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Photograph of Allergenco Mark III Impaction Air Sampler Airborne Mold Test Accuracy FAQs#2
Accuracy of Air Tests for Mold

  • POST a QUESTION or COMMENT about the accuracy and reliability of mold tests that purport to check a building for mold contamination levels or mold safety

Recent FAQs about the accuracy of air sample tests for mold contamination.

This article series offers an simple tutorial which provides information about the accuracy of and sources of errors in tests for the level of allergenic and toxic mold in residential buildings.

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Accuracy & Validity of Viable and Non-Viable Indoor Fungal Spore Counts & Cultures

Air test for mold, particle trace variation (C) Daniel Friedman

These questions and answers about the accuracy and thus reliability of various mold tests and mold counts were posted originally at ACCURACY OF AIR TESTS for MOLD - please review the discussion there.

On 2018-12-12 05:32:47.896484 by Anonymous


Thanks, and yes, I understand. But I was hoping some labs have better reputations than others, in part, because of stringent training and standards for their technicians.

On 2018-12-12 04:05:58.074795 by (mod) -

All of the labs use certified technicians and procedures. In my experience everything depends on the specific technician who actually does the work. There may be some variation from one Tech to another. After all it's not the whole Lab with its hundreds of employees it's one employee doing the work.

On 2018-12-11 22:50:42.211702 by Anonymous


Lab question: Do you have any impressions about EMSL lab and/or SEEML lab? If so, would love to hear. Thank you!

On 2018-12-12 by Anonymous

Thanks, and yes, I understand. But I was hoping some labs have better reputations than others, in part, because of stringent training and standards for their technicians.

On 2018-12-12 by (mod) - impressions about EMSL lab and/or SEEML lab?

All of the labs use certified technicians and procedures. In my experience everything depends on the specific technician who actually does the work.

There may be some variation from one Tech to another. After all it's not the whole Lab with its hundreds of employees it's one employee doing the work.

On 2018-12-11 22:50:42.211702 by Anonymous


Lab question: Do you have any impressions about EMSL lab and/or SEEML lab? If so, would love to hear. Thank you!

On 2018-12-03 22:21:41.866107 by Anonymous


Thank you! You have been more thank kind, patient, helpful, and exceedingly generous with your time!

On 2018-12-03 by (mod) - 4 orders of magnitude in "mold counts" stem from very small test procdural changes

3 possibly

I have said repeatedly throughout these articles that small changes in how a measurement is made and in measurement conditions can make 4 or more orders of magnitude difference in a "spore count" of airborne spores (or of other airborne particles)

So 5000 means the "true" number could have been 5 or more than 5 million.

On 2018-12-03 by Anonymous

1. Thank you. I made an error. Just checked the lab report and there were 0 hyphal fragments in the indoor samples. (9 in the outdoor sample.) So I guess that's a shred of good news.

2. Thanks for the info on labs and spore chain reporting. It will save me from trying to find the impossible!

3. Do you think it's possible (hypothetically) that disturbing a 12"x6" area of dead mold could release so many spores as to skew a test result such that it would be 5,000? I realize there are many variables.

I just want to know if you think this one variable could impact the result in this way. I realize it's hypothetical, but based on your knowledge, is it a reasonable possibility?

4. Thanks so much for the recommendation for how to handle the rear wall. It's very helful to have such guidance.

Your suggestion will spare us from doing too little and it being a waste and, perhaps, doing too much with no evidence to support ripping the entire wall out at the get go.

THANK YOU, THANK YOU, THANK YOU!

On 2018-12-03 by (mod) -

1. No. The opposite. That is if I'm finding highfill fragments in any quantity and indoor air I suspect there's a nearby mold Reservoir although the specific species suggested such as cladosporium may not be the species that would be of most concern.

2. Probably most Labs don't report Spore chains and of course I wish they would. It's a level of sophistication in thinking that escapes some of the high volume High profit outfits but I don't assume that a boutique lab is necessarily more careful.

You really need to look at data in a number of ways and no lab test is ever a substitute for an expert on site thorough inspection and interview and history taking Etc when assessing a mold problem at a building.

3. Exactly right. Even within a specific Jenner and species of mold that propensity to release spores varies enormously depending on changes in local conditions besides are disturbance such as changes in temperature and humidity.

4. Boring very small diameter holes even looking with a scope into those holes is not as reliable as cutting a larger opening such as a two-by-four in opening that allows you to inspect more accurately and also to look at the condition of the back side of the drywall.

Where you would cut exploration openings would be in the most suspect locations. That's based on other Visual Evidence and building history at cetera.

On 2018-12-03 17:53:56.599156 by Anonymous


OK, so not to be No Good Deed Goes Unpunished (!) I have a few more questions. If you would be so kind as to answer them I would greatly appreciate it:

1. Do you agree that a low count of hyphal fragments indicates reduced likelihood of active mold?

2. I appreciate the importance of knowing if the lab sees spore chains or not (at least w/respect to Asp/Pen) and wonder if this info is not provided on a lab report if I should consider that a less-than-reputable lab?

Related to that, do you have any guidance about how to vet a reputable lab or even labs you specifically recommend (or don't recommend)? If you've already written about this, my apologies. There are so many links here including links within links that I found myself down some rabbit holes and wasn't sure how to get back!

3. I've also come to appreciate how different types of spores have different properties and how that impacts the meaning of numbers. You have made numerous comments about Asp/Pen that have provided a lot of insight

I'd like to know if you think that disturbing a small area of dead Asp/Pen mold (12" x 6") pulling away insulation that revealed the spot and then running a spore trap test right next to that location could, conceivably, produce a count as high as 5,000. (I understand there are many variables that impact counts, but these are two variables (disturbance and proximity to testing equipment) and would like your opinion on this.

4. If the mold inspector thinks there could be mold behind a basement wall based on the 5,000 Asp/Pen number and the observation of a few very small, old stains on the wood (not wet, moisture meter not triggered, nothing visible observed,

just trying to sleuth the reason behind the number) would it make sense to do a few tests by boring small holes in that wood or is that too risky in that you'd have to be lucky enough to hit the right spot to get numbers that meant anything? Same goes for extracting samples from random areas of insulation? Any value to help determine what might be going on?

THANK YOU!!!

On 2018-12-03 16:55:32.968907 by (mod) -

Glad to assist.
Working together makes us smarter.

On 2018-12-03 04:59:33.688452 by Anonymous


Thank you, Dan. Your generous sharing of your amazing wealth of knowledge is so very much appreciated!

On 2018-12-02 12:34:47.543571 by (mod) -

I agree that if you are performing demolition that creates potentially harmful dust you'd want to prevent cross contamination out of the work area.


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