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  NOTE: May Dooley passed away in March 2024. This site will remain available as a tribute to her.

Tape Testing Instructions for Locating Sources of Mold Growth

NOTE: The newest testing instructions (from March 2022) are available here as a PDF file.
Mailing instructions for sending me tape samples are on the Contact page.


Mold needs food and water to grow.
Where would it find both at your home?

For food, consider mold's job in nature: to break down organic material, such as wood and natural fibers. It is less likely, but not impossible, that mold will grow on synthetics, on paint (which usually contains a mildewcide), or on concrete.

For water, think about the basement/crawlspace with higher humidity and about water pipes and leaks and floods. Think about where rain might penetrate the home.

Sometimes the most obvious (visible mold) is a minor player. Most mold is invisible. Mold in wall or ceiling cavities wouldn’t show up in air samples – but the gases emitted through continued growth could affect health. We need to be mold detectives…and sometimes mold dogs!


Use transparent tape, such as that sold by Scotch. There are links to the tape being sold at Amazon on the Contact page.

To send the tape to me, place it on the outside of a zip-lock bag. Part of the tape strip should extend off the end of the bag to serve as a tab. Number the strips by writing on the tab (do not write on the plastic bag). On a separate piece of paper, indicate the location where each numbered sample/strip came from.




  1. If you are not sampling obvious mold, touch each tape strip to a few spots in the same vicinity of what you are testing. Get some visible debris on the tape but not too much. The light from the microscope has to be able to go through the debris. When sampling shelving in a basement, touch the tape to the undersides of the shelving, not the dusty top.

  2. Sometimes it can be useful to ask the question, "Well, why wouldn’t mold be growing here or there?"

  3. It is important to find where mold isn’t, as well as where it is. You see a discolored area on a ceiling joist in the basement. Is that a spot clean-up or remediation of the whole basement? Check "control" areas that look clean as well as discolored areas. High levels of mold may be present but not visible to the naked eye.


Stick one end of a 3 inch piece to your thumb and the other to your index finger, sticky side out. Press just the center of the tape to the surface. Leave the ends sticky. Only 3 inches will fit on a small microscope slide, so save on your tape, and just send me a 3 inch strip. Extra gets discarded.


1. Is the structure of the basement or crawlspace moldy?

Do a couple tape samples on the ceiling joists and sub-flooring in different sections of the basement. Sample on the underside of the bottom step.

Old wood is generally more mold resistant than new wood. Old wood is usually denser, better quality, dried out, and has less nutrient value than softer new wood. At one conference, the presenter called new houses "self-composting houses." In a newer basement especially, consider painting every square inch of wood to protect it from most mold.

2. Are contents in the basement moldy?

Check vulnerable surfaces (do composite samples, where one tape is used on several spots each of multiple pieces), such as unpainted wood shelves, books, furniture, straw baskets. Don’t store vulnerable items in the basement unless in plastic bins. Don’t "feed lunch to mold"!

If you have any pressed wood shelves, sample them separately. Older shelves may have high levels of Aspergillus mold.

Is there mold behind finished basement walls?

Does the basement smell moldy if the dehumidifier is turned off? If so, there is mold growth somewhere. Finishing a basement raises the risk for hidden mold. Foundations are not waterproof, and then we add sheetrock with paper backing. Now mold has food and water (even if the water is vapor).

By the way, when dehumidifiers are run in moldy spaces, they can get moldy, too. The filters protecting the innards are not very effective.

If there is thick insulation in the wall cavities, it may protect the back of the sheetrock from mold. Likewise, insulation between ceiling joists may mostly protect surfaces it covers, assuming it is not put on backwards. The vapor barrier should face the "warm," that is, the living area of the house.

How would you check for mold behind finished basement walls when you can't drill a hole and do an air sample in the cavity? There are less intrusive options:

Slide a putty knife with tape over it under base molding on each below-grade exterior wall, several spots.

Try to snake your hand down to the bottom of the back side of the drywall and sill plate (horizontal wood on floor - the part of framing that drywall is affixed to) - either through an access hole if there is one – or maybe from an unfinished adjacent area.

Extrapolate from another area. If you find mold on other accessible sill plates (such as under steps) or mold on ceiling joists/sub-flooring, the chances could be that maybe this basement shouldn't have been finished.

