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, and Mycometrics.
Below is an interview regarding dust sampling with toxicologist Dr. Jack Thrasher, a leader in the field of indoor air quality.
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 did 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?
I always recommend the ERMI tests. 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 for an ERMI test, is it best to vacuum in one spot, or take from a variety of places around the home?
What one must understand is that a single dust sample does not necessarily represent the contamination. I prefer doing a minimum of two samples. The more the better. The species of mold in a contaminated home will vary from room to room. Carpeting can be done - but from one room only, which is usually the most contaminated room. "Historical" dust samples should be included in the testing. Sites for these include the refrigerator coil dust which is a 24/7 collection site, as well as any drop down kitchen cabinets, or return air for heating and air conditioning. If the home has a basement, it should be assessed as well.
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 others species of mold will be associated with flooring and carpeting.
Do I need to vacuum 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. In addition, the Gram-positive bacteria includes 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.
How does one test for bacteria in the home?
Bacteria are tested in buildings and homes the same way. One can use bulk samples (see above) or sterile Q-tips. Take samples of suspected contamination. Culture using sheep blood agar (SBA) and TSA (Trypticase soy agar) at both 35 and 50 degrees centigrade. Have the laboratory identify the bacteria to genus and species. Also, ask them to culture for Actinobacteria. The Actinobacteria bacteria are slow growing and require several days to identify.
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 is important to emphasize about testing for toxic mold?
Too much emphasis is being put on molds. 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.
About Andrea Fabry
I am a former journalist and the mother of nine children ranging in age from 28 to 12. My husband Chris, myself, and our children find ourselves in the desert of Arizona attempting to rebuild our health and our lives following a massive toxic mold exposure. The organization momsAWARE comes out of this crisis as a means to help educate and empower others on the subject of environmental health. Our family has also launched a natural line of personal care products called Just So, available at our Online Store.
Just So Natural Products
Our Work Together
Thanks for Stopping By!
Visitor Count:
Number of Visitors:
Hi Andrea,
ReplyDeleteThank you so much for the wonderful info throughout your blog. We did a ERMI test based on previous ERMI posts you had made. We had very scary results (stachyb, etc.) which we later realized was a "sampling error" and thought I'd pass along some of the lessons we learned.
(We're in the process of trying to schedule an appt w/a mold remediation co).
The source of problem is related to leaky windows causing water to accumulate behind the wall cavity under the windows. The screens were blocking the exterior drain so rainwater would accumulate. That, combined with some of the screws not properly tightened caused water to accumulate in the wall cavity under the windows.
Around the same time this was happening, I came across the post you made about the horrific story that one of your readers had submitted and agreed to share re: leaky windows...I do hope that family is doing better. My health issues are too complex and to lengthy to include here, but yes, mold is involved (one clue: I'm allergic to plant-based digestive enzymes made from aspergillus mold). But sadly, mold is not the only issue in my case...long story).
Anyway, re: the windows - when the insurance adjustor visited our home, he requested that we open up all the windows to investigate the problem and determine cause, etc.
Unfortunately, there were 2 rooms with windows within close proximity to a some bushes (the hedge variety, don't recall the name) where mold accumulates. The 2 rooms tested positive for stachyb. We were devasted beyond words as you can relate. One of those rooms was the playroom of our 5 year old daughter.
The strange thing was that the other room with stachyb. was our dining room, which is next to the KT, but our KT did NOT test positive for stachyb (and there's no door that closes off the kitchen from the DR). I was puzzled by this b/c I thought if there's stachby in the DR, why didn't it show up in the KT too? (and we discovered water on our KT tile floor, originating from the behind the baseboard).
We then realized that my husband vaccummed the window sills (interior) to get the ERMI sample AFTER the adjustor visited our home and asked us to open up all the windows; this increased the chances that mold from the bushes affected the test results.
We decided to re-test and this time, we vaccumed the floor in areas that had NOT been previously sampled and the test came back with NO stachyb, and significantly less of the other types (Aspegillus, etc.....)
Lesson learned:
1. Do not open windows in areas where bushes are in close proximity before the ERMI test (or better yet, not at all, as long as the bushes are still there).
2. Use a moisture meter 1-2 times after a rainfall to check for moisture behind the walls that are located underneath windows (e.g. a good time would be around the time we set our clocks back, change smoke detector batteries, etc...but most important is AFTER a good rainfall). (Virtually all of our windows tested high for moisture).
3. After a good rain, check the drain of the windows (outside) to make sure water isn't accumulating on the window railing from blocked window drains.
