Moisture in Buildings

For original article and more resources, please visit the CDC website

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.

Excess moisture is generally the cause of indoor mold growth. Molds reproduce by releasing tiny spores that float through the air until landing in other locations. When they settle on wet or moist surfaces, the spores can form new mold colonies. Moderate temperatures and available nutrient sources make most office buildings ideal for mold growth.

Recent media attention has increased public awareness and concern over exposure to molds in the workplace. While this may seem to be a new problem, exposure to molds has actually occurred throughout history. In fact, the types of molds found in office buildings are not rare or even unusual. It is important to understand that no indoor space is completely free from mold spores – not even a surgical operating room. Molds are everywhere, making our exposure to molds unavoidable, whether indoors or outdoors, at home or at work.

“Toxic Mold” & Stachybotyrs chartarum

Certain molds are toxigenic, meaning they can produce toxins (mycotoxins), but the molds themselves are not toxic, or poisonous. Hazards presented by molds that may produce mycotoxins should be considered the same as other common molds which can grow in your house or workplace. Contradicting research results exist regarding whether toxigenic mold found indoors causes unique or rare health conditions such as bleeding in the lungs. Research is ongoing in this area.

Mold growing in buildings, whether it is Stachybotrys chartarum (Stachybotrys atra) or another mold, indicates that there is a problem with water or moisture. This is the first problem that needs to be addressed.

Remediation of Dampness and Mold Contamination

First and foremost, determine the source of moisture and take appropriate measures to make repairs. Damp or wet building materials and furnishings as a result of leaks or flooding should be dried within 24 to 48 hours to prevent the growth of mold. Mold can be cleaned and removed from hard surfaces with commercial products, soap and water, or a bleach solution of no more than 1 cup of bleach in 1 gallon of water. Never mix bleach with ammonia or other household cleaners. Mold in or under carpets typically requires that the carpets be removed. Once mold starts to grow in insulation or wallboard, the only way to deal with the problem is removal and replacement. (CDC– Facts about Stachybotrys chartarum and Other Molds) For complete remediation guidelines go to the New York City Department of Health and Hygiene’s Guidelines on Assessment and Remediation of Fungi in Indoor Environments at

For “green” environmentally friendly cleaning solutions, go to Greenguard Environmental Institute at

I suspect mold in my workplace. How do I test for mold?

CDC does not recommend routine sampling for molds. Generally, it is not necessary to identify the species of mold growing in a building. Measurements of mold in air are not reliable or representative. If mold is seen or smelled, there is a potential health risk; therefore, no matter what type of mold is present, you should arrange for its removal. Furthermore, sampling for mold can be expensive, and standards for judging what is and what is not an acceptable or tolerable quantity of mold have not been established.

Symptoms related to dampness and mold

Health problems associated with excessive damp conditions and mold include:


Allergic responses like those to pollen or animal dander are the most common types of health problems related to mold. Typical symptoms include sneezing; irritation of the nose, mouth, or throat; nasal stuffiness and runny nose; and red, itchy or watery eyes. Inhaling or touching mold or mold spores can cause a person who was not previously allergic to mold to become allergic to mold. For people with known allergies, molds can trigger asthma symptoms such as shortness of breath, wheezing, or cough. Irritation can also occur in non-allergenic (non-sensitized) people. Additionally, scientific studies indicate that exposure to molds in the workplace can make pre-existing asthma worse. Recent NIOSH investigations document that some damp buildings are associated with developing new asthma.


Hypersensitivity pneumonitis (HP) is a kind of lung inflammation that occurs in persons who develop immune system sensitization (similar to an allergy) to inhaled organic dust. It can be mistaken for pneumonia, but it does not get better with antibiotics for infection.

Symptoms of HP can vary. Some persons have shortness of breath, cough, muscle aches, chills, fever, night sweats, and profound fatigue. These symptoms usually first appear 2 to 9 hours after exposure and last for 1 to 3 days. Other affected persons have progressive shortness of breath and cough, as well as weight loss. Work-relatedness may only become apparent over long holidays if symptoms resolve and then recur on return to work. With continued exposure, the persistent lung inflammation of both kinds of symptoms can lead to scarring and permanent damage. The slow progression of symptoms and the persistence of symptoms away from work may result in delayed recognition of work-related lung disease by both workers and physicians.

HP has been referred to as Bird breeder’s lung and Mushroom picker’s disease in specific occupations with a risk of HP from biological dusts. HP has been documented in workers in buildings with mold and bacteria contaminated air-conditioners (including spray-water cooling systems), and contaminated ductwork and filters. This lung disease has also occurred in workers who worked in water-damaged buildings with roof leaks, plumbing leaks, poorly draining condensation pans, and high indoor relative humidity.

HP is not contagious and is due to a person’s immune system reaction to inhaled microorganisms, whether dead or alive. It is possible for workers to have both dampness-related HP and asthma at the same time. Additionally, workplaces that have workers with HP may also have workers with building-related asthma.


Asthma is a form of lung disease in which the airways develop inflammation and bronchospasm (reversible narrowing) in response to sensitizing or irritating exposure. Affected individuals can experience episodes of shortness of breath, cough, chest tightness, and wheezing. These symptoms occur after exposure to nonspecific irritating substances in the air or after exposure to substances to which an individual is allergic. Medical testing typically reveals evidence of bronchial hyperresponsiveness such as an abnormal methacholine challenge test or reversible airways obstruction on spirometry (a test of lung function). It is important for affected individuals to have a comprehensive asthma treatment plan and regular follow-up with their physician. Early diagnosis and removal from the impacted damp office environment can cure asthma caused by workplace exposures.

In approximately 15% of asthmatics, the illness may have been caused, or made worse, by workplace exposures. Some occupational exposures are well known risks for asthma development (e.g., western red cedar; isocyanates). Indoor environment research has identified evidence of an association between damp buildings and asthma symptoms in individuals with pre-existing asthma. There is also new evidence of an association between damp buildings and new-onset asthma. In an individual with new-onset asthma or worsening of stable pre-existing asthma, measurements of lung function made several times a day at work and at home over several weeks may reveal a pattern of changing lung function that suggests a workplace cause.

For individuals with new-onset asthma or worsening of stable pre-existing asthma that is suspected to be related to the indoor environment, controlling or eliminating the sources of indoor contaminants, along with optimal medical treatment, may lead to symptoms of improvement or resolution.

What workers can do

When workers suspect their health problems are caused by exposure to building-related mold and dampness, workers should:

  • Report concerns immediately to supervisors or those persons responsible for building maintenance
  • See your doctor for proper diagnosis and treatment
  • Ask your doctor whether you should be medically restricted from the affected environment

What management and building owners can do

When health problems are believed to be caused by exposure to mold in the workplace, owners and managers should:

  • Advise workers to see their doctor for proper diagnosis and treatment
  • Evaluate the work area for evidence of mold and dampness
  • Repair leaks and remediate water damaged materials
  • Communicate with workers about areas of the building with evidence of mold or moisture damage and provide the status of remediation plans
  • Arrange for relocation of workers whose doctors restrict them from the implicated work environments


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