Wondering if toxic mold is an issue in your home? Hiring a hygienist is one option. Another is to perform your own dust sample. Learn how to test for toxic mold.
Dust sampling can be a good way to assess the health of your environment. The ERMI (Environmental Relative Moldiness Index) test is recommended as a place to begin. Several labs offer this analysis, including EMLab P&K, EMSL Analytical, EnviroBiomics, and Mycometrics.
In a 2013 study, the EPA found the ERMI test to be “useful in comparing the relative mold contamination in schools.”
While ERMI testing does not provide all the answers, it can be an excellent first step when evaluating the health of an indoor environment.
momsAWARE offers Mycometrics’ ERMI and HERTSMI dust sampling kits, using a Swiffer-type cloth, through their Online Store. The cost of the ERMI is $290 plus return shipping, while the HERTSMI is $155 plus return shipping.
How to Test for Toxic Mold
Below is an interview regarding dust sampling with toxicologist Dr. Jack Thrasher, a leader in the field of indoor air quality.
What is the best way for an individual to test a building for toxic mold?
Take note of visual observations and photos of the water damage and mold growth. (Remember, 50 percent of the mold is hidden, thus visual observations are simply a starting point.)
Use a moisture meter with penetrating electrodes to test wall cavities, ceiling, and all other areas of the home. Draw samples from wall cavities that have elevated water content. (Samples will typically be drawn by a hygienist, who will drill small holes and insert a tube to draw an air sample.)
Why is a dust sample preferable to an air sample when testing your home for mold?
Air sampling is unreliable because the results are too variable. Air sampling only identifies mold spores to the genus level. It is important to know the species of mold. Mold spores are present in the dust, and the dust can be examined for species of mold using PCR (ERMI) testing. For example, we tested a building in Bermuda. Initial air samples indicated low concentrations of mold spores. We then disturbed the indoor air with an aerosol of sterile fluoroethane. The spore counts went up as high as 250,000 spores per cubic meter. Thus the spores entrained in dust were redistributed into the indoor air.
Do you recommend the ERMI test as a place to begin when testing for toxic mold?
Yes. The moldiness index is not too meaningful, particularly for sensitive and high-risk people. The portion of the ERMI test that is important is the identification of mold species. Often dangerous molds such as Aspergillus versicolor, fumigatus, and flavus along with certain species of Penicillium are present. These species cannot be determined by spore counts because Aspergillus and Penicillium species have almost identical spore structures. Also, Stachybotrys does not readily shed spores, but can be found in dust and bulk samples by PCR analysis.
When vacuuming (or using a Swiffer-type cloth) for an ERMI test, is it best to draw dust from one spot, or take from a variety of places around the home?
I personally recommend doing dust samples from various areas of the house. Excellent sample areas are refrigerator coils and other hidden dust accumulation areas (e.g. under washing machines), giving the history of the home since installation of the appliances. Dust from the top of drop-down kitchen cabinets is another source. One can also use carpet dust, although this may not tell the whole story. In conclusion, collect dust from areas in the house that do not readily get cleaned. Keep all dust samples separate from each other—if the dust samples are mixed, one does not know which areas are most contaminated. However, if there is no concern for identifying the areas involved, one can mix the dust samples. I also recommend taking bulk samples of mold growth and subjecting them to an ERMI test.
One may also use a sterile wound-covering gauze to wipe the valleys of the HVAC ducts and gather dust as noted above. Wear sterile rubber gloves and put in a Ziploc bag. Same with the refrigerator. Always do ERMI-36 and mycotoxin testing.
(Dr. Thrasher recommends mycotoxin dust sampling and urine sampling. Both are available through RealTime Labs.)
Is it best to keep the house closed up for a day or two before taking an ERMI sample?
This is not a necessary requirement. The reason is that certain molds are associated with different substrates. For example, Stachybotrys requires a cellulose source, such as drywall, while other species of mold will be associated with flooring and carpeting.
Do I need to sample areas that I don’t suspect have been affected by the mold?
If mold is indoors and in wall cavities, all areas of the home are probably affected. Therefore do the dust sampling as discussed above. Some areas may have fewer spores than others; however, the mold spores will drift throughout the house.
What about bacteria?
Both Gram-negative and -positive bacteria are also found indoors. The Gram-negative are producers of endotoxins. The Gram-positive release toxins. The Gram-positive bacteria are Staphylococcus, Streptococcus, and various species of Bacillus that can be pathogenic. Also, the Gram-positive bacteria include the Actinobacteria, including species of Streptomyces, nontuberculin Mycobacterium, and Nocardia, to name a few. The Actinobacteria are potential pathogens and release toxins into the indoor environment that are more toxic than the mycotoxins produced by molds.
