Mold type identified
Published 5:33 pm Sunday, September 27, 2015
WINTON – A sampling of the air quality on the second floor of the Hertford County Courthouse has confirmed the presence of mold, more specifically a type known as Aspergillus/Penicillium.
As reported in Thursday’s edition, county officials closed the entire second floor of the new courthouse earlier this week after noticing discoloration on the walls, particularly in Courtroom B and the Multi-Purpose Room. Courtroom A was also closed and sampled for mold.
The air samples, collected by Timothy Arn, owner of Home Spec of NC, Inc, were sent for testing purposes to Hayes Microbial Consulting, located in Midlothian, VA. The samples were taken in each of the three rooms, along with an outdoor control sample that Arn said would identify what type of mold may be proliferating. In addition, two swab samples were obtained of visible mold growth areas.
In his follow up letter, sent Sept. 24 along with the air quality report from the Virginia lab, Arn said, “We are basically dealing with just one species group of molds, Aspergillus/Penicillium. This is a common allergen group and is present in large amounts in room C (Multi-Purpose Room), lesser amounts in (Courtroom) B, and close to normal (when compared to the outdoor sample) in (Courtroom) A. The swab samples show the presence of the same species and are also related to rooms B and C. This group is one of the most common species found in the indoor environment.”
An online research database of mold species confirmed Arn’s findings – Aspergillus/Penicillium is the most common mold species to show up in indoor air samples. Most of the hundreds of sub-species are allergenic with only a few that are toxic. This group of species will grow with only the humidity in the air as its water source. The research also revealed that failures within an HVAC (heating and air conditioning) system can allow this mold to start growing on walls, furniture and clothing.
In the detailed report from Hayes Microbial Consulting, the Multi-Purpose Room tested the heaviest for Aspergillus/Penicillium (with higher spore counts on the left side of the room). Courtroom B tested for moderate levels of spores on the right side and heavy on the left. Tests conducted in Courtroom A revealed low to moderate levels on both sides.
The tests also indicated very light levels of Cladosporium and Curvularia spores, both considered as common allergenic mold.
There was no Stachybotrys or Memnoniella mold discovered. Those two typically grow together and both are considered the most common toxic mold species.
Arn’s letter supported what Hertford County Manager Loria Williams told the News-Herald in Thursday’s story that she felt the mechanical systems for the HVAC units controlling the air flow on the second floor were not designed or calibrated properly. She stated, “When that much cold air is blowing and if it’s not tempered correctly, then that leads to higher humidity levels, thus a higher chance that mold spores can develop.”
“The discussion conducted on site on Monday centered around the finding that the relative humidity (R/H) in the three rooms in question was very high,” Arn wrote in his report. “R/H readings were observed to range from 60% to as high as 70% in the three rooms. Typically the indoor environment is healthiest between 40% and 50% R/H. 60% to 70% is in the very high range and sets the environment as ‘ripe’ for fungal activity.”
Arn added that mold growth needs moisture for proliferation.
“A cure can only happen when the moisture causing conditions are remediated. The suspicion is that the HVAC system is not removing enough moisture for the load,” he said.
The good news in the remediation process is that Arn noted that the coming months typically note the lowest humidity levels of the year. He also provided county officials with an assessment and remediation of fungi in indoor environments and remediation and post remediation.
“The remediation process of this magnitude will need to be conducted by an experienced, trained, and licensed contractor rather than ‘in house’ staff,” Arn recommended. “Isolation of the three rooms in question, along with negative air pressure within the rooms, air scrubbers, and HEPA air filters, will all be necessary.”
Arn provided the county with the names of two companies that he said had been observed to accomplish successful remediation projects.
“Keep in mind that these companies specialize in clean-up; further discussion of correcting the moisture issues will need to be handled by the designer/specifier agency for this project,” Arn said.
The designer – Ware Bonsall Architecture of Charlotte – wrote in a Sept. 21 letter to county officials that upon learning of the possible issues of mold on the second floor, they had launched immediate measures and made adjustments to the HVAC system.
“(The adjustments) will yield immediate improvement in reducing the humidity within the courtrooms and the Multi-Purpose Room,” wrote Paul Bonsall in the letter, a copy of which was obtained by this newspaper.
Bonsall said it was discovered that the air conditioning systems were not performing as intended. He further stated that an outside air damper for the unit serving the Multi-Purpose Room was not fully closing when required.
As far as a specific reason to the high humidity levels in the three rooms, Bonsall wrote, “The building occupancy and daily usage is not as high as anticipated and the HVAC operation parameters and schedules were not set optimally for this condition, so they have adjusted fan operation and run schedules to perform better during periods of low usage.”
Bonsall said the next few weeks will be used to gauge the effectiveness of the recent adjustments and to make recommendations on how to further refine the system.
“We will propose other strategies to create a long-term solution that will involve implementing a more effective operational scheduling of the systems. The existing systems are capable of this type of scheduling, but require input from the county,” he said in the letter.
“Depending on the result of the changes made, we will propose a number of choices of strategies that can modify the mechanical system to reduce the likelihood and severity of a re-occurrence of these high humidity conditions within the building,” his letter concluded.
As noted in Thursday’s story, the first and third floors of the courthouse were not affected by the mold because they operate on different (and inclusive) HVAC systems.