If you see a lot of efflorescence (mineral deposits) on lower foundation walls in unfinished areas, maybe there is water infiltration from lower foundation walls in finished areas, too.

Walk around your outside foundation during a heavy rain. Are downspouts directing water away from the foundation? Is water ponding by the foundation wall?

What kind of soil do you have? Sandy soil allows for drainage much, much better than clay soil. I inspected two 100 year-old houses, side-by-side, on Long Island. The unfinished basement at one house was fine, no mold. The next-door finished basement had mold on the new materials. Lunch was fed to mold.

3. Did a toilet overflow get into the wall cavity?

(There might also have been a leak before you owned the house. Aspergillus and Penicillium can grow indefinitely in wall cavities.)

Wrap 3 inches of tape around the end of a putty knife (or credit card, dinner knife) and slide it under the base molding in a few spots behind the toilet … or, to check leaks at shower fixtures, under base mold on the other side of the common wall with shower fixtures. Finding mold here raises the risk for hidden mold in the wall cavity.

You could also use this putty knife method for sampling under base molding under a window, next to a shower, in a finished basement on an exterior wall, between floor cracks, and so on.

4. Is there mold in the sink cabinets?

Touch one tape in the rear around the plumbing, including at the joint where the back meets the bottom and inside plumbing access holes, as best you can. Wrap the tape around the end of your finger and try to poke your finger into the access hole.

If water got under the base of the cabinet or in the wall cavity behind, hidden mold would likely be a bigger issue than what you can pick up with tape. Remediation may be needed.

5. Is there mold on the living room furniture because furniture was once in a humid house?

Do a composite sample from the undersides of each piece of furniture and on upholstered surfaces. When I am at a house, I do a composite sample room-by-room to rule out mold on furniture. You could consider sampling furniture in a few of the main rooms that you spent time in. This would especially apply to vintage furniture or furniture from unknown sources.

6. Is that spot on an attic rafter mold?

Sample the spot but do a second sample in control areas. Again, it is as useful to know where mold isn't as where it is. There can be high levels of mold that are not visible to the naked eye. It might be useful to know if you have to clean up a spot or the whole area!

Attic mold, as long as not excessive, may not be a health issue if there is adequate ventilation. But discolored areas could be addressed prior to listing a house. There are various patterns of mold growth in an attic. Feel free to call to discuss. One of the most concerning would be white mold where rafters meet roof decking or just on roof decking in an attic without adequate ventilation and when shower exhaust fans terminate in the attic or when an insulation installer has inadvertently covered up soffit vents.

7. Is the dark discoloration on a shower curtain, bathroom ceiling, windowsill, or vent cover mold?

It’s just Cladosporium, which grows where there is condensation and can just be wiped off. This an allergenic mold for some, but not one of the worst. Usually it is not necessary to tape sample mold in these locations. In my experience, Cladosporium doesn’t get airborne from these areas, though, if air samples were done, Cladosporium would show up, because it is also the most common outdoor mold.

8. Is tape sampling good for testing rugs?

No, not unless the rug has gotten wet, and then there may be mold in/under it.

A better way to test rugs is a lab test with a vacuum sample. Buy a cone (about $12 as of October 2021) to fit over your vacuum cleaner nozzle from Assured Bio Labs and order their Big 2 test. The cone is manufactured so that it collects the dust from the carpet and lets the air pass by. When you get the test kit, vacuum a square yard of area. It is OK to break up the yard and do square feet here and there. Vacuum each square twice, from different directions (that is, top to bottom and then side-to-side). Note: They have a video of the test showing a cotton swab for collecting dust, but that is for room dust or dust from the underside of AC fins. The cone for carpets.

This DNA-level test counts microparticles, that is, broken up pieces of spores and branch-like structures of mold growth. Numbers will be higher than spore testing. We are primarily interested in Aspergillus/Penicillium water-damage molds. I can help you interpret lab results.

Another approach to gauging microbial life from water-damaged rugs is to do an endotoxin carpet test. Endotoxins are given off by bacteria and can affect health similar to mold. Check out the endotoxin carpet test at envirobiomics.com, for about $160 (price as of September 2021).

Rugs are not recommended on basement slabs, unless the basement was waterproofed during construction. Carpets in general are not a good investment in a house.

