Mold in the Workplace

Sources

Sources of water incursion are often apparent like leaks in the roof or a broken pipe. They are less obvious when affected materials and water sources are hidden. Wet insulation in a ceiling is an example.

Problems occur when materials in buildings become wet for extended periods of time. High relative humidity can also lead to excessive dampness. Moisture allows indoor mold to grow and multiply on building materials and surfaces. People inside damp buildings may be exposed to:

• Microbes
• Compounds released by microbes
• Structural components of microbes like spores and fungal fragments

Mold can produce substances that may cause or worsen health problems. These substances vary depending on the mold species and environmental conditions. Moisture can also attract cockroaches, rodents, and dust mites. Moisture-damaged building materials can release volatile organic compounds or irritating airborne chemicals.

Possible health effects

Research has found that people who spend time in damp buildings report health problems including respiratory symptoms and infections, developing or worsening asthma, hypersensitivity pneumonitis, allergic rhinitis or hay fever, and eczema (skin condition).

Allergies

Allergies or allergic responses to mold are common. In mold-allergic individuals, inhaling or touching mold may cause an allergic response, such as the following:

• Sneezing
• Nasal stuffiness or runny nose
• Red, itchy, or watery eyes
• Skin rash

Mold can also cause irritation of the eyes, nose, throat, skin, or lungs even in people who are not allergic to mold.

Asthma

Asthma is a lung disease that affects the airways in the lungs. Airways can become inflamed and narrowed at times. This makes it harder for air to flow out of the lungs when breathing out.

People with asthma may have one or more of the following symptoms:

• Coughing
• Wheezing
• Chest tightness
• Shortness of breath

Asthma is associated with exposure to irritants, allergens, and physical conditions (e.g., cold air) called triggers. Many asthma triggers can be in the workplace. Research shows evidence of an association between damp indoor spaces and asthma symptoms in individuals with pre-existing asthma.

This means exposure to molds in workplaces can make pre-existing asthma worse. There is also evidence of an association between damp indoor spaces and new-onset asthma.

Symptoms of work-related asthma tend to get better when away from work. However, in some cases, symptoms do not improve until an extended time away from the exposure or trigger. Workers who are already sensitized to mold may even respond to a trace amount of mold.

Diagnosing work-related asthma

Diagnosing asthma is based on a combination of medical and exposure history, physician examination, and medical tests such as pulmonary function tests (e.g., spirometry and bronchodilator responsiveness testing).

Workers may be able to use peak flow meters to link changes in lung function with environmental settings. This is done by frequently measuring lung function multiple times a day at home and at work over several weeks. Recording these measurements may reveal a pattern of changing lung function and possible work relatedness.

Asthma takes ongoing monitoring and management to keep it under control. It is important for affected individuals to have a comprehensive asthma treatment plan and regular follow-up with their healthcare providers.

Hypersensitivity pneumonitis

Hypersensitivity pneumonitis is an immune system disorder. It causes the lungs to become inflamed in reaction to certain substances like inhaled bacteria, fungi, plant and animal proteins, or chemicals.

It can seem like the flu or pneumonia, but hypersensitivity pneumonitis does not get better with antibiotics for infection.

Symptoms of this illness can vary. Some persons experience:

• Shortness of breath
• Cough
• Muscle aches
• Chills
• Fever
• Night sweats
• Extreme fatigue
• Weight loss

Symptoms may improve after a few hours or days when away from the substance or allergen causing illness. Likewise, hypersensitivity pneumonitis may be work-related if a worker's symptoms and medical tests (e.g., pulmonary function tests) improve when away from work and worsen when returning to work. With continued exposure, persistent lung inflammation over time could lead to permanent lung damage.

Hypersensitivity pneumonitis has been documented with workers in buildings with contaminated air-conditioners, ductwork, and filters. It has also occurred in workers in water-damaged buildings with roof leaks, plumbing leaks, or high indoor relative humidity.

Resources

Dampness and Mold Assessment Tool

Researchers do not know how much exposure to dampness-related substances it takes to cause health problems. Finding and promptly correcting sources of dampness is more effective at preventing health problems than air samples for indoor mold. NIOSH developed a tool to help assess areas of dampness and prioritize remediation of problem areas in buildings.

Dampness and Mold Assessment Tool - General Buildings

Explains how to use the Dampness and Mold Assessment Tool - General Buildings.

July 2, 2024

Dampness and Mold Assessment Tool - School Buildings

Explains how to use the Dampness and Mold Assessment Tool - School Buildings.

July 2, 2024

NIOSH Alert: Preventing Occupational Respiratory Disease from Exposures Caused by Dampness in Office Buildings, Schools, and Other Nonindustrial Buildings

Explains how to prevent work-related breathing diseases from dampness in buildings.

June 6, 2014

Mold Health Hazard Evaluations

The NIOSH Health Hazard Evaluation (HHE) program is a service that evaluates U.S. workplaces for health hazards. NIOSH has performed many evaluations related to mold concerns in buildings. To learn more about these evaluations, go to the Search HHE Reports page:

1. Type "mold" in the search box.
2. Click the Search button for a list of mold-related HHE reports.