000 2,300 200,000 ND 540,000 770,000

TABLE II. Viability of spores before and after treatments. Surface swabs cultured using Malt Extract Agar (MEA). Surface areas approximately one square inch.

Colony Forming Units (CFU) per swabColony Forming Units (CFU) per swabColony Forming Units (CFU) per swabColony Forming Units (CFU) per swabColony Forming Units (CFU) per swabColony Forming Units (CFU) per swab

Product 1Product 1 Product 2Product 2 3% Hydrogen Peroxide3% Hydrogen Peroxide

Before After Before After Before AfterAlternaria 3,000 10,000 22,000 10Cladosporium 4,700 10,000Penicillium 70,000 37,000 310Stachybotrys 680,000Yeasts 300,000 3,000Total 7,700 470,000 75,000 10 680,000 3,300

For the surfaces treated with Product 1 there appeared to be some reduction in the amount of viable Stachybotrys and an increase in yeasts and other organisms. Similar to the results for the 3% hydrogen peroxide, the reason for this is not understood. Perhaps the viability of the Stachybotrys spores was effected by treatment allowing other genres to thrive in the culture with less competition.

Viable results might not seem relevant to this paper because even if there is a reduction in the viability of residual spores, there may not be a reduction in the health effects and symptoms associated with mold exposure unless the mold is removed. According to the EPA, “Mold spores and fragments can produce allergic reactions in sensitive indi-

viduals regardless of whether the mold is dead or alive.”5


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ConclusionsIt is important to understand that this experiment is not comparing how brands of mold killers and mold stain re-movers perform relative to each other. What is being studied is whether or not these products actually remove the mold and if using these products may effect the validity of using surface (tape lift) samples to detect any residual mold.

While it might seem interesting to compare how many spores may have been killed by each product, the first ques-tion to consider is do the products eliminate mold such that the traditional methods of removing mold do not need to be followed. The products tested did not completely remove the mold that was present. Tradition methods of re-moval (physical removal) are still required to get rid of mold.

The use of some products may reduce the viability of some types of mold spores. There was a near 100% reduction in the viability of spores for surfaces treated with Product 2. There did not appear to be a significant reduction in the viability of spores for surfaces treated with Product or the 3% Hydrogen Peroxide. More testing is needed to make a definitive conclusion regarding the effectiveness of 3% Hydrogen Peroxide and Product 1 to reduce the viability or spores.

The use of products other than the 3% drug store hydrogen peroxide appear to encapsulate surfaces with a clear, mi-croscopic coating. The composition of the residual films are unknown. This is something that needs to be studied further.

The residual coatings left by Product 1 and Product 2 appear to inhibit the transfer of particles to tape lift samples. If one is not aggressive in collecting the samples (pressing hard and removing a portion of the paper from the drywall) mold remaining on the surface may not be transferred to the tape. The particles and mold spores that are collected may be obscured by the presence of the paper from the drywall. This sometimes prevented an analyst from observing residual mold that was present depending on how carefully the tape lifts were examined and how much particles transferred to the tape. The use of products therefore may inhibit the accuracy of testing for mold using surface sam-ples when certain products are applied. It is recommended that if products other than plain soap and water or 3% hydrogen peroxide are applied, they should only be applied after post-remediation testing is performed and the re-sults indicate the structure has been restored to Condition 1 [No actual mold growth] as specified in the S520 .

The use of drug store 3% hydrogen peroxide did not appear to effect how particles are transferred to tape. Samples collected from surfaces treated with 3% hydrogen peroxide appeared the same before and after the application of the hydrogen peroxide, although there might appear to be a slight browning effect on the spores due to the oxidation effect.

Health Living Spaces LLC and Los Alamos National Laboratories (LANL) plan to continue this research in 2013. Through cooperative effort, the intention is to repeat this type of experiment with additional types of products to be tested.


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AcknowledgementsLos Alamos National Laboratory (LANL) provided technical assistance to Healthy Living Spaces in the form of mi-croscopic analysis of mold samples and materials. This was done through funding by the New Mexico Small Business Assistance Program. LANL investigated the use of advanced microscopy techniques for the identification of spores using as many techniques as possible and practical. These included:

• Polarization Light Microscopy• Scanning Electron Microscopy • Atomic Force Microscopy• 3D Optical Microscopy• Raman Microscopy• Infrared Microscopy

During the course of the project, LANL employed the following microscopes:

• Carl Zeiss LSM510 Fluorescence and Optical Microscope (Optical)•Witec Alpha300 Atomic Force and Raman Microscope (AFM/Raman)•FEI Quanta 600 Environmental Scanning Electron Microscope (ESEM)•Olympus LEXT OLS4000 (3D Optical)•Varian FTIR microscope (IR)

For a copy of the Statement of Work and the final report, please contact Healthy Living Spaces. Of particular interest are the scanning electron microscope (SEM) images of mold on tape sample and the 3D Optical image of hyphae and spores shown at different angles.

Figure 36: SEM (LANL) ! ! Figure 37: SEM (LANL) ! Figure 38: 3D Optical (LANL)

Cover Photo: Los Alamos National Laboratories (LANL)


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About the AuthorAs President of Healthy Living Spaces LLC, Mr. Stih inspects residential and commercial buildings to identify building-related sources responsible for complaints and illness, includ-ing but not limited to mold. Mr. Stih, an aerospace engineer, retired from Motorola Inc. and worked in construction before bridging his engineering background with the building sci-ences to start an environmental testing and consulting company. His company has had of-fices in three states: Arizona, Oregon and New Mexico, which has allowed him to acquire experience working with mold and indoor air quality issues in different climates.

Stih’s experience with microscopy and microbiology dates back to 1978, when as teenagers, Stih and his brothers opened Sun Laboratorys in the utility room of their par-ents’ home. In 2010, he completed a 40 hour course, My-cology and Fungal Spore Identification, at the McCrone Re-search Institute in Chicago.

In addition to other certifications, Stih holds both a Council-Certified Microbial Consultant (CMC) and Council-Certified Indoor Environmental Consultant (CIEC) certi-fication, Board-awarded by the American Council for Accredited Certification (ACAC).


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References1. Guidelines on Assessment and Remediation of Fungi in Indoor Environments, New York City Department of Health,

2008. 2. ANSI/IICRC S520-2008 Standard and Reference Guide for Professional Mold Remediation, Institute of Inspection, Clean-

ing and Restoration Certification (IICRC), p.21, 2008.3. ibid., p.1734. Inert Ingredients Frequently Asked Questions, United States Environmental Protection Agency, Office of Chemical

Safety and Pollution Prevention, Washington, D.C., September 2012.5. Mold Remediation in Schools and Commercial Buildings, Appendix B - Introduction to Molds, EPA United States Envi-

ronmental Protection Agency, cited on-line, November, 2012.


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Documents

A STUDY TO EVALUATE PRODUCTS USED TO KILL MOLDhlspaces.com/MoldStudyFlipbook/EvaluateMoldKillerProducts.pdf · a study to evaluate products used to kill mold and if using them effects