Environmental Mold Testing

House Drawing

Is My Home Okay?

Most people who are living or working in buildings with even extremely bad toxic mold issues are totally unaware that there is any sort of a problem going on.

Even those who are very sick from the mold usually have no idea.

Toxic mold growth is often totally hidden in modern homes.

It often cannot be smelled.

Even when it can be seen, it often looks like a smear of dirt on the wall – thus causing many people to overlook the fact that mold is present.

Unfortunately, some of the most high-profile tests for toxic mold are not very accurate (and can cost a large amount of money besides).

Therefore, here is a brief rundown of some different options for people who are looking to determine whether their current environment is safe for them.


The ERMI Test

The most recommended test by mold illness doctors and specialists is the ERMI (Environmental Relative Moldiness Index).

This test was originally developed by the US Environmental Protection Agency (EPA).

It involves the examination of the proteins in a dust sample from the building for the genetic presence of 36 different mold species.

The ERMI report provides a score comparing the building in question to a variety of other U.S. buildings, with regard to the likelihood that it will be capable of causing harm to its occupants.

Although many experts believe that the ERMI does a generally good job in identifying really problematic buildings that are harming people, is not a perfect test.

It has a margin of error of +/- 3 points (which means that a building with a score of 0 and a building with a score of 3 should not be assumed to actually be any different from one another).

Sometimes the ERMI can miss major hidden mold problems entirely.

In addition, the ERMI does not test for environmental toxins. It tests for the species of mold that make the toxins.

Since many mold species can make a variety of toxins (some of them much worse than others) and also sometimes can be non-toxic, this introduces another element of inaccuracy into the test results.

The ERMI is a moderately priced test, costing around $200-300 depending on the laboratory.

The fact that it is a do-it-yourself test rather than one requiring the involvement of a professional also is appealing to many people.

Dr. Ritchie Shoemaker currently is suggesting a laboratory called Envirobiomics for this kind of testing.

Another popular ERMI test that has been recommended by many mold illness doctors is offered by Mycometrics.

Some additional laboratories offer ERMI tests at lower prices, but questions have been raised with regard to whether those tests are sensitive enough (i.e. whether the higher numbers of non-detectable molds reported impact the usefulness of the test results).



Dr. Ritchie Shoemaker says that he developed this test by looking at the ERMI scores of thousands of mold illness patients and determining which species of mold seemed to be most problematic for them.

The HERTSMI is the same basic genetic test as the ERMI, except that it looks for the presence of only five particularly dangerous species of mold – Aspergillus penicilloides, Aspergillus versicolor, Chaetomium globosum, Stachybotrys chartarum, and Wallemia sebi.

Testing for the HERTSMI is offered by Mycometrics or Envirobiomics at a cost that is substantially lower than the ERMI.

A HERTSMI score also can be calculated by looking at the scores of a regular Mycometrics or Envirobiomics ERMI test.

Dr. Shoemaker suggests that this test be used to evaluate potential residences by people who already know that mold is a problem for them, rather than to determine whether a suspect building is unsafe in general.

This test has yet to have any papers published about it and is not yet in widespread use, but some mold doctors and patients suggest that it has been helpful to them.


Air Tests

Air tests look for the presence of whole spores of different species of mold in the air at a particular moment in time.

Those evaluating the test results look at the amount of mold present, at the types of mold present, and at how indoor samples compare with outdoor samples.

These tests are almost always run by indoor air quality professionals rather than individuals.

They tend to be quite pricey, often costing $1,000 or more.

The main problem with air testing is that since it is looking only for whole spores that are floating in the air rather than at genetic material, it tends to miss certain species of mold.

For instance, perhaps the most problematic species of mold, Stachybotrys, is released from colonies into the air in waves.

Stachy also makes a heavy, sticky spore that falls rapidly to the floor and then usually breaks up into spore fragments, which are at least as toxic and dangerous as the whole spores.

These spore fragments mix with the other dust in the environment and get blown or carried all around the building.

As a result, Stachybotrys almost never shows up on air tests even when it is a major problem. Certain other molds may not come up either.

Possibly air tests may be helpful when allergies or asthma are the main issue, since knowing that toxic mold is present may be less important in those conditions.

Doctors and toxicologists specializing in toxic mold illness almost always suggest that air tests are not reliable enough to be used as a gauge of whether a building is safe for people with chronic multisystem illnesses, however.


Petri Dish Tests

Petri dish tests are relatively inexpensive test kits that can be bought at stores like Home Depot.

Petri dishes full of mold food are placed in suspect environments for a time so that mold can start to grow. They then are sent to a laboratory to evaluate how much mold and which species are present.

These test kits are inexpensive, usually costing between $10 and $80.

While mold of all kinds tends to grow on these dishes when a toxic mold problem is present, beyond that the results tend to be very difficult to interpret.

One reason is that some of the worst kinds of mold – including Stachybotrys – tend not to grow very well in the conditions in the dish.

