Indoor mold

General

Molds and fungi are found every where inside and outside. They can grow on almost any substance when moisture is present. Molds when they reproduce make spores, which can be carried by air currents. When these spores land on a moist surface that is suitable for life, they begin to grow. Molds are essential to the natural breakdown of organic materials in the environment. Without molds we would be inundated with dead organic matter. It has been estimated that 40 percent of United States homes have some form of mold problem.

Health Effects

The problems with mold usually stem from the symptoms and health effects resulting from indoor mold exposure. There is public awareness that exposure to mold can cause adverse health effects, symptoms, and possible allergic reactions. Health professionals are often tasked with the investigation and/or assessment of these health effects on employees and/or the public.

The most common form of hypersensitivity is caused by the direct exposure to inhaled mold spores or hyphal fragments which can lead to allergic asthma or allergic rhinitis. The most common effects are runny nose, watery eyes, coughing and asthma attacks. Another form of hypersensitivity is hypersensitivity pneumonitis (HP). This is usually the direct result of inhaled large spores or fragments in an occupational setting. About 5% of individuals are predicted to have some allergic airway symptoms from molds over their lifetime.

Toxic effects from mold are produced by exposure to the mycotoxins of some mold species, such as Stachybotrys chartarum (S. chartarum). These are often referred to as “Toxic molds” These toxic molds are often implicated as a potential cause of Sick Building Syndrome. A 1993-94 case study based on cases of pulmonary hemorrhage in infants in Cleveland, Ohio originally concluded there was no causal relationship between the exposure and the disease. The investigators revisited the cases and established a link to the exposure to S. chartrum and the infants in their homes. This relationship was later disproved by a different panel and re-evaluation.

Assessment

The first step in an assessment is to determine if mold is present. This is done by visually examining the premises. If mold is growing and visible this helps determine the level of remediation that is necessary. If mold is actively growing and is visibly confirmed the need for sampling for specific species of mold is unnecessary.

Another assessment method is to determine if the premise smells of mold, often described as an earthy or musty odor. However, not all molds produce the telltale mold odors.

These methods are considered to be non-intrusive and only visible and odor causing molds will be found. Sometimes more intrusive methods are needed to assess the level of mold contamination. This would include moving furniture, lifting and/or removing carpets, checking behind wallpaper or paneling, checking in ventilation duct work, opening and exposing wall cavities, etc.

Sampling

When sampling is necessary it should be performed by a trained professional who has specific experience in designing mold-sampling protocols, sampling methods, and the interpretation of findings. The sampling and analysis should follow the recommendations of Occupational Safety and Health Administration (OSHA), National Institute for Occupational Safety and Health (NIOSH), Environmental Protection Agency (EPA), and the American Industrial Hygiene Association (AIHA). Most importantly, when a sample is taken the proper chain of custody should be adhered to. The AIHA offers lists of accredited laboratories that submit to required quarterly proficiency testing.

Three types of air sampling include but are not limited to:

• Air sampling: the most common form of sampling to asses the level of mold. Sampling of the inside and outdoor air is conducted and the results to the level of mold spores inside the premises and outside are compared. Often, air sampling will provide positive identification of the existence of non-visible mold.
• Surface samples: sampling the amount of mold spores deposited on indoor surfaces (swab, tape, and dust samples)
• Bulk samples: the removal of materials from the contaminated area to identify and determine the concentration of mold in the sample.

When sampling is conducted, all three types is recommended by the AIHA, as each sample method alone has specific limitations. For example, air samples will not provide proof a hidden source of mold. Nor would a swab sample provide the level of contamination in the air.

Clean-up methods

The purpose of the clean-up process is to eliminate the mold and fungal growth and to remove contaminated materials. As a general rule, simply killing the mold with a biocide is not enough. The mold must be removed since the chemicals and proteins, which cause a reaction in humans, are still present even in dead mold.

• Wet vacuum

Wet vacuum cleaners are designed to remove water from floors, carpets and other hard surfaces where water has accumulated. Wet vacuuming should only be used on wet materials, as spores may be exhausted into the indoor environment if insufficient liquid is present. After use this equipment must be thoroughly cleaned and dried as spores can adhere to the inner surfaces of the tank, hoses, and other attachments.

• Damp wipe

Damp wipe is the removal of mold from non-porous surfaces by wiping or scrubbing with water and a detergent. Care must be exercised to make sure the material is allowed to quickly dry to discourage any further mold growth.

• HEPA Vacuum

High Efficiency Particulate Air filtered vacuum cleaners are used in the final cleanup of remediation areas after materials have been thoroughly dried and all contaminated materials have been removed. HEPA vacuum cleaners are recommended for the cleanup of the outside areas surrounding the remediation area. During this process the workers wear proper personal protective equipment (PPE) to prevent exposure to mold and other contaminants. The collected debris and dust should be stored in impervious bags or containers in a manner to prevent any release of debris.

• Disposal of Debris and Damaged Materials

Building materials and furnishings contaminated with mold should be placed into impervious bags or closed containers while in the remediation area. These materials can usually be discarded as regular construction waste.

Remediation

If moisture is still present, no level of remediation effort will be successful. The source and cause of the moisture must be eliminated. This can be a very costly step as removal of materials and structural components may be necessary.

The goal of remediation is to remove or clean contaminated materials in a way that prevents the emission of fungi and dust contaminated with fungi from leaving a work area and entering an occupied or non-abatement area, while protecting the health of workers performing the abatement.

