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How Many Mold Samples Do I Need?

mold air sampling pump attached to a tripod

If you have done some basic research into mold testing, you have probably come across information on air sampling. For this blog, I will focus on the most common type of mold air samples, spore traps. Each specific mold problem is unique, so there is no one-size solution for the number of air samples. The appropriate sampling strategy will try to find the intersection of budget and the amount of useful information. This blog also can not get into every potential situation, so we will be focusing on the “big picture”.

Minimum Amount of Mold Samples

Many low-cost mold inspections will typically only include one sample indoors, and one sample outdoors. However, this is not a standard industry practice. On the other hand, since each sample has an associated cost, how do you know that you are not taking too many redundant samples? One of the keystone guidance documents for mold professionals, Bioaerosols: Assessment and Control published by the ACGIH recommends that the minimum samples to be collected should be one sample in the area of highest concern for mold, an outdoor reference sample, and an indoor reference sample (collected from an indoor area with the suspected lowest concentration of airborne mold). In homes with a limited mold concern, or smaller condos and apartments, these three samples typically are the best

Additional Mold Air Samples

Now that we understand what the minimum mold air sampling strategy should look like, I will next discuss some situations that may call for additional samples. Large properties are typically a great example of when extra air samples can be very helpful. Since these homes can be sprawled out over many floors with multiple HVAC systems it is almost better to treat them as multiple units in the same property. Homes with multiple moisture and mold issues, or large issues that cover many different areas of the home could benefit from additional samples. Also, families that have sensitive individuals living in the home may want to test those individuals bedrooms in addition to the rooms of concern in order to have a clear idea as to if there is mold impacting the air quality in the areas they spend the most time in. Another situation that may call for more air samples is when you want to test inner wall cavities using wall checks. These specialized air samples are often best done in coordination with general air sampling. People who have a mold inspection performed during a real estate transaction may want to take additional mold samples, since often the history of the home may be incomplete it is best to spend a little extra on air sampling to have a clear picture in all areas of the home.

If you are in the Chicago area and have mold concerns, and would like to discuss your options, feel free to contact us. One of our experienced project managers would be happy to discuss your situation and give you an idea of what we can do for you.

Ian Cull

Ian Cull is a nationally recognized expert in the field of indoor air quality. He is the Chief Science Officer of Indoor Science, a company he started in 2004. He speaks around the world on air quality topics and is a training provider of the Indoor Air Quality Association. Mr. Cull is a Licensed Professional Engineer (PE) and Certified Industrial Hygienist (CIH). His degree is in Environmental Engineering from the University of Illinois - Urbana Champaign. Mr. Cull has developed 50 air quality related courses for the IAQA University and is the author of the book, “Fundamentals of Mold Remediation”. In his words… “Besides being passionate about indoor air quality, I enjoy cycling, music, the Chicago Bulls, and having fun with my three kids.”