9. Should walls be tape-tested?

Generally, no. Paint typically contains a mildewcide, which discourages mold growth. Two exceptions would be dark discolorations on bathroom ceilings – usually Cladosporium due to condensation – and where there has been prolonged wetness – could be Stachybotrys, Chaetomium, Aspergillus, Penicillium, etc. Just wipe off Cladosporium. Prolonged wetness may call for remediation of the other molds.

10. Should I test shower grout?

Eh. Mold grows on shower grout. Clean it off. Make sure the shower grout is in good condition so that water can't penetrate below it. That's the more important issue. Follow the path of the water to find mold. Consider upgrading a conventional bathroom exhaust fan to something like a Panasonic Whisperquiet.

11. Is tape sampling good for testing the AC system?

No. The better test is the Big 2+ with Assured Bio Labs – see attachment. The Big 2+ detects tiny pieces of DNA and is much more sensitive than tape testing.

You call the lab for a swab and tell them that you plan to do the "Big 2 plus Chaetomium" test. You actually will be adding a few species to that, bringing the total from $65 to $85 (as of October 2021). For details, see the attachment, "Assured-Bio-Instructions." (This is the same test as done on a carpet, just different collection methods.)

Sometimes you will see black Cladosporium on a vent cover, due to condensation. This localized mold can just be wiped off. Double-check that the black mold is also not found deep inside the ductwork (by reaching in and sampling).

If you send me a copy of your Big 2 report, I will help you interpret it.

12. Follow the path of water/moisture to find the mold.

If water seeped under an exterior doorsill, there could be mold under the doorsill and by the adjacent posts. Poke a putty knife (or equivalent) with tape around it under the sill plate and posts. Someone with a good nose could also get on his hands and knees and sniff at the sill plate.

Submitting Tape Samples

Mailing instructions and my address are on the Contact page.

Enclose a check made out to EnviroHealth as follows:
 $15 – 1 tape
 $25 – 3 tapes
 $50 – 8 tapes
 $100 – 20 tapes

If you send more than 20 tapes, tapes over the 20 are $4/each. If you later send more tapes, they, too, would be $4/sample.

Example: 24 tapes would be $100 for the first 20 plus (4 x $4) = $116

Example: 10 tapes would be $50 for the first eight and then $5 each after that, until you get to $100, and then, $4 each.

Below is a photo of submitted tapes. There is a small ¼” inch tab on the left so that I can easily remove the tape from the plastic bag. (Put a piece of tape on a plastic bag and just try to get it off with your fingernail!)

Submitted tape samples

Some Questions and Answers

1. There was an ice dam, and I can see stains on the ceiling

If the drywall is accessible from the attic, investigate from there. Maybe dealing with mold from above could avoid a remediation job. But if staining is extensive and water went down into the wall cavity, remediation may be in order. Unless there is visible black mold on the ceiling (Stachybotrys), the mold, if any, would likely be confined to the attic side of the drywall.

If you plan to have a handyperson just cut out the stained area, first cover beds, rugs, etc., with plastic drop cloths. If there is not much staining, it could probably be painted over. If the attic above has ventilation, any gases produced by the mold would likely be dissipated in the attic, not drawn into the bedroom.

I'm guessing about half the time there are elevated levels of mold in a ceiling water stain when a drill hole is made and a tube inserted for air testing. Because a little bit of mold can make a lot of spores, it’s not possible, even from an air sample, to predict how much mold is hidden up there. How long was the ceiling wet? How much water? Where did the water travel?

2. The roof leaked

Follow the path of the water. If the leak was into a wall or ceiling cavity, remediation may be in order. Tape sampling probably wouldn't show anything, unless there was so much water that a tape from under base molding might be positive for mold.

4. A window leaked

You may get confirmation of mold by sliding a putting knife under base molding. Even if not, ask the question, "Well, why wouldn't mold be growing in the wall cavity?" You had wood, and now you have water. Bingo. Food and water. Plan on remediation or, if doing it yourself, protect furniture and rugs with drop cloths. Wear a mask. Maybe use a box knife to cut out drywall. Safely remove insulation and bag for disposal. HEPA vacuum in the wall cavity. Wipe any visible mold. Paint.

Unless there is a nearby neighboring house, you could also put an exhaust fan in a nearby window.

