Background

The homeowner is a 64-year-old man who complains of chronic sinus and respiratory issues while in his home. The symptoms subside when he leaves the home for an extended period of time. His children, who are adult age and do not live with him, noticed that every time they visit they leave the home with a musty smell on their clothes. Concerned about the potential of an unusual mold condition within his home.


Initial Inspection & Testing

We performs a comprehensive assessment of the entire home. Mold contamination is detected in the basement, ambient living areas, and the attic. The basement is unfinished and the foundation walls and wood framing members are exposed. The contamination within the basement was observed on exposed ceiling sheathing, joists, and contents throughout the entire basement.


The HVAC unit is located in the basement area. It was replaced by the homeowner approximately 4 years prior to the inspection. However, its original and installed when the home was built about 30 years ago. Within the ambient living areas, mold was detected on most of the contents throughout the entire first-floor living area. Within the attic, mold contamination was detected on the attic roof decking and rafters.



This case study will demonstrate the following points:


1. Spore count concentration used in clearance does not necessarily mean the environment is cleaned of mycotoxins.


2. The presence of certain populations of mold spores is important to identify and is a relevant indicator of the potential presence of mycotoxins.


3. Low spore count concentrations, or what is perceived to be a comparable concentration to outside controls, does not mean the environment is clean of mycotoxins.


4. Due to the difficulty in reaching interstitial areas within the HVAC system and associated ducts and returns, it is improbable to thoroughly clean the HVAC system and associated ducts and returns once they have contaminated with mold and mycotoxins.

Due to the severity of the health issues with the homeowner, the population of molds detected in the HVAC system/associated ducts and returns, it was advised to remove the HVAC system and ductwork. However, the homeowner did not want to replace the system and had a cleaning of the system and ducts performed instead.


Post Remediation Verification Sampling of the HVAC system was declined by the client saying he felt because it was cleaned and should suffice. A month after everything was cleaned the homeowner was still experiencing adverse health issues while in the home. He felt more symptoms when the HVAC system was running. As a result, further testing was performed in the HVAC system.

Based on traditional accepted Post  Remediation Results, PRV air and results would be considered and suggest that the home was within a normal fungal ecology and or condition one state.  The HVAC system was not replaced as suggested.

However,  according to the homeowner, the HVAC system and associated ducts and returns were cleaned. Post Remediation Verification Sampling of the HVAC system was declined by the client saying he felt because it was cleaned and should suffice.

A month after everything was cleaned the homeowner was still experiencing adverse health issues while in the home.   He felt more symptoms when the HVAC system was running. As a result, In May of 2014 further testing was performed in the HVAC  system. A spore trap was placed in the main supply duct line to measure potential mold spore concentrations coming out of the system.      


Additionally,  both composite regular  Microscopy (swab sample)  and MsQPCR based on the ERMI panel of mold species were  collected from the HVAC filter, inside the main duct line, supplies, and returns;

It was suggested again to the homeowner to replace the HVAC system and associated ducts and returns. Nothing was done for several months, However, the homeowner decided to have the system cleaned again by a different company. This time the company employed removed the fiberglass insulation and removed the motor to clean and sanitize. The coils were not removed. The ducts and returns were cleaned again.



In December, the client was still experiencing adverse health issues after the system was cleaned. The client requested to sample in the Ambient living area – Family room and an EPA 36 surface and Mycotoxin samples within the HVAC system that was cleaned for the 2nd time.


After the system was cleaned twice.  The first time was a basic cleaning of the ducts and the second was a complete cleaning where the motor was removed and cleaned.   The coils were not removed. What is evident is that the second cleaning actually disturbed the spores harbored throughout the system and actually caused more distribution of both mold and mycotoxins through the duct system.  Below is what the Ductwork looks like after cleaning.


The results of the air sample detected elevated mold spore counts of Pencillium / Aspergillus.   Additionally a somewhat important indicated was the background debris was a 2 vs. 1 compared to outdoors.   Background debris is dirt and dust in the air. The results of the EPA 36 show several mold genera. Also, the Mycotoxin sample detected the Presence Of Trichothecenes. The results indicate that there is still mold contamination within the HVAC System and associated ducts and returns.  

Once the system was cleaned again, both an EPA  36 and Mycotoxin was collected from the HVAC system and associated ducts and returns. The  results of the EPA 36 and Mycotoxin were as follows:


The population of molds detected in the HVAC system- associated ducts and returns, with the EPA 36, it was advised to ensure the removal of all potential distribution sources the HVAC system and ductwork be replaced. The final EPA 36 and Mycotoxin still detected the presence of several mold general in the EPA 36. Stachybotrys was still detected. Additionally, mycotoxins were still detected in the system. Although lower concentrations, it is probable that both the spores and mycotoxins are still harboring within interstitial areas within the system that cannot be reached. It is improbable to thoroughly clean the HVAC system and associated ducts and returns once they have contaminated with mold and mycotoxins.



1. Spore count concentration used in clearance does not necessarily mean the environment is cleaned of mycotoxins.


2. The presence of certain populations of mold spores is important to identify and is a relevant indicator of the potential presence of mycotoxins.


3. Low spore count concentrations, or what is perceived to be a comparable concentration to outside controls, does not mean the environment is clean of mycotoxins.


4. Due to the difficulty in reaching interstitial areas within the HVAC system and associated ducts and returns, it is improbable to thoroughly clean the HVAC system and associated ducts and returns once they have contaminated with mold and mycotoxins.

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