Several types of equipment may be used in the remediation process and may include:

• Moisture meter: a tool that measures the moisture level in building materials. It can also be used to measure the progress of the drying of damaged materials. Moisture meters have a small probe that is inserted into the material, or pressed directly against the material's surface. Moisture meters can be used on carpet, wallboard, woods, brick, and other masonry.

• Humidity gauge: measures the amount of humidity in the indoor environment. Often gauges are paired with a thermometer to measure the temperature.

• Boroscope: a hand-held tool that allows the user to see potential mold problems inside walls, ceilings, crawl spaces, and other tight spaces. It consists of a camera on the end of a flexible “snake”. No major drilling or cutting of dry wall is required.5

• Digital camera: used to document findings during assessment.

• PPE: includes respirators, gloves, impervious suit, and eye protection. These items can be used during the assessment and remediation processes.

During the remediation process, the level of contamination dictates the level of protection for the remediation workers. The levels of contamination are described as Levels I, II, and III. Each has specific requirements for worker safety. The levels are as follows:

Level I: Small Isolated Areas (10 sq. ft or less) for example, ceiling tiles, small areas on walls.

• Remediation can be conducted by the regular building staff as long as they are trained on proper clean-up methods, personal protection, and potential hazards. This training can be preformed as part of a program to comply with the requirements of OSHA Hazard Communication Standard ( 29 CFR 1910.1200).
• Respiratory protection (for example, N-95 disposable respirator) is recommended. Respirators must be used in accordance with the OSHA respiratory protection standard (29 CFR 1910.134). Gloves and eye protection should also be worn.
• The work area should be unoccupied. Removing people from spaces adjacent to the work area is not necessary, but is recommended for infants (less than 12 months old), persons recovering from recent surgery, immune-suppressed, or people with respiratory diseases.
• Containment of the work area is not necessary. However, misting and dust suppression is recommended.
• Contaminated materials that cannot be cleaned should be removed from the building in sealed impermeable plastic bags and disposed of as ordinary waste.
• The work area/areas used by workers for access/egress should be cleaned with a damp cloth or mop and a detergent.
• All areas should be left dry and visibly free of from contamination and debris.

Level II: Mid-sized Isolated Areas (10-30 sq. ft) – for example, individual wallboard panels.

• Remediation can be conducted the regular building staff as long as they are trained as for Level I. Respiratory protection, occupation of of the work and adjacent areas, and handling of contaminated materials are the same as for Level I.
• Surfaces in the work area that could become contaminated should be covered with sheet(s) of plastic that are secured in place. This should be done prior to any remediation process to prevent further contamination.
• Dust suppression methods, such as misting (not soaking) surface prior to remediation, are recommended.
• The work area/areas used by workers for access/egress should be HEPA vacuumed and cleaned with a damp cloth or mop and a detergent.
• As with Level I, all areas should be left dry and visibly free from contamination and debris.

Level III: Large Isolated Areas (30-100 sq. ft) – e.g., several wallboard panels

• Industrial hygienists or other environmental health and safety professionals with experience performing microbial investigations and/or mold remediation should be consulted prior to remediation activities to provide oversight for the project.
• It is recommended that personnel be trained in the handling of hazardous materials and equipped wit respiratory protection (N-95 disposable respirator). Respirators must be used in accordance with OSHA respiratory protection standard(29 CFR 1910.134) Gloves and eye protection should also be worn.
• Surfaces in the work area and areas directly adjacent that could become decontaminated should be covered with a secured plastics sheet(s) before remediation to contain dust/debris and prevent further contamination.
• Seal ventilation ducts/grills in the work area and areas directly adjacent with plastic sheeting.
• The work area and areas directly adjacent should be unoccupied. Removing people from spaces adjacent to the work area is not necessary, but is recommended for infants (less than 12 month old), persons recovering from recent surgery, immune-suppressed or people with respiratory diseases.
• Dust suppression methods, such as misting (not soaking) surface prior to remediation, are recommended.
• Contaminated materials that cannot be cleaned should be removed from the building in sealed impermeable plastic bags and disposed of as ordinary waste.
• The work area/areas used by workers for access/egress should be HEPA vacuumed and cleaned with a damp cloth or mop and a detergent.
• All areas should be left dry and visibly free from contamination and debris.

Level IV: Extensive Contamination (greater than 100 contiguous sq. ft in an area).

• Personnel trained in handling of hazardous materials and equipped with:
  • Full face respirators with HEPA cartridges
  • Disposable protective clothing covering the entire body including the head, shoes and hands
• Containment of the affected area:
  • Complete isolation of the work area from occupied spaces using plastic sheeting sealed with duct tape ( including ventilation duct/grills, fixtures, and other openings
• The use of an exhaust fan with a HEPA filter to generate negative pressurization, a decontamination room, and airlocks
• Contaminated materials that cannot be cleaned should be removed from the building in sealed impermeable plastic bags and disposed of as ordinary waste.
• The contained area and decontamination room should be HEPA vacuumed and cleaned with a damp cloth or mopped with a detergent solution and be visibly clean prior to the removal of any isolation barrier.

In conclusion, after the moisture source has been eliminated and the mold growth removed, the premises should be revisited and the reevaluated to ensure the mold growth and the remediation process was successful. The premises should be free of any moldy smells or visible growth.

References

  6.  NEW - CCA 82 - Mould Guidelines for the Canadian Construction Industry (http://www.cca-acc.com/mould/index.html)