5. I just got my report for air sample results. Can you help me interpret them?

Look at the counts for Aspergillus/Penicillium. Most labs give a raw count and a counts/cubic meter. The latter number is an extrapolation depending on the amount of air drawn into the air pump. If 10% of a cubic meter was drawn in, then you would multiple the raw count by 10 to see what that equated to in a cubic meter.

It's easy to compare the raw counts for Aspergillus/Penicillium, which are marker molds for dampness, water damage, cross-contamination. If the raw are low, in the low single digits, there may be no red flags from the air samples.

I should point out that the better way to do air samples is called "aggressive sampling" and involves stirring up some dust. Many inspectors set up tripods for passive sampling and get undercounts for mold or miss it completely.

If raw counts are 20 – 30 – 40 and on up, there's likely an issue that has to be ferreted out. Tape samples are one important tool for finding sources of mold growth.

Also look at three other molds, the ones that are associated with floods, prolonged leaks, etc.: Stachybotrys, Chaetomium, and Trichoderma. If you don't see any of them, good. If you see some, where was it wet for a week or more – where mold spores have access to room air?

6. What is a good HEPA vacuum for dealing with mold?

A low-end HEPA vacuum with a good filter and commercial motor is the Euroclean GD930 – see on Amazon, for around $400. One client found it for less, with faster delivery, at www.jendcosafety.com. This model is used in mold remediation. A weak spot is the placement of the filter before the motor, so, even though all the dirt vacuumed up goes through the filter, the motor gives off its own dust.

When a HEPA vacuum cleaner’s exhaust airstream is measured with a laser particle counter, numbers should be very low. With this vacuum – as with all vacuums where the filters are before the motors – levels will be elevated – yet it is still a HEPA vacuum cleaner.

You might also check www.jondon.com, which sells supplies to remediators and has helpful technical assistance.

7. I want to do the remediation job myself but am not sure how to set up negative pressure and containment

Check out www.sunbeltrentals.com. They are all over and rent equipment such as negative air machines (which are air scrubbers that discharge to the exterior). They generally have good customer service for homeowners.

8. What products do you recommend for cleaning and encapsulation?

Send me an email and I will forward some remediation guidelines to you. If you are doing the job yourself, I'll also send some photos of an attic remediation job sent by other DIY clients. These clients sprayed on 9% hydrogen peroxide (diluted from 27% hydrogen peroxide from a swimming pool supply store) and the mold sizzled and fizzled and pretty much disappeared. Then, when the area was dry, they were planning to spray regular paint as an encapsulant.

STRONG POINT: Wear goggles, an N-95 or P-100 respirator, and protective clothing as needed when working with mold. Some common Aspergillus/Penicillium species can grow in sinus and lung tissue, and some mold particulates can cause severe allergic reactions. Take care that mold particulates not be breathed in.

9. An ERMI (or shortened HERTSMI-2) test was done in the dust at the house. The score was too high. The inspector says the house needs extensive remediation. I am freaked out.

Hopefully what is written below will help you see this in better perspective.

One mold-literate guy, looking for a new home, told me that he did 25 ERMI tests. 24 of the 25 houses failed. The only one that passed was brand new construction. Maybe the fault is with the sensitivity of the ERMI test, where a single spot can make the whole house sound bad.

Houses are not sterile environments. Just about all show some "issues." With ERMI, you have paid your money, learned that you don't live in a sterile environment, and still don't know where the mold is growing … and now you are being quoted $40,000 in remediation? And you have to get rid of most of your possessions? What's wrong with this picture?

Friends, ERMI (and other similar tests) are being used every day out there to justify recommendations for expensive remediation. Beware. Take a few breaths before you sign anything or move out.

Here are some things to consider:

  1. The EPA paid to have the ERMI test developed as a research tool. If you put the question to the EPA.gov website, Should I get an ERMI test at my home?, the answer will come back not to. ERMI would not stand up in court, according to what a doctor reported was told him by one attorney.

  2. When ERMI is being used, it rarely is being used according to the EPA protocol….which is to vacuum a square meter of carpeting according to prescribed procedures and collect the dust.

  3. ERMI can make a good house sound bad (because it is so sensitive that a small amount of mold can skew the whole test) and a bad house sound good (because it doesn't pick up on hidden mold, and most mold growth is hidden).

