Mould Outbreak – An Immediate Response

Protect staff

Take preventive measures to protect staff working in the facility. [Information on appropriate personal protective equipment (PPE) is provided below.] People with allergies or those with asthma should not be in contact with affected material or where the mould infestation is located.

Isolate artifacts

It is important to isolate the mould contamination. If only one or a few artifacts are contaminated, isolate them. If many artifacts are involved, isolate the entire collection area. This will prevent mould spores from dispersing into clean areas of a collection and the rest of the building. Artifacts can be isolated by placing them in a sealed box or bag. If large, they can be wrapped in plastic sheeting. If the artifacts are wet or damp, this should be a temporary measure until they can be dried. If the artifacts are dry, they can stay in containers or wrapped in plastic until they are cleaned of visible mould growth. If the collection area must be isolated, seal the entrance and return air intake vents with tape and heavy gauge plastic/polyethylene sheeting. This will prevent mould spores entering clean areas of a building.

Isolate and control access to affected artifacts or contaminated areas to reduce exposing people to mould. People entering the isolated area or opening sealed objects should always wear the appropriate PPE.

Determine the extent of the mould infestation, consider the available resources, and determine whether the infestation can be handled in-house or outside help is required.

Identify and eliminate the causative agent

Determine the cause of the mould outbreak and take immediate action to correct it. This may include measures to lower the relative humidity, to increase air circulation, to lower room temperature, and to remove any standing water. If necessary, employ a company that specializes in desiccant drying to dry the affected facilities and furnishings, such as carpets and drapes.

Deactivate the mould

The mould is actively growing if it feels damp and smears when brushed or if a mouldy smell is present. Deactivating the mould will stop its growth and prevent further damage to the artifacts. This can be done either by air drying or by freezing, as discussed below. Once the artifact is dry, mould can be removed. Keep the dry artifact isolated and in a sealed container until it can be cleaned. This will prevent any inactive, but still viable, spores from dispersing.

Air drying

Artifacts can be air dried by lowering the relative humidity and increasing air circulation. Because the mould spores of most species are easily airborne, it is important to conduct air drying in a way that does not disperse mould spores and to take measures to prevent the spores from dispersing throughout the building. Seal the return air vent and, if possible, open windows to vent air outdoors. Select an isolated room, with a minimum of furniture, that is easy to clean afterwards. Allow artifacts to air dry naturally or use fans. If using fans, place them so the airflow is directed away from the artifacts. This will limit spore dispersal and keep the drying process slow enough to reduce physical distortions, such as fine checks or cracks that can result from an abrupt decrease in the object's moisture content. Objects made of a thick layer of organic material, or objects that are composed of different elements (such as inlays or veneers) joined together, are the most likely to undergo high physical stresses leading to damage during air drying.

If air drying indoors cannot be accomplished without dispersing mould spores, it is preferable to either freeze the material, air dry a few at a time in a fume hood, or dry the material outdoors. Air drying outdoors should be done on a clear day, in a sheltered spot out of direct sunlight. Be sure to keep the objects away from people and building air-intake systems, and bring them in at night.

Freezing

Freezing is a quick method of killing actively growing mould. However, although a mould's vegetative growth will freeze and break down, the spores are able to withstand the cold temperatures and remain viable.

Freezing is a good option when there are numerous water-damaged or mouldy objects as this method eliminates the urgency to safely dry all wet artifacts within a short time frame. But freezing is not appropriate for all artifacts. In general, it is safe for textiles, furs, feathers, leather, paper, and wood. However, it is not recommended for glass plate negatives, oil paintings, or acrylic paintings. If in doubt, check with a conservator first. Before freezing, seal the object in a clear polyethylene bag or wrap with polyethylene film and seal with tape.

Household horizontal chest freezers, which generally operate between -18°C and -28°C, can be used for a small number of objects. Freezing on a large scale requires a larger freezer. Large walk-in freezers can be rented. Freezer trucks can also be rented and brought to a site. The labour-intensive drying process can then be postponed until the staff is fully organized and has secured the space, time, resources, and people to deal with the artifacts.

Respiratory protection

For mould infestations in heritage collections, particulate filters from the N series (N for not resistant to oil) are generally appropriate. Filters described as N100 offer the greatest protection against particulate matter. These filters are also referred to as HEPA (high-efficiency particulate air) filters.

Some fungi produce volatile organic compounds that cause unpleasant odours, including the characteristic mouldy smell associated with damp areas or materials. The health effects of exposure to microbial volatile organic compounds (MVOCs) have not been well-studied. They may be responsible for headache, dizziness, and eye and mucous membrane irritation (Levetin 1995). When a mould smell is present, a filter that combines HEPA and organic vapour cartridges is recommended. Some particulate disposable respirators incorporate nuisance-level organic vapour relief and may be appropriate for some circumstances. Half-face and full-face respirators and some powered air purification respiratory systems (PAPRs) can be fitted with combination HEPA and organic vapour cartridges that protect against MVOCs.

