Does A Mold Air Test Really Work?

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When it comes to testing for mold, there are many options available. One such option is the mold air test also known as air sampling for mold.

There is a lot of controversy related to conducting an air test for mold. On the one hand, it typically is the only mold test that is considered admissible in a mold related lawsuit. It is also typically the only mold test that will legally allow a tenant to break a lease or rental agreement. Therefore, it has become somewhat of a standard when it comes to testing for mold.

On the other hand, mold air samples are highly unreliable and inconclusive making them a possible waste of valuable time and money. So what’s the deal? Should you conduct an air test for mold or should you use another mold testing option?

What Is A Mold Air Test?

It is exactly what it sounds like. It is a means of testing for the presence of mold by collecting a sample of spores in the ambient air.

There are several types of devices used to collect air samples that can be analyzed for mold.  The most common devices are:

  • Impaction samplers that use a calibrated air pump to impact spores onto a prepared microscope slide.
  • Cassette samplers (which may be disposable or a one-time-use type) that employ forced air to impact spores onto a collection media.
  • Airborne-particle collectors that trap spores directly on a culture dish. 

How are Mold Air Test Samples Examined in the Laboratory?

Mold spore sample slides are prepared in the laboratory and then examined at magnifications from 100x to 1920x to identify the dominant or other indicative particles collected. Particle counting, such as spores/M3 of air, if provided, is performed at 400x, 480x, 720x, 1000x, up to 1920x.

Some companies also use polarized light and darkfield methods and a variety of slide preparation chemicals and stains.

Do You Need A Mold Air Test?

Not necessarily. There are other mold tests available. However, a mold air sample test can help to identify if elevated levels of mold spores are present in the air, which can be an indication of potential elevated moisture concerns.

Are There Federal Regulations Or Standards Regarding Air Sampling For Mold?

Standards or Threshold Limit Values (TLVs) for airborne concentrations of mold, or mold spores, have not been set. Currently, there are no EPA regulations or standards for airborne mold contaminants.

Where To Take A Mold Air Sample and Ideal Conditions

Air samples can be taken to help verify and gather more information in any areas of a house suspected or confirmed to have mold growth.  Moisture intrusion, water damage, musty odors, apparent mold growth, or conditions conducive to mold growth are all common reasons to gather an air sample. 

Samples typically should be taken near the center of the room, with the collection device positioned 3 to 6 feet off the ground.

Sampling should take place in livable spaces within the house under closed conditions in order to help stabilize the air and allow for reproducibility of the sampling and measurement.  While the sample is being collected, windows and exterior doors should be kept closed.  It is best to have air exchangers (other than a furnace) or fans that exchange indoor-outdoor air switched off during sampling.

Weather conditions can be an important factor in gathering accurate data. Severe thunderstorms or unusually high winds can affect the sampling and analysis results.  High winds or rapid changes in barometric pressure increase the difference in air pressure between the interior and exterior, which can increase the variability of airborne mold-spore concentration.  Large differences in air pressure between the interior and exterior can cause more airborne spores to be sucked inside, skewing the results of the sample. 

What Is The Cost Of A Mold Air Test?

That depends. The test itself can run anywhere from $70-$500. The fee depends on how many samples are collected, what kind of device is used to collect them, and what sort of laboratory analysis is being performed. Each mold testing company will have varying fees as well.

What Are The Pros Of Air Sampling For Mold?

1. As a screening mechanism.  If significant levels of airborne particles are found, which have not already been found by a visual inspection nor in bulk sampling it may mean that additional, more thorough or invasive building inspection is warranted.

But keep in mind that the absence of airborne particles in a screening check is no guarantee that problematic mold is absent in the building.

2. As a cross-check in clearance testing. Mold air testing may be performed after remediation to ensure that the mold levels have been properly reduced to “acceptable” levels.

What Are The Cons Of Mold Air Samples?

1. Mold Air Samples Only Give A Very Brief Snapshot Of What Might Be Going On In A Building

Mold air samples are typically collected for a period of 5 minutes (or up to 10 minutes depending on the mold inspector). This means that the sample only accounts for whatever happens to be floating around in the nearby air during that 5 minute time frame. This is an issue because the air around us is always changing depending on the level of recent activity in the home, whether the HVAC is running, if windows were recently opened, if the house was recently vacuumed, etc… In fact, you can collect a sample in the same location 20 minutes later you will get a completely different result.

Mold air samples are highly variable and do not provide a historical perspective of a mold contamination that has impacted the space. For this reason, their results often provide a false negative.

2. Fungal Fragments Are Not Accounted For In The Mold Air Sample

Mold colonies don’t only consist of spores. They are made up of entire growth structures which release spores as part of their metabolic process. Fungal fragments (pieces of these growth structures) can break away from the colony and become airborne. These particles carry the DNA of the mold colonies, and even carry mycotoxins making them critical to analyze as part of the mold testing process.

According to this study published in Medical Mycology, fragments of several fungal species are aerosolized in much higher concentrations (300–500 times) than spores. Leaving fungal fragments out of mold testing is a huge mistake.