  4. There are professional questions about how the ERMI and HERTSMI-2 test are scored. (At one indoor air conference I attended, a joke was that the HERTSMI-2 test was aptly named, Hurts Me, Too.) I have a slide presentation analyzing the scoring (and other issues) of popular types of mold testing, by Joe Spurgeon, PhD. Just send me an email if you'd like a copy emailed to you. Dr. Joe is an expert witness in mold cases – www.expertonmold.com – and a valued mentor.

  5. Many people think the numbers in the ERMI and HERTSMI-2 reports refer to spores. They do not. They refer to "spore equivalents." That is, if one spore (or branch-like structure of mold growth, known as a hyphal fragment) dries out and disintegrates into 100 little bits and pieces, those bits and pieces count as "100" on the ERMI/HERTSMI test. If it breaks up into 500 little pieces, they count as 500.

  6. ERMI may have some internal miscalculations. There is risk that some molds that are found in Column 1 (such as Aureobasidium and Wallemia) belong in Column 2, and vice versa with Alternaria. Alternaria growth is linked with asthmatic reactions. Yet as Alternaria counts go up, the ERMI score goes down.

  7. ERMI/HERTSMI-2 misses a lot of mold. ERMI has fewer than twenty species of the marker molds for Aspergillus and Penicillium combined. HERTSMI-2 has a mere 2 for Aspergillus and none for Penicillium. These tests don't check molds; they reflect moisture conditions that might result in mold growth.

    Here’s some news. For a fraction of the cost of ERMI and HERTSMI-2, you can get a screening for all 400 Aspergillus/Penicillium species. You wouldn't get numbers for individual species, just a cumulative number. I mainly use this test (see Assured Bio attachment) on an AC supply vent cover. At least this way, if there are elevated numbers, I know where they are coming from, i.e., upstream in the central air system. (I use the $85 version of the test – see Assured Bio attachment.)

  8. Here's a story from a client in Brooklyn. The owner has a 100 year old house, a big house. So, before the man calls me, he knows he has a mold problem in two bathrooms and calls a local remediator. The remediator tells him that in New York State, an inspector has to write up a protocol before he can do anything. The remediator gives the homeowner the name of an inspector.

    The inspector comes in (as reported by the homeowner), walks around, does no testing, charges him $800 and says he has to return to do more extensive testing. (I already know of these inspectors and similar services – figure $5,000 - $8,000 for the more extensive testing.) Then the inspector remarks, "I can already estimate that remediation here is likely to run in the neighborhood of $300,000."

    Whereupon the homeowner calls me, having heard me on the radio twenty years ago. He tells me the story and says, "I smelled a rat." Love those Brooklyn guys!

    I come out to the house. A small area of new wood in the basement needed to be painted, followed by in-depth cleaning. In addition to the two known bathroom leaks, a third area upstairs was found to need remediation. In-depth cleaning was needed throughout the house. I referred the man to a professional remediator who would do the right thing at the known areas of mold contamination, for a fraction of the $300,000 and suggested that he sign on with a cleaning service for an in-depth cleaning and then routine, monthly cleaning.

    When housekeeping is minimal for extended years, of course ERMI would show high levels of mold particulates. It would be a minor miracle if it didn't. The house needs the regular services of professional cleaners, with the few areas of requiring remediation.

    Some would object. "But there are inflammatory particulates throughout the house! The man's health will never improve as long as they are present." Yes, of course there are inflammatory particles throughout the house. The house had not been thoroughly cleaned in years. Just about everyone's house has inflammatory particles throughout it, hopefully on a lower level. They are called dust, and they are why we want responsible housekeeping, preferably with quality HEPA tools.

  9. Where is dust being collected for an ERMI test? At one pre-purchase inspection, I pointed to the mucky area where a refrigerator had been taken out. The purchasers understood that if a dust sample for ERMI were taken from there, the whole house would look like it should be knocked down. Dr. Joe Spurgeon has said many times, "Presence does not equate to exposure."

    A colleague told me a story about his relatives. An inspector came in, did an ERMI test, and recommended extensive remediation. The colleague, a mold inspector well regarded in the industry, knew the house, knew it was a good house, and stepped in. He called the inspector to see where he took the sample for the ERMI test. It turned out the sample was taken by swab from an area of mold growth/discoloration. Then my colleague called the lab director where the ERMI was analyzed and asked about this. "This isn’t the way to take a sample." As my colleague told me, the lab director responded, "I know. I’ve spoken to him about that, but he keeps doing it." My colleague said to me, "Someone should sue that inspector."

