A Lymie Goes House Shopping: A BASIC Guide to Mold Testing

Nothing is ever simple with Lyme, is it?! I am in the market to purchase a home, and it turns out, even this is impacted by Lyme. You see, I’ve come to learn that getting well from Lyme is nearly impossible if the patient is living or working in moldy environments. There are types of mold, you see, that release myotoxins into the air that actually suppress your immune system. Obviously this is bad for everyone, but it’s especially bad for those of us fighting infection.

To my knowledge, mold has not been a part of my Lyme illness to date. And I am by no means a mold expert. But I knew enough to be cautious about moving anywhere that would make it more difficult for me to get well, so I brushed up on some basics of mold testing. I thought I’d share what I’ve been doing to measure safety of prospective homes.


Testing for mold is simpler than I thought. I am loving the dust tests from Mycometrics. You have two options:

  • The ERMI test is the most comprehensive option, and profiles molds of all types. This test was designed to be used when you’re analyzing a building for the first time.
  • The HERTSMI test looks only for certain types of mold MOST associated with water damage (NOTE: does not include humidity grown molds). This test was designed to be used to assess the completeness of a remediation project and should not be used when profiling a house for the first time.

UPDATE: Don’t make the same mistake I made. When I was house shopping, I began to run HERTSMIs to save money. My HERTSMI on a new construction home was very good, with a score of 4. I bought it feeling safe. But within 2.5 weeks of living there, I discovered the entire attic to be full of mold. I lost that home, all the money I put into it and literally all my belongings. I was homeless for 2 months and will have bad credit for 7 years. It was a $40,000 mistake I made trying to save a couple hundred bucks.



You can, of course, order the tests from Mycometrics. Or you could save yourself $50 by putting together your own kit. All you need is:

Once you have all the supplies, put on a pair of the latex gloves, and open both your boxes of Swiffer sheets and ziplock bags. Being careful not to contaminate your Swiffer cloth by letting it touch any surfaces, place one Swiffer cloth into one ziplock. I knew I’d be testing multiple homes, so I made 5 or 6 kits to start. Print off one chain of custody form and one credit card payment form to go with each bagged kit. You’re ready to head to your property!


When you reach your property, get ready to play detective. First step, is to put on a fresh pair of latex gloves. Then, remove your Swiffer cloth from its baggie and search for dust. I like to take a little from each room of the property. You’re looking for OLD dust if you can find it. Trust me, it’s there. Run the cloth along tops of door jams, tops of picture frames, on top of water heaters, inside cabinets, behind the fridge, behind the stove… anywhere you can find it. Each time you take a good swipe of dust, move to a different section of the cloth. Once you’ve collected a good bunch of samples from each room, return the Swiffer cloth to the ziplock, press out the air and seal.

For each baggie, use a sharpie to write the following information directly on the bag:

  • Address of location sample was taken
  • Your name
  • Your phone number
  • Your email address

When you get home, fill out your chain of custody form and credit card payment forms and you’re all set!

Logistics: If you’re purchasing a home, timing is everything. I like to collect my dust sample as early as possible. Most agents were fine with me collecting dust during open houses. I’d simply say “Wow, this is a beautiful home, I’m very seriously considering an offer. I do have a mold sensitivity, do you mind if I collect a little dust to sample?” EASY!

It’s $44 to overnight the completed kit to Mycometrics. If it arrives by 10:30am ET, they can do a same day turnaround. 3-day and 2-day options are also available. Standard is 5-7 business days. So long as you get results within your inspection contingency window, you’re all good. I even had a property where I  mold testing before making an offer.


Depending on how fast you asked to receive results, you should receive an email from Mycometrics within a few days. Take a deep breath, it’s time to interpret your results. It’s good to know ahead of time that all dwellings contain mold, so presence of mold is NOT a deal breaker. What you’re looking for is how MUCH mold is there, and what strains are highest?

The ERMI test comes in a nice little report that will give you an overall score on the relative moldiness of your tested area. Scroll down to the bottom of your PDF, and look for the row labeled “ERMI (Group I – Group II)”. This is the magic number – it’s on a scale of -10 to 20. Dr. Shoemaker of SurvingMold.com encourages Lymies to live in places with a score below 2.0. Additionally, you should look to be sure your molds in group 1, and group 2, when combined is a score of less than 30.

