WestCon Tribune

IDENTIFYING AND MITIGATING MOLD CONTAMINATION IN BUILDINGS
PRESENTED BY FRANCIS (BUD) OFFERMANN, PRESIDENT, INDOOR ENVIRONMENTAL ENGINEERING

New Westcon member Bud Offermann, President of Indoor Environmental Engineering, gave an excellent presentation. The meeting was filled with interesting and valuable information and became very interactive with questions and participation from the large group of members and guests.

The following information was in a handout distributed by Mr. Offermann:
Modern building envelope assemblies can reduce the natural air exchange rate between indoors and outdoors to such an extent , that problems involving control of indoor air contaminants have now evolved (e.g. Sick Building Syndrome, SBS). Another problem resulting from the design of building envelope sections to minimize heat and air transfer, perhaps even more important than the reduction of infiltration, is control of moisture in the building and in the building envelope cavities.

Excessive moisture in buildings leads to:
• Fungal growth which causes building materials to prematurely degrade and causes building occupants to get sick
• Metal corrosion
• Paints and surface coatings to separate
• Concrete and masonry efflorescence
• Movement of building elements

The critical factor governing fungal growth in building is moisture.

For fungal growth to develop in buildings, surfaces of materials must become wet and stay wet for prolonged periods of time (i.e. days, weeks).

Building materials can become wet if the building envelope does not preclude liquid or capillary flow of water (rain or landscape irrigation), or if the surface temperature of the building materials falls below the dew point and condensation occurs.

With respect to condensation of water vapor, the relationship between air temperature, relative humidity, absolute humidity (humidity ratio), and dew point are summarized in the ASHRAE psychometric chart.

If a surface temperature falls below the dew point temperature then condensation of moisture will occur on that surface (e.g. surface temperatures lower than 51 OF in air that is 50% relative humidity @70 OF).

What are fungi and molds? Fungi are a class of organisms that are not plants (because they lack chlorophyll) and not animals (because they have no organs for food uptake).

Fungi may be divided into three groups:
• Yeasts
• Fleshy fungi or macro fungi (mushrooms)
• Filamentous fungi or micro fungi (molds)

The filamentous fungi, or molds, are of particular concern in buildings with chronic moisture problems since they produce spores which readily become airborne and can be inhaled.

Many types of fungal spores contain toxic and allergenic compounds which can cause irritation or disease to those exposed. Exposure to the toxic compounds produced by fungi may be by skin contact (rash and lesions) or by inhaling the airborne spores (allergies, asthma, respiratory disease). Breathing air contaminated with fungal spores can lead to significant health problems for some individuals. Health effects range from aggravated allergy symptoms and asthma attacks to respiratory infection and systemic toxicoses. Some people are more susceptible to developing serous health effects from exposure to fungal contamination such as infants and elderly people and those individuals undergoing chemotherapy, organ and bone marrow transplantation, or those with HIV/AIDS.

Moisture problems and resulting fungal growth can occur:
• On indoor surfaces (e.g. walls, ceilings, floors)
• On concealed surfaces (e.g. inside of wall, ceiling, and floor cavities).
On indoor surfaces, moisture problems and fungal growth are the result of:
• Flow of rain water through the envelope into building envelope cavities and absorption by interior surface materials
• Condensation of moisture onto indoor surfaces which are below the dew point temperature
• Excessive indoor sources of moisture
• Too little ventilation
• Indoor surface too cold
On concealed surfaces, moisture problems and fungal growth are the result of:
• Flow of rain water through the envelope into building envelope cavities and wetting of interior cavity surfaces.
• Condensation of moisture onto cavity surfaces which are below the dew point temperature
• Excessive transport of moisture into cavities
• Cavity surfaces too cold

Assessment of the fungal contamination in a building generally involves a visual survey of the extent of the contamination on visible indoor surfaces as well as on concealed surfaces.
Inexpensive tape lift samples can be collected and analyzed by microscopy to provide the forensic evidence needed to conclude whether the visually assessed contamination is fungal growth or just staining.

Air samples can provide the forensic evidence upon which opinions regarding the personal injury aspects of a fungal contamination case may be based. Air samples can also be used to forensically prove that there is a source of fungus in the building. Samples are collected form indoor and out door locations and the concentrations compared. In buildings without indoor sources of fungal contamination the concentrations of airborne fungal contamination, on a general basis, are less indoors than outdoors. Conversely, buildings with elevated indoor concentrations represent those with an indoor source of fungal contamination.

Mitigation of extensive fungal contamination in buildings (i.e. more than a few small spots, square feet of contamination) requires the following to safely remove the contamination:

• Isolation of the contaminated area (negative pressure)
• Respiratory and skin protection for workers
• Physical removal of the growth (amplification) sites
• Physical removal of uncleanable porous surfaces such as carpeting
• HEPA vacuuming of all indoor surfaces
• Post-mitigation air clearance testing

With respect to workers in fungal contaminated buildings, the OSHA General Duty Clause, Section 5, Subsection A, and the Hazard Communication Standard require that employees be notified by employers of potentially hazardous work conditions.

Application of biocides (e.g. bleach) are not recommended as they do not remove the fungal contamination but rather kill the spores and dead fungal spores still contain all the toxins that live fungal spores have plus those associated with the biocide. Nor are biocides effective in preventing re-growth of the fungal contamination. If moisture intrusion re-occurs then re-growth will occur as a result of the deposition of new viable fungal spores following the biocide treatment. The only way to insure no further re-growth is to insure that the moisture intrusion problems have been solved.