  10. The points being made is that some of these tests (ERMI, HERTSMI-2, endotoxins, actinomycetales) are so sensitive and that mold, bacteria, etc., are "everywhere" … that test results can be used to frighten people and convince that they should get expensive remediation done.

    Are these test results ever valid? Of course they are. That's not the point. The point being made here is that there are often ethical concerns with how the test samples are being taken and how the results are being used.

    If you put your money into making your home healthier – you ultimately won’t have to worry about mold, bacteria, or actinomyceles….or test for them.
    (Actinomyceles – some other kind of microscope organism to worry about?? Avoid a common source: cool mist or ultrasonic humidifiers.)

  11. I like to keep things simple:

    i. Find the mold – through tape samples (and extensive, aggressive air sampling, if I am on-site)

    ii. Safely get rid of it….rather than having an extensive remediation when you don’t even know where the mold is growing.

    iii. Keep the mold from growing back through encapsulation.

    iv. Address the central air system – testing, treatment, and prevention against future issues – see the Assured Bio and Ventilation attachments.

    v. Have a good HEPA vacuum cleaner. Get rid of clutter. Damp-dust. Avoid carpeting. Make the house easy to keep clean.

    vi. Invest in your home, not in making the labs richer.

10. My doctor had me do a urine test, and mycotoxins were found. She thinks they may be coming from my house.

Mycotoxins are toxins given off by some molds under some conditions. Some doctors are ordering urine tests to get mycotoxin levels. These tests are controversial. The assumption (promoted by some labs) is that if mycotoxins are found in the urine, the house is the source.

One doctor remarked to me, "I don’t know if mycotoxins come from food or from the environment. All I know is that as levels go down, my patients are feeling better."

Mycotoxins are the doctors' area. There can be other factors contributing to elevated mycotoxins, such as food, sinus infections, etc. But if, for your own peace of mind – or your doctor’s peace of mind, you want to test your house for mycotoxins, there are two labs, that I know of, assessing dust samples (or parts of AC filters) for mycotoxins, EnviroBiomics and RealTime Laboratories.

Let’s spent a moment reviewing the instructions for taking dust samples for mycotoxins. There’s a big difference between what these two labs tell you to do, and it’s important to know what it is.

Envirobiomics tells you to do regular dust samples, not to sample visible mold or water-damaged areas. Real Time Lab tells you the opposite: sample visible mold. Which lab do you think finds more mycotoxins? But let's repeat what Dr. Joe Spurgeon said: "Presence does not equate to exposure." Unless you stick your nose into mold growth or into water damaged areas, you are not likely to be exposed from these areas (unless you or someone else stirs up the dust unwisely).

I recommend that you sample where you would have exposure. Sample the dust on tables, shelves, and surfaces that you are around a lot. Do a swab sample from the floor by your bed or sitting area. Sample at an AC supply vent. Don’t sample places where you would have no exposure, such as on tops of doors, under refrigerators, etc. Sample new dust, not old dust.

I’m not very experienced with either lab, but of close to twenty homeowners who have so far sent dust samples, including from the AC filter, to either one of these labs, no reports have come back positive … not to say it can't happen. One client with a horrendous AC system tested inside the inner ductwork before having the whole system removed. She found a low level of a few mycotoxins in the AC system but none in room dust – and that was worst case scenario.

Let’s think a minute about mycotoxin characteristics:

A. There are hundreds of mycotoxins. They mostly have been studied relating to contaminated feed that makes animals sick, though more human studies are underway.

B. Mycotoxins are chemicals – not bits and pieces of DNA – that are made by certain molds under certain conditions. Mycotoxins are not volatile, i.e., they don't float off into the air.

C. Dr. Joe Spurgeon was quoted above as saying, "Presence does not equate to exposure." So how would mycotoxins get from where they are produced to your lungs?

Imagine this scenario: There is a ton of mold hidden in a wall cavity. Joe Schmo comes in and tears down the wall, spreading dust and dirt and mold particulates everywhere. You breathe in the dust which contains mycotoxins.

