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The most common mold types include Alternaria, Aspergillus, Cladosporium, Fusarium, Penicillium, Rhizopus, and Stachybotrys. These fungi produce microscopic spores that burst and spread easily through the air, settle on surfaces, and — if conditions are right — grow into thriving colonies. Mold can range in color from white to green, orange, brown, and black.

Health Effects of Mold

Mold exposure occurs both indoors and outdoors. Some people are more sensitive than others, especially those with allergies and asthma. Exposure may cause cold-like symptoms, watery eyes, sore throat, wheezing, and dizziness, and can trigger asthma attacks. Those most severely affected include:

• Infants and children
• Elderly individuals
• People with respiratory conditions, allergies, or asthma
• Persons with weakened immune systems (HIV, chemotherapy patients, organ transplant recipients)

Detection

Mold is typically identified through a musty odor and discoloration of surfaces. All molds should be treated the same and regarded as potential health risks — it is usually not necessary to determine the specific type of mold before taking action.

Common Causes of Mold Growth

• Flooding or standing water
• Condensation on windows or walls caused by high indoor humidity
• Poor ventilation in attics and closets
• Overflow from tubs, sinks, or toilets
• Leaky basement or dripping pipes
• Roofs in need of repair or faulty gutters
• Inadequate venting of kitchen and bath humidity

Prevention

• Clean and dry surfaces — mold will grow on damp surfaces within a couple of days at normal temperatures
• Run exhaust fans during and after showers
• Fix plumbing leaks promptly
• Control humidity below 40 percent — use dehumidifiers and air conditioners when levels are high
• Increase air circulation; move furniture away from walls and open closet doors
• Prevent condensation by insulating walls and installing storm or thermal-pane windows

Cleanup and Removal

Dead mold still poses health risks and must be removed — killing it with bleach does not eliminate the health risk. When cleaning in a moldy environment:

• Use a HEPA filter or N95 rated mask (two straps) and gloves
• Porous materials (drywall, carpet pads) should be discarded; hard plastic, glass, and metal can be cleaned
• Disinfect structural members with a solution of 1 cup chlorine bleach per 1 gallon of water — keep the surface wet for 10–15 minutes to kill mold, then allow to dry naturally over 6–8 hours in a well-ventilated area
• Never mix bleach and ammonia
• Remember: chlorine bleach deactivates termite treatments — reapply after cleanup in termite-prone areas

Drying Out Before Rebuilding

Wood must have a moisture content of less than 15 percent before drywall or other coverings are applied. Drying methods include ventilation (usually most effective — can remove several gallons of water per day), heat application, and dehumidifiers. A residential dehumidifier running at 80°F and 60% relative humidity will remove 1–2 pints of water per hour.