5.2 Fumigation

The term fumigation is used in this study to include any treatment which relies on exposure to the fumes or vapor of a biocidal compound to kill mold. The idea of fumigation is appealing to most librarians and archivists. It does not involve the treatment of individual items and is therefore not costly in terms of staff time. Large numbers of items can be treated at one time, in either fumigation chambers or by sealing areas of the building and fumigating entire collections. The reality of fumigation is far less appealing when considered in terms of its uncertain effectiveness, lack of residual protection, possible alteration or damage of materials, and toxicity to staff and users.

Methods of Fumigation

Fumigation may be carried out in various ways, using a variety of fumigants, some better than others, but all hazardous. If fumigation is necessary, it should be carried out by licenced professionals whenever possible.

Of the fumigation chambers commonly in use, those which incorporate a vacuum are most effective in eliminating mold. The vacuum allows greater penetration of the fumigant, and there is a possibility that it may also have adverse affects on the mold structure, removing oxygen required for growth and possibly rupturing the spores themselves. Vacuum chambers are however extremely expensive to purchase and install. Ethylene oxide is the fumigant most often used in vacuum chambers, and requires an additional chamber for the aeration of materials after fumigation in order to rid organic materials of residual toxins. Sulphuryl flouride is also used in vacuum chambers for the eradication of insects. It is not effective as a fungicide, and very little testing has been done regarding its toxicity and effect on organic materials.

Non-vacuum fumigation chambers are most often used with thymol and orthophenyl phenol vapors as the fumigant. Many institutions maintain small cabinets for fumigation of a limited number of items. Often these fumigation cabinets are improvised from old refrigerators or metal cabinets which were never intended for use as fumigation chambers. These improvised cabinets are particularly dangerous for staff exposed to them on a regular basis. Occassionaly there are recommendations in the literature that fumigation may be carried out in plastic bags. The standard plastic bag available for the disposal of household trash is not a vapor barrier, and cannot contain fumigation vapors effectively.

Fogging of entire areas is most often carried out by professional fumigation companies, and should never be attempted by untrained, unlicenced staff. If fogging is necessary, librarians should know precisely what fumigant was used, and scrupulously observe all restrictions regarding access to the area and exhausting the gas after fogging. Organic materials may retain toxic vapors and information regarding hazards to staff and users should be obtained from the company carrying out the fumigation.