Sound familiar? I thought not. This scenario doesn’t fit most of the houses I inspect. So where else might the mycotoxins come from? Well, maybe it's not the house. A staff member, from one of the labs mentioned above, told me they rarely find mycotoxins in their dust samples. At the other lab, when I mentioned that 20 of 20 of my clients had not found mycotoxins, the staff member said that maybe adequate samples weren't being submitted.

Fair enough. For sure, I’m not telling people to sample visible mold or to sample in water-damaged areas. I’m not out looking for trouble. We know those areas have to be properly cleaned. I want to be realistic and sample where people would be exposed, i.e., from nearby surfaces and from the AC supply.

D. If you want peace of mind that your house is not the source of mycotoxin exposure, do one of the dust tests for mycotoxins. Sample "newer" room dust that you might be exposed to, as well as, if you wish, sending a 2” x 2” square from your return filter.

Real Time Labs accepts three samples for the one fee – and gives just one report for all three. EnviroBiomics accepts one sample, a gauze pad, sampled from multiple areas.

E. Bear in mind that you could be living in a moldy house which is definitely affecting your health … and still get a negative on the mycotoxin dust test. Conversely, you could have a high level mycotoxin test and not have any mycotoxins or mold in your mold. You don't want to get fixated on mycotoxins at the house.

Keep it simple: find the mold, safely get rid of and keep it from coming back, have good housekeeping tools and good housekeeping. Test/address your central air.

11. Mold exposure indicated in a blood or urine test

From time to time, I get a call from someone who is freaked out, because a blood or urine test indicated mold exposure. They think that means that mold is growing in their body. No, the urine test just registers chemicals, and the blood test registers either antibodies to mold or perhaps inflammation levels that might be affected by exposure to mold. It is common for mold to be growing in the body, but more often it's a sinus issue or systemic candida. In contrast, here’s a story about someone who had Aspergillus growing in his body:

I got a call one Saturday night maybe 15 years ago or more. A young man had had a job as an energy rater, where they do measurements at AC vents – closing them, opening them, etc. He must have found my website and called out of the blue, with these words, "You should know my story."

He said that no one told them, the energy raters, that they should wear a respirator when doing their work at AC supply vents. He mentioned climbing a ladder to reach vents high up. Along the way, he must have inhaled a lot of Aspergillus from some nasty AC systems. Some types of Aspergillus can grow in human tissue, more often a type that prefers heat, which makes me think the AC units that bothered him were in the attics.

First, the headaches started. They got so bad that his doctor did whatever test, and fungal growth was discovered in his brain. He was operated on and the growth removed, but he was left with epilepsy. Then the mold showed up in his lungs. At the time of his call, he was on the most potent anti-fungal that, at that time, had recently been approved by the FDA, something called V-Fend.

The problem with anti-fungals is that what hurts mold, hurts us, because we are made of the same compounds as mold is. How is that man doing today? Is he still alive? I have no way of knowing.

With all the attention to Stachybotrys, I have long thought that Aspergillus got short shrift…especially after hearing this story. But no, friend, this type of infectious mold isn’t likely to be growing "everywhere" in your body.

So what do elevated mycotoxins in a urine test really mean? They mean that the kidneys are filtering out mycotoxins from somewhere – maybe from food, maybe from inhaled mycotoxins that got into the blood stream, maybe from being stored over the years because of a deficient detoxification pathway. Maybe the kidneys are just doing their job. Please refer health-related questions to your health care professional.

12. Here is a "if-all-you-have-is-a-hammer, everything-looks-like-a-nail" story

I got a call from a guy who bought a 100-year-old townhouse and complained that when he entered the townhouse, he got a headache, brain fog, and couldn’t sleep. He was fine outside the townhouse.

He had had mold remediation done, but his symptoms did not change. He assumed that mold had to have been missed, so he called me to find it. I checked for mold, formaldehyde, and gas leaks – and found nothing. I asked him to turn off his wireless router. Voila. The pressure in his head let up.

He called me a week later to report that he had hard-wired everything. His headaches and brain fog had stopped, and he could sleep.

It isn't always mold. See the attached, "Wireless to Hard-wired." Bear in mind that some routers, such as Comcast, are not off when you think they are. I had to switch out my Comcast box for a different modem and router – but that is written up in the attachment.

