Indoor Environmental Quality: Dampness and Mold in Buildings
Dampness and Mold in Buildings
Dampness results from water incursion either from internal sources (e.g. leaking pipes) or external sources (e.g. rainwater). Dampness becomes a problem when various materials in buildings (e.g., rugs, walls, ceiling tiles) become wet for extended periods of time. Excessive moisture in the air (i.e., high relative humidity) that is not properly controlled with air conditioning can also lead to excessive dampness. Flooding causes dampness. Dampness is a problem in buildings because it provides the moisture that supports the growth of bacteria, fungi (i.e., mold), and insects.
In the presence of damp building materials the source of water incursion is often readily apparent (e.g., leaks in the roof or windows or a burst pipe). However, dampness problems can be less obvious when the affected materials and water source are hidden from view (e.g., wet insulation within a ceiling or wall; excessive moisture in the building foundation due to the slope of the surrounding land).
The health of those who live, attend school, or work in damp buildings has been a growing concern through the years due to a broad range of reported building-related symptoms and illnesses. Research has found that people who spend time in damp buildings are more likely to report health problems such as these:
- Respiratory symptoms (such as in nose, throat, lungs)
- Development or worsening of asthma
- Hypersensitivity pneumonitis (a rare lung disease caused by an immune system response to repeated inhalation of sensitizing substances such as bacteria, fungi, organic dusts, and chemicals)
- Respiratory infections
- Allergic rhinitis (often called “hay fever”)
Exposures in damp buildings are complex. They vary from building to building, and in different places within a building. Moisture allows indoor mold to multiply more easily on building materials or other surfaces, and people inside buildings may be exposed to microbes and their structural components, such as spores and fungal fragments. Mold may also produce substances that can cause or worsen health problems, and these substances vary depending on the mold species and on conditions related to the indoor environment. Moisture can also attract cockroaches, rodents, and dust mites. Moisture-damaged building materials can release volatile organic compounds that can cause health problems.
Researchers have not found exactly how much exposure to dampness-related substances it takes to cause health problems. Research studies report that finding and correcting sources of dampness is a more effective way to prevent health problems than counting indoor microbes. Therefore, NIOSH developed a tool to help assess areas of dampness in buildings to help prioritize remediation of problems areas.
The National Institute for Occupational Safety and Health (NIOSH) requests assistance in preventing respiratory symptoms and disease from working in or occupying damp office buildings, schools, and other nonindustrial buildings. This Alert describes the respiratory problems that occupants may experience from exposures in damp buildings, presents summary information on outbreaks of building-related respiratory disease, and provides recommendations on how to identify, respond to, and prevent building dampness and related respiratory symptoms and disease.
NIOSH Alert: Preventing Occupational Respiratory Disease from Exposures Caused by Dampness in Office Buildings, Schools, and Other Nonindustrial Buildings
DHHS (NIOSH) Publication No. 2013-102 (November 2012)