Using Mold Plates (The Right Way) to Monitor Indoor Fungal Load and Protect Your Health

by Catherine Fruechtenicht

On my blog Mold Free Living, I often share how I use inexpensive mold plates to test the air and different pieces of furniture and belongings in our home for mold. I use these plates to keep a constant eye on mold levels and to make sure our exposure is not increasing. I always like to rule environmental mold out as the cause for any inflammatory symptoms or autoimmune flares (I acquired ulcerative colitis during my battle with mold toxicity) that I may experience. There is always a strong correlation for me with my health status and the fungal load in our home now that my body has become sensitized to mold. My threshold for all environmental toxins is much lower and even a little mold exposure can be a LOT for my body if you know what I mean.

What is Fungal Load and Why Should You Care?

“Fungal load” is a term that I got from Dr. Dennis and is used when he is discussing fungal infestation in a patient and his/her environment. Allowed to go unchecked in the body or environment, fungi can and usually do replicate–make copies of themselves–which causes the overall amount of fungi or fungal load to increase. That is why keeping the fungal load low in your home can help you to maintain your health. Counting the mold colonies that form on a mold plate after testing the air or after testing clothing or belongings does just that–measures, in a rudimentary but straightforward way, the immediate fungal load at that point in time.

After treating thousands of patients with allergic fungal sinusitis, Dr. Dennis began testing their clothing and nasal cavities for fungus in his office. He found that the high levels of mold spores on their clothing were directly related to the species of mold also found to be inflaming and causing infection (chronic infection for many) in their sinus cavities. Further, when he sent those same patients home with mold test plates to also test the air in their homes, they found high indoor mold counts or a high fungal load in the rooms in their homes where they spent the most time. It was a correlation (high environmental mold equals increased instance of chronic sinusitis) confirmed by more in-depth environmental and mycotoxin testing, but an undeniable correlation nonetheless, and one that he was able to chart and track overtime clinically to come up with some pretty solid guidelines for his patients as far as mold plate testing is concerned. It is Dr. Dennis’s guidelines from which I base my own baselines when I monitor my home today. (Keeping the mold counts in the air and on belongings at 0-4 colonies is ideal for continued health and recovery.)

Why Test at All With Mold Plates?

Let’s not beat around the bush–mold plate testing is definitely not the beat-all-end-all diagnostic for an indoor mold problem; gravity test plates should not be “the tool of choice” or used as the only gauge for whether a home has a mold problem or is “safe” or not. They are just an easily accessible, inexpensive option for someone wanting–

1.)  To see IF their home and/or belongings have elevated levels of mold,

2.) To see WHERE or in what areas or rooms those elevated levels of mold might be, or

3.) To obtain a fungal load baseline so that a mold-sensitive person can monitor their environment.

I use mold plates for #3, and they work well for that purpose at a price that doesn’t break the bank. Then, if I suspect a larger problem, or see trends of an elevated fungal load in the air or on our belongings that do not decrease with normal cleaning and mold maintenance, I can do mycotoxin testing or can call an indoor environmental professional to help me diagnose and solve the problem before it gets out of control and/or wrecks my health.

How to Properly Use Mold Plates

In order to help you understand the most effective ways to use the mold plates for screening your air and belongings, I thought I would share a very simple “how-to” on how I use them in my home. I will walk you through using the mold plates to test your air and to TAP test your things. I will also share links to further testing methods like mycotoxin and ERMI test kits and professional inspection resources that can be used to find out your potential exposure risk in your current environment to the more toxic and water-damage indicating molds.

Using Mold Plates for Air and TAP Testing

I have found that in order to stay well, I need to keep mold plate counts at 0-4 colonies per plate with a 1-hour plate exposure for air testing and 0-4 colonies per plate for any TAP test performed on my belongings/clothing/furnishings. This is key for me and my body. Unless my indoor environments are kept at this level, nothing else works long term for me. I must breathe clean air in order to get well and to stay well. Period. You could definitely be different, but, if you are mold sensitive, you are likely going to need to keep things at a similar level.

(Note: To obtain the most accurate information possible, you will also need to record the humidity in each area tested. If the humidity is higher than 50%, any ambient mold spores that are inside your home have the level of moisture needed to land and proliferate. This is also why cleaning with mold-specific products, keeping dust to a minimum, and HEPA vacuuming are so important to maintaining your home and your health.)

Performing a 1-Hour Air Test:

Preparation: I like to refrigerate my mold plates upon receipt and use them as soon as possible. Pay special attention to the expiration dates and do not use expired plates to test. Do not open the mold plates until you are ready to use them.  Keep windows closed for six hours prior to testing.

