Are ERMI Scores from a Mold Inspection Helpful?
JW Biava
January 27, 2020
mold testing

Methodologies That Do Not Address Home Health Issues

Including Thoughts from Industry Expert, Dr. Joe Spurgeon

by Cesar Collado

In the past, I have written articles inspired by dialog with Dr. Joe Spurgeon regarding Physician Referrals for mold patients. Most recently, we collaborated on the discussion of some methods of testing used by “Mold Inspectors” and limitations of some of these approaches. To begin, I would like to share his philosophy regarding the purpose of mold inspections for mold patients specifically rather than only addressing water damage.

There are ‘two primary objectives’ when conducting mold inspections: Assessing Building Contamination and assessing Occupant Exposures – different objectives that may require different methods.  In general, those who understand building inspections have never been taught how to assess occupant exposures.  Many ‘inspectors’ have mentioned that they simply do not assess occupant exposures because they don’t know how.  This is a rational decision, but it’s a limitation that needs to be disclosed to the client.

– Joe Spurgeon, PhD.

About Joe Spurgeon PH.D. Dr. Spurgeon has a multidisciplinary doctorate degree in Analytical Chemistry and Environmental Health from the University of Pittsburgh; and was a Certified Industrial Hygienist from 1993 – 2013. He has been practicing in the Environmental Health sector for over four decades in a variety of capacities. 





His career has included:

  • Working with several US Govt. Health Agencies including US PH&S, EPA, CDC, ATSDR, FAA, and NIST
  • Licensed Class A general contractor, residential builder
  • Recognized Author on the topic of mold testing and interpretation []
    • The Collection and Interpretation of Indoor Mold Samples: A Comparison of Methods (2015);
    • Toxic Mold in Your Home: A Guide for Consumers (2015)
  • He has performed over 4,000 residential and commercial investigations involving water intrusions and microbial contaminants
  • He has taught courses on mold investigations, sampling, and data interpretation methods;
  • Expert witness in numerous mold cases.

Dr. Joe Spurgeon also has a sincere personal interest in the health effects of mold dating back to the 1980s when as a builder/contractor he was exposed to moldy drywall and was hospitalized for four weeks with a serious lung infection (Aspergilloma).  He has also pursued advanced training in Environmental Health, Toxicology, Exposure Assessments, Laboratory Analysis of Fungal Spores, Indoor Air Quality,  Health Care Facility Courses, and Asbestos Testing.   He has spent many years assessing mold exposures in homes, offices, and hospitals. Currently, he serves as an informal advisor to many environmental health specialists.

We recently collaborated on a white paper addressing a specific request from an environmental health consultant who had encountered the use of ERMI testing by mold inspectors as a tool in residential inspections.

Below is our collective response to the environmental specialist.

ERMI History

In 2007, EPA and U.S. Department of Housing and Urban Development researchers capitalized on Mold Specific Quantitative Polymerase Chain Reaction, MSQPCR, as a way to objectively describe the mold burden present in populations of homes. They then developed an index to determine “relative moldiness” in homes.

Figure 1. The percent of US homes versus ERMI values.

While PCR is a tried and true method for identifying specific mold, MSQPCR does not improve on the accuracy of current methods for identifying mold used by the mold inspection and remediation industries because of the lack of specificity and practical identification of the source of dust samples.  Current tools such as spore traps, mold gravity plates, bulk samples, and a qualified lab technician with a microscope are accurate and can be traced to the specific areas discovered or sampled.

ERMI was Intended to be a Research Tool Only

The term “Research Tool” is of particular importance.  Research tool methodology is used to gather large amounts of data from large populations in order to statistically determine accurate observations of a population.  Popular data collection methods include observation / participant observations, surveys, interviews, focus groups, experiments, and secondary data analysis / archival study or a combination of some of the above. The data is then evaluated using statistical methodologies to identify statistically valid observations.  The results provide predictive tools versus diagnostic information.

ERMI was specifically meant to observe dust samples for analysis from large populations of homes or buildings to determine high level observations of potential water damage.  The control of the experiment is a sampling from outside the dwelling.  Comparing the mold from the dust samples inside compared to control can help researchers draw high level conclusions about the moldiness of clusters of homes.

ERMI Usefulness in Home Inspection

A positive ERMI test is not particularly useful in a home inspection because dust sampling is not representative of specific places or causal conditions that contributed to the mold growth.  This includes water intrusion in homes and plumbing leaks or moisture problems contributing to systemic mold in the home.  Without a very specific investigation of the entire home, fixing the specific mold growth problem(s) in a manner that assures they do not come back is most likely impossible.  Specific samples and their sources are required to determine conclusive results for any particular section or source of mold in a home.