Respirators, including disposable respirators, should be test fitted by a qualified individual to ensure a proper fit. Respirators should always be stored in a clean area or in a bag to avoid buildup of particulate matter on the respirator. At the end of each day of use, respirators should be cleaned according to the manufacturer's instructions. Used respirator filters will support mould growth. To prevent this, allow the respirator (and filters) to air out before storing them in a sealed bag.

Disposable particulate respirators

Disposable respirators are inexpensive and maintenance free, but proper use requires carefully reading and closely following the manufacturer's instructions. In order to get a good fit from a disposable respirator, follow the instructions on the package. Disposable respirators are not appropriate for every individual. If improper facial contact is made with the respirator, it may actually increase the concentration of mould spores being inhaled. These devices, therefore, are not appropriate for people with facial hair. If a disposable respirator is used more than once, be sure to air it out after use and store it in a clean environment. Stuff the inside of the respirator with clean tissue to ensure it remains clean. If the respirator becomes damaged, soiled, or breathing becomes difficult, discard it.

Half-face respirators

A half-face respirator consists of an assembled face piece worn over the mouth and nose. Cartridges selected to protect against a hazardous environment are attached to the face piece. Particulate and combination cartridges are available. Half-face respirators are more expensive than disposable respirators, but are re-usable because the cartridges can be replaced. Half-face respirators are available in different shapes, styles, and sizes. They are not appropriate for people with facial hair.

Full-face respirators

A full-face respirator consists of an assembled face piece worn over the mouth, nose, and eyes. Cartridges selected to protect against a hazardous environment are attached to the face piece. Particulate and combination cartridges are available. Full-face respirators can be re-used by replacing the cartridges as required. Full-face respirators are available in different materials, styles, and sizes. They are not appropriate for people with facial hair.

It is not necessary to wear protective goggles with a full-face respirator, but the seal of the respirator may be compromised if the person wears prescription eyeglasses. It may be necessary to consult with a reputable technical consultant of respiratory equipment to select the most appropriate full-face respirator. Full-face respirators or PAPRs are recommended when dealing with extensive mould growth.

Powered air purification respiratory systems (PAPRs)

PAPRs are positive-pressure airflow respirators that deliver a steady supply of filtered air. Filtered air passes through the breathing tube and into the headpiece. PAPRs protect individuals with facial hair and do not require test fitting.

Goggles

Protective goggles must also be worn when dealing with mould. The appropriate, recommended goggles are not ventilated and must accommodate a disposable or half-face respirator. If the user wears prescription eyeglasses, tight-fitting yet comfortable goggles may be difficult to locate. In this case, full-face respirators or PAPRs may be an option.

Gloves

Protective gloves should be worn when handling mouldy material. Due to concerns about latex allergies, vinyl (PVC) or Nitrile gloves are recommended. Disposable gloves should be replaced as required. Torn gloves should be replaced immediately. Hands should be washed with soap and water after handling contaminated material, even when gloves have been worn.

Protective clothing

When dealing with mouldy material, protective clothing must be available for all personnel and it must be properly worn and fastened. Coveralls and protective hair and shoe covers should be used when significant amounts of mould spores might be released into the air. Disposable clothing is recommended, but re-useable protective clothing (lab coats or coveralls) may be appropriate for small and medium-sized levels of contamination. Protective clothing must not be worn outside the contaminated area. It should be removed on-site and washed in hot water and bleach.

Discarded disposable PPE

There are no special requirements for discarding contaminated PPE. However, it is important to exercise caution when handling and discarding these items. Place disposable clothing, gloves, etc., in thick (6 mil) plastic garbage bags or two layers of thin plastic garbage bags. Seal and discard the bags in an outdoor garbage container.

Canadian Standards Association (for more information regarding respirators)

• CSA Standard Z94.4-02 "Selection, Use, and Care of Respirators"
• Telephone: 416-747-4000 or 1-800-463-6727

Fisher Safety Canada

• Telephone: 1-800-243-7437 (customer service in Canada)
• Telephone: 1-877-676-3639 (safety customer service in Canada)
• Telephone: 1-800-772-6733 (customer service in the United States)
• Fisher Safety Canada website

Lab Safety Supply

• Telephone: 1-800-356-0783 (Canada and the United States)
• Telephone: 1-800-356-2501 (technical assistance)
• Telephone: 608-754-7160 (International)
• Lab Safety Supply website

General Information

Guidelines for Mould Remediation

Laboratories

• AIHA Accredited Labs
• Aerotech Labs
• Environmental Microbiology Laboratory, Inc.