Moisture is the most common cause of mold growth. Molds are pervasive in both indoor and outdoor environments. Active mold growth and odors indicate that too much moisture is present. Indoor mold growth occurs when spores land on wet materials that can be a food source for mold. Mold growth indoors points to the presence of a water source. Water can come from plumbing, roofs, floods, condensation, or entry via the building exterior. Mold and fungal growth may also happen when indoor relative humidity is more than 70 percent for a few days.
What are ways to prevent mold growth?
The best way to prevent mold growth is to prevent or control water that is entering and exiting a building. Controlling moisture and preventing mold growth avoids damage to building materials. It also prevents mold exposures that can lead to allergic reactions or trigger asthma symptoms.
Methods for controlling water in a building include:
- Lower humidity with dehumidifiers and use exhaust ventilation in bathrooms, shower, and cooking areas
- Prevent condensation with adequate indoor insulation and ventilation
- Periodically check the building for signs of water or mold growth
- Respond promptly to reports of leaks
When water damage is discovered, it is important to examine the materials that are wet. Some materials, such as hard plastics, brick, and metals, do not support mold growth. These materials can be cleaned with water and detergent. Absorbent, carbon-containing materials like ceiling tiles, manufactured wood, gypsum wallboard materials, and carpets can serve as a food source for mold growth. These materials should be replaced if not dried between 24 to 48 hours after water damage.
The DPH Indoor Air Quality Outreach and Education Unit developed guidance for removal and prevention of mold growth in schools and public buildings.
Indoor air quality and moisture in public buildings
DPH Indoor Air Quality Outreach and Education Unit staff conduct assessments that examine both the interior and exterior of a building. They look for sources of water and identify any signs of water damage. Commonly observed signs of water damage in schools and large buildings include:
- Stained ceiling tiles
- Damage to cabinets and countertops in sink areas
- Spills on carpets
Staff may also take moisture measurements. However, mold testing is not conducted or recommended in any building, regardless of type. This is because there are no standards or limits for comparison.
Related links
Additional resources
Massachusetts
DPH Remediation and prevention of mold growth and water damage in public schools and buildings: Information on removal and prevention of mold growth to maintain air quality
National
- EPA Mold: Guidance and resources about mold and moisture for homes, schools, multifamily and commercial buildings
- EPA Resources for flood cleanup and indoor air quality: How to clean up and protect indoor air quality after flooding occurs in a home