In all situations, the underlying cause of water accumulation must be rectified or fungal growth will occur. Any initial water infiltration should be stopped and cleaned immediately. An immediate response (within 48 hours) and thorough clean up, drying,and/or removal of water damaged materials will prevent or limit mold growth. If the source of water is elevated humidity, relative humidity should be maintained at levels below 60% to inhibit mold growth. Emphasis should be on ensuring proper repairs of the building infrastructure, so that water damage and moisture buildup does not recur. Three levels of abatement are described below. The size of the area impacted by fungal growth primarily determines the type of remediation. The sizing levels listed are based on professional judgment and practicality; currently there is not adequate data to relate the extent of contamination to frequency or severity of health effects. 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. The listed remediation methods were designed to achieve this goal, however, due to the general nature of these methods it is the responsibility of the people conducting remediation to ensure the methods enacted are adequate. The listed remediation methods are not meant to exclude other similarly effective methods. Any changes to the remediation methods listed in these guidelines, however, should be carefully considered prior to implementation.

Non-porous (e.g., metals, glass, and hard plastics) and semi-porous (e.g., wood, and concrete) materials that are structurally sound and are visibly moldy can be cleaned and reused. Cleaning should be done using a detergent solution. Porous materials such as ceiling tiles and insulation, and wallboards with mare than a small area of contamination should be removed and discarded. Porous materials (e.g., wallboard, and fabrics) that can be cleaned, can be reused, but should be discarded if possible. All materials to be reused should be dry and visibly free from mold. Routine inspections should be conducted toconfirm the effectiveness of remediation work.

The use of gaseous, vapor-phase, or aerosolized biocides for remedial purposes is not recommended. The use of biocides in this manner can pose health concerns for people performing the remediation as well as for people returning to the treated space if used improperly. Furthermore, the effectiveness of these treatments is unproven and does not address the possible health concerns from the presence of the remaining non-viable mold. The purpose of mold remediation is to remove the mold to prevent human exposure and damage to building materials and furnishings. It is necessary to remove the mold contamination, not just to kill the mold. Dead mold is still allergenic, and some dead molds are potentially toxic. In most cases, it is not possible or desirable to sterilize an area; a background level of mold spores will remain in the air. These spores will not grow if the moisture problem in the building has been resolved.

Remediation efforts should be conducted during non-business hours whenever feasible.

Level I: Small Isolated Areas (10 contiguous sq. ft. or less)

  • Regular building maintenance staff can conduct remediation. Such persons should receive training on proper clean up methods, personal protection, and potential health hazards. This training can be performed by a Health and Safety Professional or a person trained in microbial remediation as part of a program to comply with the requirements of the Cal-OSHA Hazard Communication Standard.
  • Respiratory protection (e.g., N95 disposable respirator), in accordance with the Cal-OSHA respiratory protection standard, is recommended. Gloves and eye protection should be worn. Disposable coveralls are optional.
  • The immediate work area should be unoccupied. Vacating people from spaces adjacent to the work area is not necessary but is recommended in the presence of infants, persons recovering from recent surgery, immune suppressed people, or
  • people with chronic inflammatory lung diseases (e.g., asthma, hypersensitivity pneumonitis, and severe allergies).
  • Containment of the work area is not necessary. Dust suppression methods, such as misting (not soaking) surfaces prior to remediation or sealing contaminated surfaces prior to removal, are recommended.
  • Contaminated materials that cannot be cleaned should be removed from the building in a sealed plastic bag. There are no special requirements for the disposal of moldy materials.
  • The work area and area used by remedial workers for egress should be cleaned with a damp cloth and or mop and a detergent solution.
  • All areas should be left dry and visibly free from contamination and debris. Level II: Mid-Sized Isolated Areas (10 – 100 contiguous sq. ft.)
  • Regular building maintenance staff can conduct remediation. Such persons should receive training on proper clean up methods, personal protection, and potential health hazards. This training can be performed by a Health and Safety professional or a person trained in microbial remediation as part of a program to comply with the requirements of the Cal-OSHA Hazard Communication Standard.
  • Respiratory protection (e.g., half face negative pressure air purifying respirator with P-100 HEPA filters), in accordance with the Cal-OSHA respiratory protection standard, is recommended. Glove, eye protection and disposable protective coveralls should be worn.
  • The immediate work area should be unoccupied. Vacating people from spaces adjacent to the work area is not necessary but is recommended in the presence of infants, persons recovering from recent surgery, immune suppressed people, or people with chronic inflammatory lung diseases (e.g., asthma, hypersensitivity pneumonitis, and severe allergies).
  • Cover using polyethylene sheeting from ceiling to floor affected area with a slit entry and covering flap; maintain area under negative pressure with HEPA filtered fan unit exhausted to the outside. Block supply and return vents within containment area.
  • Dust suppression methods, such as misting (not soaking) surfaces prior to remediation or sealing contaminated surfaces prior to removal, are recommended.
  • Contaminated materials that cannot be cleaned should be removed from the building in a sealed plastic bag. There are no special requirements for the disposal of moldy materials.
  • The work area and areas used by remedial workers for egress should be HEPA vacuumed and cleaned with a damp cloth and or mop and a detergent solution.
  • All areas should be left dry and visibly free from contamination and debris.

Level III: Extensive Contamination (greater than 100 contiguous sq. ft.)

A health and safety professional with experience performing microbial investigations should be consulted prior to remediation activities to provide oversight for the project. The following procedures at a minimum are recommended:

  • We can do Wall Checks to determine if there is Hidden Mold behind walls.
  • Personnel trained in the handling of hazardous materials equipped with full-face respirators with HEPA cartridges (in accordance with Cal- OSHA respiratory protection standard) and disposable protective clothing covering both head and shoes should perform the work.
  • Containment of the affected area: should include complete isolation of work area from occupied spaces using plastic sheeting sealed with duct tape (including ventilation ducts/grills, fixtures, and any other openings). The use of an exhaust fan with a HEPA filter to generate negative pressurization and airlocks and decontamination room should be used during the remediation.
  • Contaminated materials that cannot be cleaned should be removed from the building in a sealed plastic bag. There are no special requirements for the disposal of moldy materials.
  • The immediate work area should be unoccupied. Vacating people from spaces adjacent to the work area is not necessary but is recommended in the presence of infants, persons recovering from recent surgery, immune suppressed people, or people with chronic inflammatory lung diseases (e.g., asthma, hypersensitivity pneumonitis, and severe allergies).
  • The outside of the bags should be cleaned with a damp cloth and a detergent solution or HEPA vacuumed in the decontamination chamber prior to their transport to uncontaminated areas of the building. The contained area and decontamination room should be HEPA vacuumed and cleaned with a damp cloth and/or mop with a detergent solution and be visibly clean prior to the removal of isolation barriers.
  • Air monitoring in accordance with NIOSH protocols for bio-aerosols should be conducted prior to occupancy to determine if the area is fit to reoccupy. *Note: Although the level of personal protection, engineering controls and work practices suggested in these guidelines is based on the total surface area contaminated and the potential for remediator and/or occupant exposure, professional judgment should always play a part in the remediation decisions. These remediation guidelines are based on the size of the affected area to make it easier for remediators to select appropriate techniques, not on the basis of health effects or research showing there is a specific method appropriate at a certain number of square feet. The guidelines have been designed to help construct a remediation plan. The remediation manager will then use professional judgment and experience to adapt the guidelines to particular situations.