4. When in doubt (e.g., borderline to high moisture reading), remove baseboard to check for signs of mold BEHIND baseboard. This is the best way to confirm because there's no paint behind a baseboard (for those who don't know, some paints can prevent mold or water damage from showing through the paint).
5. If insurance adjustors require windows to be opened, take precautions to reduce the chances of exterior mold that collecting on the outside railing of the window or on bushes near windows from flying into the house.
Hope this helps.
Thanks again for all your efforts in sharing such important life-changing information.
God bless you.
Cary
P.S. BTW, have you found any digestive enzymes that work for your family?
Cary,
ReplyDeleteThanks for the information. These are complicated issues which raise complicated questions.
As for enzymes....I try to give them in the form of sauerkraut and other fermented foods. Lacto-fermented foods are loaded with good, healthy enzymes.
I often see people on the GAPS (Gut and Psychology Syndrome) forum recommend Dr. Houston's enzymes...here is a link with some of these:
http://www.spectrumsupplements.com/content.asp?node=333&cateid=10
Thanks for the guidance in this process. I have had my home remediated for high spore count, but no visible mold in the crawl space. I recently had a french drain installed inside to allievate the water problems that rise up from under the foundation. during extremely heavy rainfalls. Air quality tests show the house is safe. But how can I be sure????
ReplyDeleteIt's always a good idea to run a dust sample in addition to an air sample. If you can take the dust from a spot with settled dust and it comes back clean...you can have a bit more peace of mind.
ReplyDeleteThanks for such an informative blog. I am just beginning the journey, having recently discovered the reason for my health problems (mold) and finding mold in 6 places in our house! (so far)
ReplyDeleteMy question is this. If I have recently had mold mitigation in various places in the house, will the dust that would have been there since before we had this done, such as behind the refrigerator, show a false positive reading? I want to do the ERMI test, but am not sure if I should somehow try to clean ALL the dust out first and start fresh, or just go ahead and do it.
To further complicate matters, we had a kitchen flood (with LOTS of mold) which as resulted in the need for a complete kitchen remodel, which will begin in about a month. Should I wait until after that is complete, or test first? I want to avoid having to cut into our brand new kitchen later on. It is all so overwhelming.
Amy,
ReplyDeleteI would do an ERMI test now. Any remediation company should advise testing before remediating. It's critical to have a "before" and "after".
Since you don't have this for your other areas, I suggest doing an ERMI in another part of the house in settled dust. It's important to see what you're breathing now.
You are on the right road with this. I'd be happy to speak with you further...my direct email is andrea@momsaware.org
A relative lives in a condo which had a water leak in one unit that also leaked into the hallway carpet. The people living on that floor what testing done since there is still a slight odor after clean up. The association says all is well, no mold and no problem but will have someone do the ERMI test. How can we be certain that they will do it correctly. If they don't want to find a mold problem can they vacuum so they won't find any?! What can we be watching for to make sure they are doing it the right way?! Thanks very much!!!
ReplyDeleteI would ask to be present when they do the test. Bring these directions and be sure they find some settled dust. Or you can request that you do the test. Either way, you are right to be cautious and concerned about the testing process!
ReplyDeleteAndrea, which directions do we bring? They are using a vacuum container from assuredbio but how can we be certain that they will collect dust from the right place. Is there anyway they can collect "good dust".Where should we be watching that they take the samples from? We probably will also do one on our own to have a second opinion. Must the container be filler with dust. I would think that dust from the carpet would be more than from a bookcase, chair or door frames. Should we vacuum from under a couch, table, chair that doesn't get lots of traffic or a high traffic area? Thank you! All very confusing to us.
ReplyDeleteDoing your own makes sense. You would want the settled dust..under furniture. I'm not sure about the amount of dust in the container. I'm sure Dr. Thrasher would be happy to answer this question:
ReplyDeletetoxicologist1@msn.com
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.
ReplyDeleteStephanie,
ReplyDeleteDoing 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,
ReplyDeleteThat makes sense. Thanks for the offer of help interpreting the results. I find those rather confusing.
Andrea,
ReplyDeleteWhere can I obtain a thermal testing unit or a company that does this type of work? I live in the Puget Sound area-needless to say very moist, dark and moldy-and trying to get well!
Thanks, NancyL.
Try a home inspection company. Or a hygienist. One other thought is a mold remediation company. They will charge in the range of 100 dollars to check for hidden moisture.
ReplyDelete