13. Other environmental issues

Other clients have been affected by environmental issues they (or their parents) never dreamed of and which did not turn out to be related to mold:

A. A 5-year-old stopped bedwetting the night the voltage was reduced at her bed – see createyourhealthyhome.com, the EMF tab, the body voltage tab, for instructions on how to measure/reduce.

B. A 4-year-old started sleeping through the night when a wiring error was fixed and voltage was reduced at his bed.

C. A woman could work again in her basement office once gas leaks were repaired. She had thought the problem was mold.

D. A woman was on the highest level of asthma medication and assumed the issue was mold. It turned out that the vacuum cleaner used by the cleaning service was spreading dog dander from house to house to house. She was severely allergic to dogs. Once she provided her own vacuum to the cleaning service, she stopped her asthma medication within a week.

E. A woman’s cough was 80% better within one week after getting a quality HEPA vacuum cleaner.

F. Many homeowners don't realize that carbon dioxide levels double/triple or more in tight homes with no ventilation. Some studies show mental sluggishness/dysfunction at 1,000 ppm, compared the less than 500 ppm of outside air. See Ventilation attachment.

Most of the houses I inspect measure around 1,000 ppm, with some over 2,000 ppm. I am updating this piece from a motel room where the levels were 1,300 ppm. I was having trouble staying awake - until a kind woman from the front desk showed me how to open the windows. Yea! That made all the difference. Those windows will be open until I leave here. Plenty of my clients' homes are at levels close to this stuffy motel room. They put the AC on and think they are getting better air, but central air just re-circulates the same old air, with the same old carbon dioxide levels.

G. A woman's itch stopped once the laundry detergent was changed. Branch Basicswas recommended. You might explore that website, because it gives valuable information about healthier substitutes for common household products. The co-founder, Marilee Nelson, wears a second hat as a consultant in least toxic building materials for folks renovating or building a new home. Her information can be found in the attachment, Resources: Indoor Air, scroll to Healthy Building Consultants.

H. A woman was surprised that her common free-and-clear laundry detergents set off the formaldehyde meter.

I. Homeowners had no idea how toxic their plug-ins made the air. When the formaldehyde meter alarm went off in their bathroom, within ten minutes all the plug-ins were gone from the house.

The meter went off at 0.30; many houses are at 0.15 or 0.20 – more than halfway there. Often pressed wood in kitchen cabinets or pressed wood shelves are a source. Formaldehyde off-gases forever. A speaker at the 2021 Indoor Air Quality Association's annual (on-line) conference commented that in a typical kitchen, with – say – eight cabinets with pressed wood shelving, figure 11 pounds of formaldehyde. You heard that right. 11 pounds.

If I were buying flooring, I’d see what Lumber Liquidators had to offer, because their flooring is formaldehyde-free (thanks to a class-action lawsuit against them). They get some products from the European Union, more stringent than our regulations.

J. Hot water temperature was measured with a meat thermometer at the kitchen sink … way below 120 degrees because the establishment of the 55+ community was concerned about scalding. The plumbing code calls for 120 degrees at the faucet in order to kill legionella bacteria in the hot water heater.

K. A woman started getting migraines from being in new buildings. Doctor said, "Formaldehyde exposure, but the underlying issue is mercury toxicity. Get rid of the mercury, and the body will handle the formaldehyde." She had her silver amalgams removed; he guided her in a type of homeopathic detoxing. It took 2 years for the headaches to stop, but it has been over 20 years since she last had a migraine.

Incidentally, mold can give off aldehydes, so there is a link between the mold and formaldehyde.

L. A doctor, the husband of a mold sensitive client, told me that he had improved sleep once they moved from their moldy house. He was surprised to learn that he, too, apparently was sensitive to mold.

15. Other resources, some of the many

a. My House Is Killing Me, 2nd edition, by Jeff May – also available on Audible

b Microwave News – sign up for free notification of research findings relating to health effects from exposure to wireless radiation

c. Electric Hostage: Knowing Our Enemy Can Mean Survival, by Sal La Duca – more of the theory behind electrosensitivity, for electricians as well as homeowners – www.emfrelief.com.

d. The Non-Tinfoil Guide to EMFs: How to Fix our Stupid Use of Technology, by Nicholas Pineault – more of a popular level book

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Next, Understanding Lab Reports, or, back to the Mold Topic Index.


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