Some people suggest that Petri dish tests have been helpful to them in proving to themselves or their landlords/employers that buildings have mold problems that need to be investigated further.

However, few toxic mold experts recommend them even for this purpose.


Tape Lifts

If mold is noted to be growing in an environment, then it is possible to take a tape lift sample and send it off to a laboratory to be identified.

While this may be interesting, getting back a report that the species of mold found in the home is a non-toxic one should not be taken as any kind of reassurance that a major toxic mold problem is not present.

Typically, toxic species of mold hide inside walls or air ducts, making poisons that act as antibiotics and change the microbial balance of the environment.

As  result of this, molds of all kinds have an easier time growing out in the open.

Therefore, the presence of any mold growing in an environment should be taken as a clue that a toxic mold problem may be present, even if the mold that is found turns out to be relatively non-toxic.


Moisture Meters

A problem with modern buildings is that major mold problems can occur in between walls without anyone knowing about them.

Typically, a leak or condensation inside the wall will allow mold to start to grow, using the drywall or insulation as a food source.

A moisture meter is used to identify sections of the wall that have a humidity level that is higher than expected.

That gives the mold professional a better idea of where to look in the walls for problem spots, so that water problems can be proactively addressed and so that any mold growth that has occurred can be dealt with safely.

Moisture meters can be very useful in finding leaks or other water intrusions.

They do not provide information on whether any mold is present, however.

Depending on the quality and functionality, they can range in price anywhere from $10 to a few hundred dollars.


Thermal Imaging

Thermal imaging (also called infrared or thermographic imaging) is a tool that identifies variations in temperature.

It is occasionally used by professionals when looking for places in walls where mold may be hiding.

Because moisture can alter heat patterns, this kind of device can be helpful in finding leaks or other water damage.

In addition, it may be successful at finding cold spots inside walls where condensation may be especially likely to be occurring on a regular basis.

Thermal imaging equipment can range in price from $30 to several thousand dollars.

An accessory that works with the iPhone also is available.


Visual Inspection

While the air tests that indoor air quality professionals often recommend can miss major mold problems, these professionals nonetheless often can be very helpful in locating potential problem spots that need to be examined further.

Experienced professionals have seen many buildings and frequently can easily pinpoint where mold problems are likely to be hiding.

Although the industry convention is to suggest that a mold inspector should not also be hired to do mold remediation work, this really comes down to a matter of trust.

No one would say that a physician who diagnosed  a need for a heart operation should not be allowed to perform that operation, for instance.

As an alternative strategy, some people struggling with apparent mold issues in their homes have reported hiring multiple professionals to do assessments and then choosing the one that they felt was the most trustworthy to do the actual remediation work.


The Mold Sabbatical

One strategy that many people have used to determine whether their home or workplace is problematic for them is by pursuing a mold avoidance sabbatical.

This involves getting wholly away from the suspect environment for a discrete period of time (preferably two weeks or more).

While people may or may not feel better during the sabbatical, it will allow them to be much more likely to be able to tell whether the building is having an effect on them upon their return.

(Note that those who are healthy likely will not be able to use this test, since their bodies may not react strongly to the mold even after an extended exposure away from it.)

A challenge with the mold avoidance sabbatical is that it is similar to doing a trial away from gluten – even a very small amount of continued exposure to the problematic substance can prevent the experiment from being a success.

Unfortunately, many people who have been made ill by a moldy home have found that it’s not enough to just get away from the building.

Possessions that have been in the home can hold enough contamination to keep sensitized people totally sick, all by themselves.

Therefore, leaving behind all possessions for the duration of the sabbatical can be important.

Considering building mold and the locations effect when choosing where to do the sabbatical can be important as well.

The mold avoidance sabbatical is discussed at length in the book A Beginner’s Guide to Mold Avoidance, which is featured on the Mold Avoidance page of the Paradigm Change website.


More Information

Much more detailed information about the topic of mold testing is in the Paradigm Change blog post called “Dr. Oz Tackles the Topic of ‘Mold Poisoning’: How’d He Do With It?”

The book A Beginner’s Guide to Mold Avoidance also has more information about determining whether a home is safe for occupancy by mold-sensitized people.

Dr. Ritchie Shoemaker’s website, Surviving Mold, offers information on the ERMI and HERTSMI-2 tests.

Greg Muske shared information on mold testing and on the ERMI in the remediation section of his blog, Biotoxin Journey.

Michael Pinto of Mold Sensitized gives his opinions about mold testing in a blog post called “What’s the Best Sampling Strategy for My Mold Remediation Project?”

The website of the late toxicologist Dr. Jack Thrasher provides technical information about mold testing.

The website momsAWARE features an interview with Dr. Thrasher about the ERMI as well as a good explanation of how to interpret the ERMI test results.

The website My Chemical-Free House discusses mold testing as well.

-Summary by Lisa Petrison


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