ERMI Testing Misapplications in Home Inspections

EPA designated ERMI testing as a research tool only; however, the EPA provided licenses to private industry to use the tool.  Unfortunately, some licensees have capitalized on the EPA legitimacy and have promoted ERMI as a technology innovation in home inspection. It is not uncommon for a patent or license to be used in ways that were not contemplated at the time of issuance or agreement.  Consumers sometimes believe the EPA development as a source of validation for the methodology.

Problems with ERMI Use in Home Inspections

ERMI Scores are most often applied to carpet dust samples; and ONLY to those carpet dust samples collected using a vacuum method. The application of ERMI scores to other surface types, or using other sample collection methods, may result in misleading interpretations.

Additionally, the high ERMI cost per sample often dissuades the collection of multiple samples. Statistically speaking, the more samples collected the higher confidence that a problem has been identified. Additional sampling also assists in determining what areas of the home are contaminated and where the mold contamination may be located.

Based on experience and that of my ImmunoLytics colleagues, ERMI is “too small” of a fishing net. ERMI only analyzes for a few of the thousands of species of mold. Additionally, its interpretation includes subtracting Group II molds from Group I to determine the score. However, the Group II molds are medically important and should not decrease the perception of an environmental hazard. As an example, Alternaria is one of the most antigenistic molds (super antigen that can cause auto-immune reactions) and produces serious health effects. ERMI does not associate Alternaria with water damage, and therefore subtracts it out of the total score. Candida is another health concern but is not included in an ERMI test. The list goes on and on.

The correlation of ERMI scores and health effects is non-existent, and there are an unacceptable number of both false negatives and false positives.

Back to Basic Mold Inspection Objectives for Mold Sufferers

When a patient is suffering from environmental illness, a mold inspection is performed with two objectives: 1) Identify mold, moisture source(s), and contaminated building materials and furnishings that serve as nutrients for the mold. 2) Assessing Occupant Exposure.  This is critical as identification of the specific mold exposure will provide valuable information to the treating physician in order for the patient to get well.

Unfortunately, the proliferation of the use of ERMI Index scores has spread to physicians in some cases.   For example, some physicians recommend that an acceptable ERMI score for sensitized patients with Chronic Inflammatory Response Syndrome [CIRS] is +2 or less. This criterion includes 60% of homes in the United States. However, only 40% of the homes that were included in the initial ERMI study had an ERMI Score higher than +2.Therefore, the research tool conclusions are too broad for individual home application. Consequently, specifying an ERMI Score of +2 or less for sensitized patients is not an appropriate screening parameter.


Use of an ERMI test in a home mold inspection should be viewed as a red flag that the inspector is using a research tool improperly in an application where it is not intended.  I suggest finding a mold inspector who utilizes existing tools that are better suited for assessing potential exposure.  This includes microbial identification (spore trap, gravity plate, swab sampling, tape-lift sampling, bulk sampling, etc.), by microscope or MSQPCR, or a combination of these methodologies.

ImmunoLytics Mold Testing

While Dr. Spurgeon pointed out that mold test plates seem to have limitations, he did not disagree that they are a valid method of testing for mold.  Mold test plates are conclusive as the petri dish incubates and grows the mold over time.  The mold growth can then be analyzed using microscopic identification.  There are other methods that collect air samples using more accurate collection methods.  There are also more precise tools employed by mold inspectors using MSQPCR samples; however, for DIY mold testing, gravity plates present a snapshot of the mold contamination with an accurate identification of specific molds that exist in your home.  This method is cost effective, accurate, and provides ample information to determine whether there is potential for mycotoxins.

ImmunoLytics Swab Test Kits

When mold is visible and/or difficult to sample with a test plate, the ImmunoLytics swab test kits can be ordered by simply scrolling down on the order page.  The swabs have an absorbent microfiber tip that will gather substantial samples for laboratory analysis.  Again, this approach has been used for decades and will yield accurate results for the DIY home-dweller.  The ImmunoLytics sample report will provide mold genera results with descriptions of potential mold metabolites that are toxic.  Other testing methods will also provide mold genera results.  Separate testing is required to accurately identify specific toxins when using any method.

Gravity plate reports can provide health care providers and mold remediators accurate information and evidence to develop treatment and remediation plans to get a patient, and their home, well and safe for continued healthy living.


  1. Report: Public May Be Making Indoor Mold Cleanup Decisions Based on EPA Tool Developed Only for Research Applications Report #13-P-0356, August 22, 2013
  3. The Environmental Relative Moldiness Index: A Research Tool Fact Sheet
  5. Spurgeon, Joe, Ph.D. “Assessing Occupant Exposures Using ERMI* Scores.” Dec 19, 2019