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Why DIY Home Mold Tests Can Be Misleading - Part 2

08/30/2018 | Air Care Wizard

In our first installation of this series, we talked about the importance of including a control sample when taking air samples for mold in a home or business. We learned that context is important when determining whether or not we have elevated spores in a building, as mold is ubiquitous and makes its way into our homes frequently in non-problematic levels. Today, we'll discuss some of the types of mold tests that are utilized by industry professionals.

A cursory search of DIY home mold tests led me to a test kit on a large online retailer. A quick review of the information left me in awe of the misinformation presented. At best, the presentation of the information is disingenuous. As I stated in the part 1 of this series, different types of tests do different things. Without getting too deep into the minutia, we'll cover the basics below:


Air Sampling


Air Samples- Most air samples are taken with a spore trap cartridge that is connected to an air pump. The spore trap has a thin sticky material surrounded by a plastic casing. This trap gets connected to an air tube the pulls air through the trap, so that spores that make their way through will get stuck on the sticky material. The air pump is set to a specific setting to maximize the capture of spores on the trap. These tests are good for determining if there are mold spores present in the ambient air.


 Tape Lift


Tape Lift- A tape lift is a pretty basic sampling method. It's a thick, pliable piece of plastic that has a sticky portion on one end. These are used to test for settled mold spores on walls, above doors, furniture, etc. The tape lift sample gets put onto a glass slide and sent to the laboratory for review. May times, tape lifts are used to see if a property has been remediated properly as we can test surfaces where mold spores were initially present.


 Swab Sample


Swab Samples- Swab samples are much like tape lift samples in that they require the sampling technician to sample a particular surface, such as a wall or piece of furniture. The big difference is that swab samples are used to culture the mold spores that they capture. This cultured sample given us additional identifying information so that we can determine the particular species of mold. Air Samples and tape lift samples will only get down to the genus level. We'll save the lesson in taxonomy for another day. This is all to say that if you're allergic to a particular type of mold, swab samples will give us the most accuracy in determining whether or not that species of mold is in the home or business.


ERMI Testing Kit


ERMI Testing: These types of tests use collection of dust to identify mold in a property. Originally designed as a way to correlate childhood asthma with historical water damage information, ERMI tests use DNA analysis of the sample to identify mold types. The limitation of ERMI testing is that the results generally do not correlate with current conditions in the home. They are good for providing historical information regarding molds that were present in the home at some time. These tests are not indicated for consumer use.


It's important to understand the limitations and strengths of each of the testing methods as they have clear implications for the financial, mental, and physical well-being of the homeowner. A professional mold assessor would be unwise to utilize an ERMI test to identify current airborne levels of microbial spores. Conversely, that same assessor would also not be doing right by the customer if they utilized an air sample to gather historical data about molds that have been present in the home over an extended period of time.

With at-home tests, we may be utilizing a testing method that is not providing the type of information that we are looking for. We also lack the professional judgment of a licensed assessor to guide the process and interpret the results. Some at-home tests will utilize an ERMI-type dust collection test when the homeowner really wants to know why their child is getting sick so often. Unfortunately, this method of testing will not provide the correct answer to the question the homeowner is asking. It will provide an answer, but to an entirely different question. This is where interpretation of a test used for the wrong purpose may cause the homeowner undue distress. Using the proper testing methods with an assessor who can navigate the necessary procedures and methods is important for answering the important questions that customers are asking when we are dealing with microbial problems.

We'll continue this series in post 3, when we get into some of the claims made by at home test kits and we'll see if they hold up.