Recovery of Mold-Exposed Books

July, 2001

Many people have expressed interest to ensure that library books and textbooks brought from moldy places such as the old Halifax West High School to the new school are free of molds/microbial contaminants.

Background on Molds

Molds can be found anywhere; they can grow on any organic substance, as long as moisture and oxygen are present. There are molds that can grow on wood, paper, carpet, foods, and insulation. It is impossible and not necessary to eliminate all mold and mold spores in the indoor environment. However, when moisture accumulates in or on materials, mold growth will often occur if the moisture problem persists longer than 24-48h. While all buildings have some mold, respiratory and non-respiratory health effects have been reported when larger areas of building materials are contaminated.

Mold growth can be controlled indoors by controlling moisture indoors. Molds reproduce by making spores in the few millionths of a meter size range, small enough to penetrate the lungs. Mold spores waft through the indoor and outdoor air continually. When mold spores land on a damp spot indoors they may begin growing and digesting whatever they are growing on in order to survive. Molds gradually destroy the things they grow on.

Many types of mold exist. All molds have the potential to cause health effects. Molds can produce allergens that can trigger allergic reactions or even asthma attacks in people allergic to mold. Others are known to produce potent toxins and/or irritants. Potential health concerns are an important reason to prevent mold growth and to remediate/clean up any indoor mold growth. (EPA 2001, p 2). Glucans are chemicals found in the cell walls of molds which may cause inflammatory lung and airway reactions. These glucans can affect the immune system when inhaled.(EPA 2001, p 43)

Mold Remediation/Cleanup and Biocides

The purpose of mold remediation is to prevent human exposure and damage to building materials and furnishings. It is necessary to clean up mold contamination, not just kill the mold. Dead mold is still allergenic, and some dead molds are toxic. The use of a biocide such as chlorine bleach is not now recommended as a routine practice during mold remediation (NYC 2000) In most cases, it is not possible or desirable to sterilize an area; a background distribution of mold spores will remain in the air (roughly equivalent to or lower than that level in the outdoor air). These spores will not grow if the moisture problem in the building has been resolved (EPA 2001, p 18) Building materials and furnishings that are contaminated with mold growth and are not salvageable should be double-bagged using 6-mil polyethylene sheeting. These materials can be discarded as ordinary construction waste. It is important to package mold contaminated materials in sealed bags before removal from the containment area to minimize the dispersion of mold spores throughout the building. (EPA 2001, p 18).

Mold-exposed Books, Clean or Discard?

If books had actual water damage or if they were stored in humid conditions, or if the pages had more than 7% water content, then they likely have mold. If the books were not in a wet area, but just exposed to mold spores in the air, then it should be possible to clean them. If you can smell mold then it probably indicates something has been growing, however it could also mean mold VOCs have been absorbed by the paper. Page by page cleaning is very laborious. Instead, read below about fanning books with HEPA suction.

Books, Paper, and Archives.

The clean-up of books, paper, and archives damaged by floods and dampness involves a combination of discarding moldy items, drying out of wet materials, and removal of settled dusts. Fungi can grow rapidly on many of these materials because of the adhesives, gums, starch, etc., often present in book jackets and bindings and also because of the presence of delignified cellulose. Because of the susceptibility of books, paper and archives to biodeterioration, the drying of water damaged or damp materials is of critical importance. Freeze drying of water soaked material can be used in restoration because low temperatures arrest fungal colonization and evaporation of water molecules (subliming) lowers available moisture so that mold growth can not recur. A goal of restoration is to lower the moisture content of paper to its normal range, 5-7% where fungal growth does not occur.

Several simple techniques are available for removing superficial colonization from valuable materials. Miniature aspirators capable of applying a gentle suction to surfaces by a pipette nozzle can be used to carefully remove spores. A small vacuum cleaner can be used to remove spores where a fine screen is placed firmly over the fragile material being cleaned (28). All cleaning activities involving manual removal of colonization should be performed by persons with adequate personal protective equipment and preferably in a biosafety cabinet.

The cleaning of library materials which are not visually colonized but which were stored in buildings with mold growth problems is a challenge because of the enormous amount of paper surface potentially involved. The following activities can be effective in cleaning dusty library materials that had been stored in a moldy environment: (a) Vacuum using a HEPA instrument the top, bottom, and sides of books and files to remove settled dusts. (B) Vacuum (HEPA) and damp wipe the surfaces of shelves, file cabinets, desks and other non-porous fixtures. The visual presence of dust on books and on nonporous surfaces (e.g. shelves) in the library indicates unsuccessful cleaning. (C) Fan the pages of the books, files, and other archives in the immediate vicinity of the suction orifice of a HEPA vacuum. The objective is to reduce the amount of dust present on surfaces of library materials. (Morey 2000).

Mold VOCs can be absorbed/trapped by paper, and books can readily acquire a moldy smell even if there is no visible mould evident. Try airing the books with the pages spread. If airing and vacuuming do not remove the smell, advisors suggested professional treatment for valuable books and the rest should be discarded. Do not wet wipe books or book jackets or wipe with biocide solutions because you are adding water.

Packing and moving books that are currently in use or in storage presents an opportunity to evaluate them for fungal contamination. Be alert for signs of mold contamination when opening boxes or entering storage areas. Note evidence of mold growth or water damage. Sometimes there may be a musty odour but other times spots of mold growth can be seen. Isolate those with evidence of visible mold. Unless of exceptional value, these should be discarded. The Canadian Conservation Institute in Ottawa can be contacted for help in conserving such materials. Avoid handling moldy books without personal protection equipment.

– K. Robinson, CASLE

AIHA (2001) Report of the microbial task force. AIHA, Fairfax, VA USA
EPA (2001) Mold Remediation in Schools and Commercial Buildings.
Morey, P. Personal communication (2000) and Cleaning Procedures for Mold. Proceedings of Healthy Buildings 2000 3:39-48
New York City (2000) Guidelines for the assessment and remediation of fungi in indoor environments.