A new Health Hazard Evaluation (HHE) from the National Institute for Occupational Safety and Health (NIOSH) paints a detailed picture of how indoor dampness, mold growth, and ventilation system failures can compound over time—creating conditions that undermine building performance and affect occupant health. Although the investigation focused on a college campus, many of the documented issues echo the challenges that laboratories face when humidity control falters, HVAC systems age, or leaks go unaddressed.
The report summarizes more than a decade of indoor environmental quality concerns, ranging from persistent water intrusion and elevated humidity to visible mold and malfunctioning ventilation equipment. Employees across the campus reported symptoms affecting multiple body systems, and NIOSH’s two-visit assessment confirmed extensive moisture problems, inadequate air handling, and inconsistent communication between facilities teams and building occupants.
Key findings on moisture, humidity, and mold
NIOSH’s review found that high indoor humidity was a recurring condition across multiple buildings. Inspectors documented:
- Condensation leaking from supply vents, ductwork, and chilled-water pipes
- Indoor air above the dew point, enabling moisture accumulation
- Widespread mold and moisture damage in ceilings, crawl spaces, and living areas
- Musty odors and water-stained building materials in numerous locations
Humidity during walkthroughs often ranged from 55 percent to 75 percent—well above the recommended 30 to 50 percent range. Buildings also lacked vapor barriers in crawl spaces, allowing ground moisture to infiltrate interior spaces. Air sampling reports from previous years showed elevated indoor levels of molds such as Aspergillus/Penicillium, Cladosporium, and Stachybotrys, including instances where indoor concentrations exceeded outdoor levels, signaling indoor sources.
Ventilation system failures and maintenance gaps
Ventilation issues were central to the environmental problems identified. NIOSH noted multiple HVAC units that were inoperable, poorly maintained, or operating without the required outdoor air intake. In several buildings, energy recovery ventilators were out of service for extended periods, leaving spaces without adequate fresh air.
In some areas, supply systems could not meet outdoor air requirements, while exhaust systems created negative pressure that drew humid air into occupied spaces. Condensation from cooling coils and ductwork repeatedly damaged ceiling tiles and interior finishes. NIOSH emphasized the need to maintain ventilation equipment according to ASHRAE Standard 62.1-2022, insulate ductwork and piping to limit condensation, and maintain indoor dew point below 60 degrees Fahrenheit in mechanically cooled environments.
Recommendations for moisture control and remediation
To address the underlying moisture drivers, NIOSH recommended:
- Installing vapor barriers in crawl spaces and remediating groundwater intrusion
- Improving drainage, cleaning gutters, and extending downspouts
- Properly insulating ductwork and controlling indoor humidity
- Maintaining HVAC systems, filters, coils, drip pans, and dampers per manufacturer guidelines
- Removing mold-damaged materials using appropriate containment practices
- Implementing a dampness and mold assessment tool for routine inspections
The agency also highlighted the need for better communication systems—such as anonymous reporting options, clear updates on work orders, and an indoor environmental quality team—to ensure issues are addressed promptly and transparently.
Implications for laboratory operations
For laboratory leaders, the HHE serves as a cautionary example of how moisture and ventilation issues can escalate when early signs go unaddressed. Laboratory work depends on stable humidity, reliable outdoor air supply, and well-maintained HVAC systems not only for comfort but also for instrument accuracy, sample integrity, and biosafety.
The report underscores several practices essential for lab managers:
- Conducting routine inspections for leaks and hidden mold reservoirs
- Verifying that systems supplying lab spaces meet ASHRAE outdoor air requirements
- Monitoring humidity trends, especially during seasonal transitions
- Ensuring timely remediation of condensation and moisture damage
- Collaborating with facilities teams through structured reporting processes
NIOSH’s evaluation shows how environmental concerns develop long before they become visible, and labs are particularly sensitive to those early shifts. Uncontrolled humidity or inconsistent airflow can disrupt research conditions just as readily as a malfunctioning instrument. By building strong reporting channels and keeping moisture and ventilation on their regular inspection list, lab managers can stay ahead of problems that erode safety and reliability.
This article was created with the assistance of Generative AI and has undergone editorial review before publishing.
