NIOSH 2013-102: Preventing Occupational Respiratory Disease from Dampness in Office Buildings, Schools, and Other Nonindustrial Buildings

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Overview

This NIOSH Alert addresses the significant public health problem of dampness-related respiratory disease in non-industrial indoor environments including office buildings, schools, and other public buildings. It provides evidence-based recommendations for building owners, employers, and occupants.

The Problem: Dampness and Respiratory Disease

Key Finding

Workers and occupants in damp buildings have a significantly increased risk of developing respiratory symptoms, asthma, and other respiratory diseases. Research shows:

• Dampness and mold in buildings are associated with upper and lower respiratory tract symptoms
• Occupants of damp buildings experience 30–50% higher rates of respiratory illness
• Asthma is significantly more prevalent among workers in damp buildings
• Hypersensitivity pneumonitis (HP) and other serious respiratory conditions can result from workplace dampness exposures

What Causes the Problem

Dampness in buildings creates conditions for:

• Mold growth — hundreds of species of fungi can grow on wet building materials
• Bacterial growth — including Legionella and other respiratory pathogens
• Dust mite proliferation — thrives in humid conditions (>50% RH)
• Chemical emissions — dampness causes building materials to off-gas volatile organic compounds (VOCs) and breakdown products
• Endotoxins — from gram-negative bacteria associated with dampness

The specific causative agents are often not identified — the presence of dampness itself is the risk factor, regardless of which specific organisms are present.

Who Is at Risk

Higher-risk populations in damp buildings:

• Workers who spend significant time in affected buildings
• Individuals with pre-existing asthma or allergies
• Immunocompromised individuals
• Children in schools (more hours of exposure, developing respiratory systems)
• Elderly occupants

Recommendations for Building Owners and Employers

Prevent Dampness

1. Inspect buildings regularly for signs of water damage, leaks, and condensation
2. Respond promptly to all water intrusion events — dry affected areas within 24–48 hours
3. Maintain HVAC systems to prevent moisture accumulation in ducts and drip pans
4. Control indoor relative humidity — maintain between 30–60%; ideally 40–50%
5. Ensure adequate ventilation as specified by ASHRAE Standard 62.1
6. Design and construct buildings to minimize moisture intrusion

Investigate and Remediate

1. Investigate all complaints of odors, visible mold, or moisture-related symptoms from occupants
2. Conduct thorough building assessments when dampness is suspected — visual inspection, moisture measurements
3. Remediate identified dampness problems promptly and thoroughly
4. Follow established remediation guidelines (EPA, IICRC S520) for mold removal
5. Verify remediation success with post-remediation assessment

Protect Workers During Remediation

1. Provide appropriate PPE to remediation workers
2. Implement containment to prevent cross-contamination during remediation
3. Follow OSHA standards for worker protection

Recommendations for Indoor Environmental Quality (IEQ) Teams

When investigating potential dampness problems:

1. Conduct systematic walkthrough of the building, noting:

• Visible moisture, stains, or mold
• Musty odors
• Evidence of past water damage
• HVAC system condition

1. Review building history:

• Past water intrusion events
• Maintenance records
• Previous occupant complaints

1. Measure relative humidity throughout the building
2. Assess the HVAC system:

• Inspect cooling coils, drain pans, and ductwork
• Check for adequate outdoor air delivery
• Verify proper operation

1. Communicate findings to building management with specific remediation recommendations

Recommendations for Building Occupants

If you work or spend time in a building you suspect has dampness problems:

1. Report symptoms and concerns to your employer, building manager, or school administrator
2. Document symptoms — note when they occur and whether they improve when you leave the building
3. Seek medical evaluation if you develop respiratory symptoms
4. Request a building investigation if symptoms are widespread among occupants

Health Effects Associated with Dampness

Respiratory Conditions

Other Health Effects

• Eye and skin irritation
• Fatigue and cognitive symptoms (in severe cases)
• Exacerbation of existing conditions

Recognizing a Dampness Problem

Visual indicators:

• Visible mold or mildew on surfaces
• Water stains on walls, ceilings, or floors
• Efflorescence (white mineral deposits) on masonry
• Peeling paint or wallpaper
• Warped or buckled flooring

Sensory indicators:

• Musty or earthy odors
• Persistent dampness in air

Building performance indicators:

• History of flooding or water intrusion
• HVAC system problems
• Poor vapor barriers or inadequate building envelope

Key Principles for Prevention

1. Water intrusion must be stopped — no amount of cleaning will solve a recurring dampness problem without addressing the source
2. Speed matters — materials dried within 24–48 hours rarely develop significant mold growth
3. Porous materials cannot be cleaned — wet drywall, insulation, and ceiling tiles should be replaced
4. HVAC systems require attention — cooling systems that allow moisture accumulation are a major source of indoor dampness
5. Occupant communication is essential — building occupants often notice problems before formal inspections

Additional Resources

• NIOSH: www.cdc.gov/niosh
• EPA Mold Resources: www.epa.gov/mold
• ASHRAE Standard 62.1 (Ventilation for Acceptable Indoor Air Quality)
• ASHRAE Standard 55 (Thermal Environmental Conditions for Human Occupancy)
• IICRC S520 Standard for Professional Mold Remediation