Whether I got the ERMI or the HERTSMI test, I also like to do the HERTSMI scoring, which assesses the relative risk associated with the dangerous strains of mold that are present in your sample. Here’s how to do it: On your ERMI PDF, locate each of the lines associated with a particularly dangerous strain of mold. If you did the HERTSMI test, this is easy, as those are the only ones listed. Next to the name of each strain, look to see how many spores were found, and give yourself a certain number of points for each of the following:


According to Dr. Shoemaker, who developed this scoring model, your overall score falls into these categories:

<11      Statistically safe for re-entry for those with CIRS (chronic inflammatory response syndrome)
11-15   Borderline; clean first and re-test before re-entry
>15      Dangerous for those with CIRS. Do not enter.

Even though I don’t have CIRS, I was aiming for a HERTSMI score of less than 11. I figure, if it’s safe for CIRS folks, it’s safe for Lymies. But use your judgement here and talk to your doctor!


Deciding what to do with your results, is of course the hard part. Like anything Lyme related, it’s complex and ultimately a very personal decision.

The first place I went into had a low HERTSMI score, but a high ERMI (over 4.0). So it was overly moldy, but not especially dangerous. I thought about buying it anyway, but I had a Lyme friend who is mold sensitive peek her head in and she reacted… that was enough reason for me to back out.

The second place I tested was very high ERMI and very high HERSMI, especially in Stachybotrys chartarum which is the dreaded toxic black mold. I read later in the HOA meeting notes that the whole floor had flooded so badly some of the units had to be rebuilt… a fact that was left out of the disclosure document. Thank GOODNESS I tested!

The third property I tested was a more modern building (the previous two had been vintage) and it has almost no detectable mold. DREAM COME TRUE. Only I didn’t win the bid, darn it.

I’m currently mold testing on my 4th property. Fingers crossed! But overall, I feel like these tools are helping me make better decisions about where to live next, ensuring it’ll be a good move for my wellness.

I hope the info helps you in your own testing! Best of luck out there!


9 thoughts on “A Lymie Goes House Shopping: A BASIC Guide to Mold Testing

  1. So do you have to send each baggie separately at $44 apiece let say I want to just do my bedroom and bathroom and one bag and the rest of my house in another bag would I send those separately


    • If you want to tell WHERE the mold is, yeah that’d be the way to do it. Not sure where $44 a piece comes from… I think each sample is charged full test price separately. Hope that helps!


  2. Mycometrics changed the rules and does not give the discount for using your own swiffer — everybody has to pay the larger amount. Still better than having to do the full ERMI! Any idea what HERTSMI stands for? I was searching for that when I came across your site. I know ERMI is Environmental Relative Moldiness Index – but never knew what HERTSMI stands for!


    • Interesting, I’m not sure I understand. I never got a discount for using my own, but I saved money by not having to purchase a kit. I think that’s still the case. As for HERTSMI, I’m not sure what it stands for! But I will never run those again when initially testing a building. I will always run an ERMI. Not sure if you read my most recent blogs, but I ran a HERTSMI on the home I just bought and I have discovered a huuuuuuuuuuge mold problem that has left me homeless and without access to any of my now contaminated belongings. So I say run an ERMI. 🙂


  3. So you lost a home that was moldy but not from the top toxic molds that the Hertsmi would show? I opted to do the Realtime Labs Emma test that covers the top toxic mycotoxins and molds. I should be receiving the results back soon. I am sort of mold sensitive and have lyme but my lab results were high on the tgf beta test and my doctor told me to test my own that we built and have owned for 17 years now. I don’t know where the mold is but am so terrified it’s going to be the molds that we do have to lose everything with. Could non-toxic molds on the ERMI be causing my CIRS too?


    • You’re correct. The molds that are supposedly non toxigenic can also be problematic for Lyme and CIRS. This is why I’ll only ever run ERMIs from now on.

      I made it into remission this summer and was doing well. Then I visited a home several times and relapsed. Tested that home and – once again – it was high in non toxigenic molds. (Cladosporium and epicocum, specifically.)

      Experts have only identified some types of Mycotoxins. It’s likely these molds are creating problems not yet identified.


  4. Does Mycometrics still currently accept your own home-made kit (swiffer and ziplock baggy) for the ERMI test? We are house-shopping and plan to do this. We’ll have a 12-day window to get it done. Do you think that will be enough time? How did your house hunt go? Did you finally find the low/no-mold home of your dreams? 🙂


    • Yup! I did it just a couple months ago and they accepted homemade kit no problem. 🙂 12 days is plenty. You will want to overnight via fedex and get a rush on the processing at mycometrics. It gets expensive. I think I was dropping $400 a house. I tried to save money at one point by running just the HERTSMI. Really wrecked me. I bought a house that ended up having mold and had to walk away. A year and a half later I’m about to foreclose on it. Only lived there 2 weeks. Lost everything I own. Heh. But. I am ok. And I’m very healthy now. 🙂


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