Do what you normally do. For example, do not turn on the air conditioning unless that is part of your normal activity. However, DO place the central fan on the heating and air conditioning system in the “on” position. Do not sweep or vacuum just before the test since this activity can increase the number of mold spores that are in the air. Children and pets can continue to be in the areas being tested, but do NOT allow them to touch the materials. The main thing is to ACT NORMALLY. Select an area to place the mold plate that is at least 3 feet from a wall. Use a humidity gauge to test the humidity in each area. If humidity is really high (60% or above), you will need to disturb the air in the room a bit to get mold spores to become airborne. High humidity will cause them to stay on top of surfaces.

Suggested Areas for Sampling: Locate the area or areas that you wish to test. If specific areas cause sneezing and coughing, or noticeable symptoms, they should be included. At a minimum, please be sure that at least one mold plate is placed in each of the following areas:

Attic Basement Master Bedroom Den/Great Room Car Kitchen Child’s Bedroom Office (home & work) Other active rooms – In large homes, place 2 plates in the basement & attic

It is not necessary to place mold plates in rooms that are not used. It is necessary to place plates in rooms that have odors–musty especially, if symptoms occur in that room, or if there is a history of water damage in that room. Do not place any mold plate in direct sunlight.

Directions for Air Testing:

1. Carefully unwrap the materials. Do not touch the inside of the test plates.

2. Place the plate on a tissue or paper towel in the room you wish to test. The top should be up and is the larger side of the test plate.

3. Lift the top straight up. Place the top on the tissue with the inside surface down. Do not turn the top upside down.

4. Allow the plate to sit open for one hour.

5. Put the top back on the plate. Tape the top closed.

6. Write the name of the room, the humidity level, and the date on the bottom of the plate with a permanent marker that writes on plastic. Use descriptions like attic front, attic back, master bedroom, downstairs playroom, crawl space, etc., so the results can be easily tied back to the correct areas of your house.

7. Wrap everything in aluminum foil. Several plates can be wrapped together.

8. Place wrapped plates in a warm, dark spot, such as a kitchen drawer for 4 days. (Note: My 4-day incubation period guideline may be shorter than what is advised with some test plates. I find 4 days to be the ideal time for allowing the mold colonies to grow.)

9. On the 4th day, unwrap but do NOT open the plates. Count the circular colonies present on each plate. Each circle represents a mold colony. You ideally want to have fewer than 4 on each plate. Here are some examples of mold tests I have done recently in our home with acceptable results:

Here is an example of a TAP test plate with unacceptable results due to some contaminated carpet in a bedroom that needed to be removed:

But, this is also the reason why you test the air AND TAP test–which I will explain in a minute. Because if just the air in this room had been tested, the mold counts would have likely been higher, but by ALSO TAP testing the carpet, the homeowner knew WHY and then could know WHAT to remove or fix to make the home healthier.

Directions for TAP Testing:

You will tap certain items, by opening the test plate and tapping the item with the media surface pointed down towards the item you are tapping.


The following items should be tapped for the clearest picture of fungal load:

■ Mattresses and Pillows ■ Carpet or Rugs that have frequent traffic ■ Clothes in your closet that you wear and wash frequently ■ Furniture that you sit in the most in your home ■ Pets ■ Desk or work table or area ■ 

Once complete you will follow the instructions above #’s 5 through 9. Make sure to label each plate accurately for the item tested. Again, the goal for mold-sensitive folks is to achieve test plates that only grow 4 colonies of mold per item in four days incubation time.

Digging Deeper

If you perform this type of testing and find that your indoor fungal load is elevated and feel that you have not pinpointed a reason, unlike the carpet example I shared above, I always suggest doing some deep cleaning, humidity control, and increased air filtration/purification. If a home does not have water damage or intrusion, this can sometimes be enough. If levels continue to increase despite cleaning and mold maintenance interventions, you will need to contact a qualified indoor environmental inspector (good resources are the American Industrial Hygiene Association, the ACAC, and the IICRC websites) or a certified Building Biologist to help you get to the root of the issue. You can also choose to go deeper with diagnostic testing like the ERMI, EMMA, or Mycotoxin testing. I do recommend contacting a professional first, though, to assist you in devising a testing strategy so that you not only come up with test results but also with a strategic game plan of how to fix the underlying issues causing the elevated mold growth and indoor fungal load and a clear, effective remediation strategy for your indoor air and belongings once those fixes are complete.

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