Mold Testing and Bacteria Testing

Trusted Laboratories

Trusted Laboratories

Phone: (905)290-9101
Toll Free: 1-866-813-0648

Worried About Mold?

Click ** Get Your Free Assessment Now!**

  • Home
  • About Us
  • Services
    • Mold Testing
    • Bacteria Testing
    • Legionella Testing
    • Cannabis Testing
    • Antimicrobial effectiveness testing
    • Biological Indicators and Sterilization Process
    • Contract Microbiological Research
    • Environmental Monitoring & Bioburden Testing
    • Material Fungus Resistance Testing
    • Materials Standard Testing
    • Cannabis Licence
  • Accreditation
  • Mold Test Kits
  • View Courses
  • Freebies
    • Live Presentations
    • FREE Mold Inspection Quiz
    • FREE Mold Spore Identification Quiz
  • Resources
    • Chain of Custody Form
    • Ask a Question
    • How to Take Samples
    • Results Interpretation
    • Mold and Bacteria Pictures
    • Jobs
  • Contact us
You are here: Home / Results Interpretation / Understanding Spore Trap Results and Analyses

Understanding Spore Trap Results and Analyses

Dr Jackson Kung'u

To understand spore trap results one has to understand how labs analyze the samples. When enumerating airborne fungal spores, most labs, for practical reasons, analyze a percentage of the sample trace (often 15-25%) instead of 100%. A few labs claim that they analyze 100% of the sample trace. Obviously analyzing 100% of the sample trace sounds better than analyzing say 15 or 25%. In fact, some people argue that analyzing less than 100% of the sample trace is incorrect, inaccurate and gives skewed results. However, it is important to note that the accuracy of spore traps is affected by so many factors such that the contribution to inaccuracy/accuracy by the percentage of the sample trace analyzed in the lab is highly likely insignificant if at least 15% of the sample is analyzed. Even if 100% of the sample trace is analyzed, the results of spore traps would still be skewed in one way or another. Perhaps the most important of these factors is the sample volume collected. The volume of air collected for analysis is in most cases 75L or 150L. However, the final spore count is reported as the number of spores per cubic meter of air. That means ideally we should collect and analyze 1000L of air because by collecting 75 or 150L of air, the samples are only 7.5% and 15% respectively of what should have been analyzed. Unfortunately the spore traps (Air-O-Cell, Allergenco, etc.,) are not designed to collect large volumes of air especially in a dusty environment. In a dusty environment spore traps get overloaded with dust making it difficult for the analyst to see the spores.

The other factor that skews spore trap results is the fact that fungal spores are not uniformly distributed in the air.  That means if the spores are not uniformly distributed in the air, even the position and the height at which we place the sampler would skew the results.

Another factor that skew results is the fact that the spore concentration in a building varies not only with the season but also with the day and time of the day. In one study it was found that the spores of Aspergillus fumigatus can increase temporary to a significantly high concentration and then decline to “normal” level within 30 min only. This means the 5 or 10 minutes samples that are collected using spore traps are only a measure of spore concentrations at the time of sampling.

Spore trap- notice the non-unform distribution of Asp/Pen spores
AspPen notice the non uniform distribution of spores

Does Analyzing 25% of Spore Trap Sample Trace Make Spore Trap Results Incorrect and Inaccurate?

The simple answer to this question is NO. First, spore traps are not meant to determine the actual spore count in the air. They are meant to give an idea of the types of spores present in the air and the concentrations of these spores relative to each other. Analyzing spore traps by direct microscopy is a complex process and there are limitations. Depending on the experience of the analyst there are counting and identification errors. Because of eye fatigue, counting errors are likely to be higher for a sample trace analyzed at 100% than one analyzed at 25%.

At MBL we use the ASTM Standard “Standard Test Method for Categorization and Quantification of Airborne Fungal Structures in an Inertial Impaction Sample by Optical Microscopy (Designation: D 7391 – 17 e1)“. This is the only standard currently available for spore trap analysis. The standard does not specify the minimum percentage of the sample trace to count and for good reasons. Practically, not every sample can be analyzed at 100%. The density of particulates (spores and other particulates) on the sample trace and the size of particulates determine how easy and fast the sample can be analyzed. Analyzing 100% of a highly loaded sample is not only difficult but could take one to several hours and will have little or no added value to the results because counting errors will be made during the analysis.

