Report on Mold Concerns in Keene State Dorms, Fall 2021

Written by Ralph Stuart, CIH, CCHO
Originally written: November 29, 2021
Updated: December 1, 2021
An updated report with the results of the sampling described below can be found here.
Questions about the information below can be directed to


In the fall of 2021, concern about health symptom clusters in Keene State dorms led to questions about potential mold contamination in the spaces of concern. It is interesting to note that similar concerns have arisen at all three USNH campuses this fall, as well as on campuses nationally.

At Keene State, two dorms are the center of this concern, Pondside 3 and One Butler Court. These dorms were both built in 2006 with air conditioned ventilation systems of similar design and components.

Inspection of the areas of concern by Ralph Stuart identified areas of dirt and mold accumulation that were limited to areas in and near the diffusers of the ventilation systems. In order to reduce the amount of ambient dust in the Pondside 3 207 suite, Ralph provided 5 HEPA air cleaners to the suite occupants.

In order to determine if molds with potential health concerns are present in these locations, Keene State has hired an industrial hygienist to conduct sampling in the two affected dorms. This “spore trap” sampling took place on Wednesday, December 1. Results will be available about a week after sampling occurs.

In the meantime, the Keene State custodial services contractor cleaned all of the ventilation system diffusers in the suites in One Butler Court and Pondside 3 between November 21 and December 1.

As of December 1, Ralph is continuing to receive reports of concerns in specific suites in these two buildings and will follow up with visits to inspect the current situation with the occupants. Anyone with these concerns can contact him at the e-mail address above to set a time for this visit.

Pondside 3 Observations

In room ventilation components

Building wide system components

Ongoing Air Monitoring

To further assess whether there are likely conditions for growing mold in these dorms, air quality monitoring is being conducted in the 207 Pondside 3 suite. According to the EPA, the primary parameter of interest for assessing mold potential is relative humidity. This value should be kept below 60%. Monitoring between November 18 and November 29 indicates that this suite met this criteria.

We additionally monitored CO2 and fine particle levels in the suite and they are at similar levels as those found in KSC classrooms.

Working Hypothesis

The most likely reason for the increased presence of mold in these two dorms is the moist summer this year. When outdoor air enters these buildings through open windows, it carries humidity and dust. When the air conditioning system is on, cool air going through the diffusers condenses water vapor, which can collect dust on the diffusers. Moist dust is a favorable location for the growth of many mold species. These molds are noticeable by the discoloration on locations they grow. Similar growths were noticed and cleaned this summer on soft surfaces in other KSC dorms.

According to the Environmental Protection Agency and Centers for Disease Control, it is unlikely that airborne amounts of mold are present in locations without visible growth.

Frequently Asked Questions

  • Should we sample for radon as well?
    • As explained on the EPA web page at radon is a radioactive gas associated with an increased risk of lung cancer but is not associated with respiratory illnesses.
  • What chemical is being used to clean the diffusers?
    • The custodial contractor uses a water solution of Oxivar, a solution of hydrogen peroxide and benzyl alcohol to disinfect the diffusers. The SDS for Oxivar can be found here.
  • What kind of mold testing will be conducted?
    • Between 10 and 15 samples for airborne dust will be collected in the two dorms of concern in spore traps and examined to determine what species of mold is found in them. This sampling will be done by Desmarais Environmental, Inc.
    • The mold of greatest concern is  Stachybotrys chartarum, which is suspected of having general health effects; if this mold species is found, further testing will be required to identify its source.
    • Other molds that are considered irritant molds may be found. If medical review of these results indicate that these molds are likely to be associated with the concerns being reported, further testing can be arranged.


EPA Guidance on Managing Mold:

CDC Basic Facts about Mold and Dampness:

NIOSH Dampness and Mold Assessment Tool