Mold Testing Methods Compared

Mold testing has become more accessible than ever before. What used to be relegated to only professional inspectors has now become easier and more affordable so that individuals can test. We’ve summarized 5 of the most popular mold testing methods to allow you to make an informed decision to see if your home or business might be effecting your health. 

Comparing the Test Methods

We compare each testing method in the following areas: Sampling Approach. Collection Method, Analysis Method, Costs, and General Pros and Cons. Tap a button below to jump to that area.

Sampling Approach

Understanding how the philosphy in taking multiple samples greatly impacts the results.

Individual Samples

Individual Sampling collects samples for a specific area, for example, Gravity Plates and Spore Traps test each room individually of a home or office. Swab/Bulk/Tape Lifts test even a smaller area such as an HVAC register or potential visible mold on a wall.


Composite Samples

Composite Samples take one sample from multiple areas so the test cannot give information about any one room or area. For example, ERMI and HERTSMI samples are typically taken from a living room and master bedroom in the same collection canister or on the same Swiffer Cloth-like wipe.

Collection Method

The way mold is collected for each test method will significantly impact the discovery of mold. 


Airborne and dust mold tests are best for when you don’t know if there is mold present, as well as determining the amount of mold that is airborne, as inhalation is the primary route of indoor mold exposure.


Dust samples can be helpful in identifying heavily water damaged buildings, especially in detecting certian types of mold including stachybotrys.



Surface testing is best for determining if visible water damage or discoloration of building materials is mold related, as well as for the identification of molds that are growing.

Analysis Method

While collection methods vary, mold testing methods can be divided into two categories of identifying mold. 

Visual/Microscopic Analysis

Visual/Microscope Analysis involves a trained technician visually identifying mold based on colony growth characteristics, as well as identification of mold spores and other particles using laboratory microscopes. This is by far the most popular method of analysis as it is more cost effective and can detect mold from thousands of species.


DNA Based Analysis

DNA based detection is a chemical process which positively identifies specific mold species and is a fairly small fishing net that depends on detecting molds that are assumed to be indicative of water damage. While this is an exact method, it requires labor and time-intensive steps to get results.

Cost Comparison

Testing 4 Rooms

The different mold test methods each have their own unique uses, however, the focus of this comparison is on people conducting a test for their home or office. We have therefore compared what it would cost to uniquely test 4 rooms in a home. 


  • Gravity Place prices based on, Customized Mold Test Kit,  October 2020
  • Self-performed Spore Trap is based on, 1 Mold Test Kit, 4 additional Air Cassettes,  October 2020
  • Self test ERMI based on,  ERMI Analysis, and Dust Collector, October 2020.

General Comparison

Pros & Cons of Each Method

  • Inexpensive
  • Self-Analysis gives the presence of mold
  • Lab analysis can determine the largest number of species
  • Only identifies live mold (which is a vast majority of indoor mold)
  • Although widely used by doctors, gravity plates are not recognized as an industry standard

Gravity Plates are the gold standard for obtaining as much information as possible for a given budget. Gravity Plates provide a sample of mold spores suspended in the air, or can be used to test a variety of surfaces and materials through Tap Testing. Gravity Plates are conclusive as the petri dish incubates and grows the mold over time. The mold growth can then be analyzed visually for a snapshot of mold grown, or a laboratory can conduct a detailed microscopic identification of mold genus and species.

Immunolytics offers Gravity Plates and Swab testing with the Immunolytics Mold Test Kit. 


  • Inexpensive
  • Identifies dead and live mold
  • Best for visible or suspected mold on surfaces
  • Samples a relatively small surface
  • Does not provide an indication of potential health symptoms

Mold Swabs/Bulk/Tape Lifts can test hard to reach places such as air vents, HVAC systems, ductwork, windowsills, door frames, drywall, below carpet, and behind wallpaper. This form of testing is beneficial when mold is visible or suspected. The swabs have an absorbent microfiber tip that will gather substantial samples for laboratory analysis. Tape Lift samples utilize the glue on the tape to capture the mold spores and related mold fragments. Bulk samples are pieces of material on which mold appears to be growing (often drywall, wood studs, etc.). Their collection allows the laboratory to analyze exactly what is growing.

Immunolytics offers Gravity Plates and Swab testing with the Immunolytics Mold Test Kit.

  • Inexpensive per test cost
  • Industry-standard
  • Specialized equipment required
  • Short 5 minute sample time
  • Outdoor “control” mold sample recommended for comparison

Spore Traps are an industry standard method of testing for mold spores in air samples. They are a very brief snap shot of what is in the air, as the typical sample collection time is 5 minutes. Their low cost allows for numerous samples to be collected, but they are most commonly collected by inspectors which adds greatly to the cost.

  • Extremely accurate identification of a few mold species
  • Developed by the US EPA
  • Captures a “history” of mold – dead & alive
  • Identifies a very small number of mold species
  • Typically a “composite” of multiple sample areas or rooms

Environmental Relative Moldiness Index (ERMI) is a DNA based method of testing that will identify and quantify a very small number of mold species. ERMI testing was specifically meant to observe dust samples for analysis from large populations of homes or buildings to determine high-level observations of potential water damage. This method of testing lacks quantifiable sampling and can be viewed as highly variable. The representation of mold levels is intended to be more long-term rather than a snapshot of the current state of mold spores in the home. However, ERMI is a very small fishing net that misses many indoor air quality problems.

  • Less expensive than ERMI
  • Extremely accurate identification of a few mold species
  • Captures a “history” of mold – dead & alive
  • Identifies a very small number of mold species
  • Typically a “composite” of multiple sample areas or rooms

HERTSMI utilizes the same sampling methods as ERMI, but the panel only consists of 5 mold species. Some doctors utilize this sample as a way to determine if a home is safe for reentry after remediation has been completed. However, like ERMI, HERTSMI is a very small fishing net that misses many indoor air quality problems.