Because fungal fragments are not spores, they are completely overlooked when analyzed as part of an ambient mold air sample. Therefore, ambient mold air samples only show a small piece of the overall potential exposure.

3. Air Tests Tend To Find Particles That Are Naturally More Easily Airborne

Stachybotrys chartarum is a large, sticky mold spore which is not easily airborne. These spores are not normally found in indoor air even if a large mold reservoir is present unless the Stachybotrys chartarum is being disturbed. This could occur by incompetent demolition and cleaning or by carrying very moldy items through a building. Therefore, a mold air test might come back as negative for mold when it fact there is a high level of stachybotrys in the building.

In comparison, Aspergillus spores are much smaller and lighter making them easily airborne by simple air currents.

4. Outdoor Mold Counts Are Tricky To Compare With Indoor Mold Spore Counts

Outdoor air samples are also typically taken as a control for comparison to indoor samples.  Two samples, one from the windward side and one from the leeward side of the house, will help provide a more complete picture of what is in the air that may be entering the house through windows and doors at times when they are open.  

Outdoor mold counts are tricky to compare with indoor mold spore counts because the same genera may be found but in fact there are several different species of that genera. For example, a lab finds aspergillus both in the indoor and outdoor samples. The lab says that there is a lower spore count indoors which in theory would be considered a good thing. However, the aspergillus inside is a completely different and more dangerous species than the aspergillus found outside.

Most mold labs cannot or do not differentiate to this level of detail. As you can see, this makes a comparison of these two spore counts meaningless.

5. There Is A Variation In Airborne Particle Levels Due To Placement Height Of Air Sampling Device

Many consultants and mold inspectors place their air sampler at about chest or head height in a building, presuming that will best represent the particles that will be inhaled by building occupants.

As we learned above, mold spores move around and down which means that at any given time there may or may not be spores at or above chest height.

There is a lot of debate about proper placement of an air sampling device but the general consensus is that somewhere around the 3 foot mark from the ground is ideal. Most devices are in fact placed around the 5-6 foot range.

Is There a DIY Mold Air Test And Where Do You Buy It?

There are. In fact there are three options. Let’s take a look.

My Mold Detective

My Mold Detective Air Test Kit

This kit uses the same technology as the mold air tests run by professional mold inspectors. You test the air in one or more locations in your home (plus an outdoor air sample as a “control”). Register your samples online, then send them in the prepaid envelope to My Mold Detective’s lab for testing. Then, you’ll receive a professional, easy-to-understand report that shows the types and levels of mold in your home and whether it’s time to contact a remediation specialist.

You can get a 3 room kit here for roughly $80. There is also a $35 fee per sample that is due at the time you register the sample.

Clean Vent Air

Clean Vent Air Solutions - Air Test Kit for Mold

Clean Vent Air offers a new and improved testing method with activator solution. It determines if the air from your air conditioner is contaminated. It also detects if mold is in your air conditioning unit or duct system.

You can purchase the Clean Vent Air kit here for approximately $25 which includes shipping.  There is also a lab fee of $40.00.

Home Air Check

Home Air Check Air Test Kit

Home Air Check is an advanced, accurate test. It identifies most major VOCs, formaldehyde, and growing mold that may be lurking in your home’s air. Only Home Air Check offers a professional-grade analysis at an affordable price with an easy-to-use test kit, a world-class laboratory, and easy-to-understand answers you can act on for cleaner, healthier air.

One Home Air Check test kit is $169 and can be purchased here. This will cover a 2,000 square foot home.

Are DIY Mold Air Test Kits Like My Mold Detective, Clean Vent Air, and Home Air Check Worth The Money?

If I already knew I had mold then I wouldn’t waste my money on it. If I thought I had mold and there was a possibility that I might get into litigation because of it, I wouldn’t use a DIY mold air test. If my budget was tight and I wanted to conduct a mold test that was reliable then I would run an ERMI test and not use any of these DIY mold air test kits.

It wouldn’t matter what DIY mold air test was available. The bottom line is that air sampling for mold is highly unreliable and not the best way to learn what is going on in your home.

For more information on other more reliable mold testing methods, please visit my Mold Testing page. Also check out all my Mold Prevention posts as well as my articles on How To Remove Mold.

A mold air test being conducted in a home

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  1. Alice Carroll says:

    Thanks for pointing out that I have to be very careful about the air sampling when getting a commercial air quality and mold testing service because of how dynamic particles in the air can be. I recently found a good commercial space where I can open my bakery business someday but the place feels a bit too damp for my own comfort. I think it would be for the peace of my mind to see if the place is prone to molds.

  2. Zoe Campos says:

    It’s good to know that a mold air test can be done to assess whether there are mold spores in one’s air at home or not. My sister has been having constant allergies despite staying at home for days. Maybe it would be a good idea to look for a mold testing company to check out her home’s air quality soon.

  3. Afton Jackson says:

    After reading this article, I can now see how much more complicated mold testing can be than what I previously assumed. This makes me think that I should really try and avoid any kind of DIY with this procedure since I lack the equipment for proper testing and will just expose myself to dangerous substances. I’ll take your advice and look for a mold testing contractor in the area as soon as possible.