What is involved with taking bulk samples?
Bulk samples are just what the word means. One cuts out a piece of the contaminated materials, e.g. drywall, carpeting, etc. Put it in a Ziploc bag, date and label the bag, and send it to the testing lab. If litigation is involved, then a chain of custody is needed and a witness to the sampling.
If I see visible mold but have no ill health effects, should I still test my home in this way?
Yes. How does one know that they do not have ill health effects? The health effects can range from just sneezing through systemic conditions of not feeling well.
What else is important to emphasize about testing for toxic mold?
Too much emphasis is being put on molds. It’s important to remember that the indoor environment is a complex mixture of biocontaminants (mold, bacteria, and their by-products).
For more information on Dr. Thrasher’s work, visit his website. Read more about the role of other contaminants in the paper The Biocontaminants and Complexity of Damp Indoor Spaces: More Than What Meets the Eyes.
Would you like to know more about toxic mold? See A Beginner’s Guide to Toxic Mold.
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I’m planning to do an ERMI test in our house, but if the test comes back positive for toxin-producing mold, how will I know what/where to remediate? We do not have any obvious areas of mold or water intrusion, but I know that I am mold-susceptible, and my lab results are getting worse.
Stephanie,
Doing an ERMI is the next step. You cannot predict the next one really until you take this one. If you find some toxic molds you can do some thermal imaging to find places of hidden moisture. You are wise to do this. I would be happy to look at the results with you.
You are wise to be thinking along these lines.
Andrea,
That makes sense. Thanks for the offer of help interpreting the results. I find those rather confusing.
Hi, Andrea. Thank you for all this information. We’ve been sticking our heads in the sand for too long in regards to the mold problem in our house and the toll it is taking health-wise. I want to order the EMRI asap. I have a question about how to do the test, though. According to what I have read (if I understand correctly), the testing companies seem to recommend taking samples from two areas of the house – the living room, such as the sofa, and one bedroom. There is a certain square footage that needs to be measured and then vacuumed. This post seems to imply taking samples from even more areas, which makes sense, of course. Do I need to order additional kits for each area I am testing, or just vacuum from more areas of the house and combine them in the collection container. If it is the latter, how do I know I am vacuuming a large enough area? Thank you so much for your help. I’m feeling overwhelmed by this whole ordeal. I was also wondering about vacating the house and all possessions. Are there any items that would be safe to take out? I am thinking specifically of my 14 y.o. son’s camera and equipment that he purchased in the fall. He worked so hard for it, and it means so much to him. SInce it isn’t porous, is there a way to clean it? Thanks again.
Meredith,
You are wise to be asking these questions. As far as the dust sample – it depends on a few things. Is there a place in the home that has known water damage? I would do a dust sample near this leak. You want to pick the best dust which often is in refrigerator coils, air vents, behind furnaces, etc. I know that the companies say to vacuum carpeting, but Dr. Jack Thrasher continually suggests “settled” dust. It will tell you more what you are breathing. If you want to get a picture of what’s in the house, generally then collecting dust from various parts of the home will work fine. If you want to know what each room has in the way of mold then several test kits can be a good idea. If your overall sense is that I just want to have an idea of what we’re breathing – then one test kit will help you find out. As far as his camera – I would wait to see what the dust shows. If no stachybotrys is involved, it’s possible to clean this. My husband’s radio equipment was successfully cleaned once we knew his office didn’t contain the stachybtorys. Once you test, I’d be happy to look over the results with you.
Thank you so much for your reply, Andrea! And your offer to look over the results. I ordered the test and am awaiting its arrival. Thank you for the clarification on how to get samples. The problem with our home is one of general dampness due to being built on an underground seasonal stream and being in the woods, it never properly dries out. The walls, floors, and the contents of our house get moldy, especially in the summer. We had the crawl space remediated and “waterproofed” several years ago, but it didn’t solve the problem.. There is just too much dampness and water. For this reason, I am afraid that remediation will be impossible. Do you have any thoughts about this? The reason we have ignored it until now is that the home is VERY underwater – mortgage-wise, that is, due to the financial downturn, which was especially bad in our area. We can’t sell the home, and knowing about a mold problem will make that even more impossible. Sooo… if we have to leave, it will be a huge financial/credit setback. Of course, all that means nothing if we don’t have our health. Thanks again to you!!! I look forward to sharing our ERMI results with you when I get them. Best wishes!