When Is It Possible to Analyze 100% of Sample Trace

The only time it is practically possible to analyze 100% of sample trace is when you have relatively few scattered spores and other particulates on the slide. With heavily loaded samples it’s very difficult for the analyst to keep track of what they have and haven’t counted under the microscope. As mentioned earlier, the analyst is likely to be fatigued and count many spores twice or miss counting some of them altogether. Compare the 2 images below which are showing spores and other particulates in just a single field of view of a microscope. Again, even for samples with low particle density, does analyzing 100% of sample trace add any value to the results? We would like to hear from you…

Spore trap- mixture of spores
Heavily loaded sample with tiny spores Difficult to count 100
Spore trap- Pithomyces spores
Big scattered spores Easy to count 100

Fungal Spore Identification Course

Master fungal spore identification by taking the Fungal Spore Identification Course! Upon completion participants will have the necessary skills to sample for airborne fungal spores, analysis samples, accurately count and identify a variety of spore types, and calculate airborne spore. concentrations.

author avatar
Dr Jackson Kung'u
Dr. Jackson Kung’u is a Microbiologist who has specialized in the field of mycology (the study of moulds and yeasts). He is a member of the Mycological Society of America. He graduated from the University of Kent at Canterbury, UK, with a Masters degree in Fungal Technology and a PhD in Microbiology. He has published several research papers in international scientific journals. Jackson has analyzed thousands of mould samples from across Canada. He also regularly teaches a course on how to recognize mould, perform effective sampling and interpret laboratory results. Jackson provides how-to advice on mould and bacteria issues. Get more information about indoor mould and bacteria at www.drjacksonkungu.com.
See Full Bio
social network icon social network icon

No related posts.

Filed Under: Results Interpretation

How Much Do You Know About Mold?

Take a 3 minutes Quiz and find out how much you know about mold. To start the Quiz please Click START QUIZ below.

General Knowledge Mold Quiz

General knowledge mold quiz- Try it, it's fun!
Complete the form below to see results
Share your result via
Facebook X Pinterest LinkedIn Email

By the way, we have online mold courses at https://www.mytrainingcourses.ca

« Mould contamination in schools and health effects on children
How to improve spore trap analysis results »

Online Training

Learn To Analyze Airborne Fungal
Spores And Become A Spore Analyst!

Mold Testing Kits

Use mold test kit to detect black
molds that may be in your home!

Bacteria Testing

Microbiology Testing lab providing Testing of E. coli, Total Coliforms & Fecal!

Legionella Testing

‪Laboratory testing for Legionella by culture with an identification!

Laboratory Mold Testing

‪Call MBL for specialized analyses and Identification of mold, yeast and bacteria!

Mold Inspection Services

As Mold Inspection Specialists, We
Are Who To Call For Mold Inspection!

Recent Posts

Is E. coli Airborne? Separating Facts from Myths in Bacterial Sampling

In the world of indoor environmental quality, bacterial contamination often raises questions, especially when dealing with sewage damage. A recent … [Read More...]

 - Mold Testing and Bacteria Testing

Is “Black Mold” Equivalent to “Toxic Mold”?

Is "Black Mold" Equivalent to "Toxic Mold"? No, black mold is not equivalent to toxic mold. "Black Mold" is a term that is often used incorrectly to … [Read More...]

 - Mold Testing and Bacteria Testing

Exploring Non-Tuberculous Mycobacteria (NTM): Understanding Characteristics and Implications

What Are Non-tuberculous Mycobacteria (NTM)? Non-tuberculous Mycobacteria are mycobacteria other than Mycobacterium tuberculosis and M. leprae, and … [Read More...]

Learn With Us…

Courses

  • Mold Inspection, Identification and Control
  • Fungal Spore Identification
  • Mold Inspection Business Course
  • How to take Mold Samples Course
  • Coliform Testing
  • WHMIS
  • INTERESTING KNOWLEDGE QUIZES

Get In Touch

By phone or by email
905-290-9101
Email

Our Location
1020 Brevik Place, Unit 1A • Mississauga, ON L4W 4N7
(Phone: 905-290-9101 • toll-free: 1-866-813-0648 • fax: 905-290-0499.)

  • Email
  • Facebook
  • LinkedIn
  • Twitter
  • YouTube

Search this Site

Recent Posts

  • Is E. coli Airborne? Separating Facts from Myths in Bacterial Sampling
  • Is “Black Mold” Equivalent to “Toxic Mold”?
  • Exploring Non-Tuberculous Mycobacteria (NTM): Understanding Characteristics and Implications

Useful Links

  • Chain of Custody Download
  • Contact us
  • Privacy policy

Copyright © 2025 · Mold & Bacteria Consulting Laboratories. Log in