I think you’re right, nothing matters except your health. You can’t lose to make that the priority. It does sound like this will be tough to remediate. Keep me posted. Meredith.
Hi Andrea,
Thank you for all of this wonderful information. I have seen the recommendation of using Mycometrics as a lab for ERMI testing from various blogs, etc when it comes to testing for mold. When I go to the site, it looks very outdated and primitive with the most recent article posts from 2007. I called the lab twice yesterday during its business hours and the phone rang many times and finally went to voicemail. I did leave a voicemail and I have not yet heard back. Am I in the right place? http://mycometrics.com/ Also, I noticed that the site didn’t have any FAQ regarding the tests available. Do you by chance have the answers to any of the following questions? I’m trying to remain hopeful, but I’ve noticed a lot of strange sites with a lack of information, spelling errors and an eerie vagueness about the services offered when it comes to investigating mold in the house and/or treating humans; which leaves me wondering if people are taking advantage of really sick and desperate people. I hope this is not the case. Have you or anyone else out there experienced this feeling on your search to getting better?
How many people work at this lab? What are their credentials?
What are the limitations of this testing?
How will the ERMI/HERMSI testing help me in my own journey of recovering my health and understanding the health of my home?
Please explain the difference between the ERMI and the HERMSI.
How many different samples can I submit from my home?
How long will it take to get results?
Please explain the mechanism of PCR testing?
Thank you! Your blog is wonderful. It is organized, easy to read and visually appealing. It has been a savior on this mold journey. It is so incredibly nice to know that there is a community out there of people taking their lives back and working to educate and support one another!
They have a very small staff with a credible lab. I have spoken with the founder and owner and found him to be amicable and knowledgeable. I can’t answer all of these questions, but here are a few:
Any test is limited. Air sampling, bulk sampling, tape samples, dust samples all have limitations. But if you test the dust from settled dust like behind a refrigerator you can get a good idea of the kind of contaminants in the home.
ERMI tests for 36 types of mold and the HERTSMI only five….Mycometrics will offer a consultation with the ERMI but not the HERTSMI. I have found either one to be helpful depending on the situation.
It generally takes approx. five business days for a result.
You can take as many samples as you like. If you have an idea of the source, you can take the dust from near the source.
It’s important to rule out the presence of high levels of toxic molds in order to avoid fighting an uphill battle when it comes to recovering your health. I am not knowledgeable about PCR testing, only the genetic testing for mold vulnerability. I hope this helps.
Hi Andrea!
Can I cut the sheet they sent me to take various dust samples, or is that not recommended? Or, can I use another swifter sheet to collect more? I wasn’t sure if that sheet is sterile, or if I collect samples ( such as from inside air ducts that have caked dirt) if I can then use my own ziploc bags? I want to get the best information as possible. t
Would it confuse the labs results to collect dust from various areas and put them all onto one sheet? I essentially want to just get the facts on what kind of mold we have. The test said to ‘not’ collect directly from mold you see visibly for some reason. We have mold growing around the circumference of the HVAC supply pallum and really need to know what kind it is, because it appears to have eaten though.
Thanks a bunch! –Natalie
You can’t cut it. You’re fine to take a bunch of dust from all over the house. You can take it near the pallium or from everywhere. Either way you’ll get to see what you’re breathing. I’d be happy to look over the results with you!
I think there may be mold in the walls under poorly sealed windows and in the kitchen floor beneath the loose linoleum tiles. Should I have sampled inside the wall like inside an electrical outlet hole or gotten a sample under the loose flooring?
No, you want settled dust in any areas of the home. The dust often tells the story without opening up walls. I’m happy to look over any test results with you, Anna.
I have 3 ceilings with leaks/water damage. My home is 100 years old; 2 stories, a cellar and crawl space, and partial basement. Would I begin with the ERMI or an industrial hygienist in your opinion? It seems I would get more bang for my buck with the hygienist, as they retest after remediation, which is included in the price, about $1500. The ERMI would cost about $1200 to test all 4 spaces just the one time. My mom is living with me, as we had to remove her from her home. I ERMI tested her place, and it was unsafe for her to be there. She begins a detox next week, so am anxious to get moving on this. Thank you so much for any advice! Her doctor recommended your book, which I am purchasing today.
If you have this much water damage and the home is this old, you can assume any health issues are related. No need to test all spaces. This is primarily about your gut instincts on whether this home is a safe home for you. Our homes are complex structures and tied together via air ducts so no need to “overtest” to determine a course of action. Good job making this connection.