VOLUME 10

NO.3

MOLD HAS BEEN RECOGNIZED

as a serious threat to thesafety and longevity of

library materials for many years. Its abilityto weaken, discolor, and destroy booksand other paper items is well known.Although most librarians and archivistsare aware of mold’s negative effects oncollections, many do not have first handexperience in dealing with an active moldbloom until mold is unexpectedly discov-ered in their library’s stacks. In 1991,employees at the University of OklahomaLibraries received a quick course in moldabatement, when mold was found grow-ing in a book stack area.1

OU’s Bizzell Memorial Library is madeup of three joined structures erected in1932, 1958, and 1982. The mold bloom,initiated by a combination of roof leaksand malfunctioning air handling systems,occurred in the original 1932 portion ofthe building. The book stacks in this areaare commonly referred to as “the decks”,

and theyhouse older,Dewey-classifiedbooks on steelshelving. Low ceil-ings, narrow aisles,and heavy doors thatclose off the decksfrom the other morefrequently used areasof the library createan environment that often has less thanadequate airflow. The lack of good air circulation combined with the accidentaladded moisture and heat produced a climate well-suited for mold growth.

As with any situation in which a moldbloom occurs, attention was first given tostabilizing the temperature and humidityby repairing the roof leaks and the airhandling system. When these factors werebrought under control, library workersbegan using a thymol solution to wipemold from the books. When concerns

The lack ofgood air circu-lation combinedwith the acci-dental addedmoisture andheat produced aclimate well-suited for moldgrowth.

Archival Products

NEWSChlorine Dioxide: A Treatment for Mold in Libraries by Kristina L. Southwell

arose about possible carcinogenic effectsof thymol, the treatment was halted and a microbiologist was consulted for adviceon an alternative chemical treatment.Library administrators chose chlorinedioxide for its effectiveness as a sporicide,and for its safety level for library employ-ees and patrons.

Chlorine dioxide is commonly used asa biocidal agent in water treatment appli-cations, paper manufacturing, and manybranches of the food processing industry.2

It can be used in both aqueous andgaseous forms, and has recently gainednotoriety as the agent used to combatanthrax in the Hart Senate Building onCapitol Hill, and U.S. postal facilities inNew Jersey and Washington, D.C.Because of its history of use by variousindustries, statistical data on chlorinedioxide’s safety is available from the U.S. Environmental Protection Agency,and the U.S. Occupational Safety andHealth Agency.3

A chlorine dioxide wet wipe solutionwas used by workers to clean the exteriorof each book in the affected section of the1932 decks. Employees wore gloves andapplied the chemical with cheeseclothpads. The books were spread out anddried, then reshelved. Shortly thereafter,additional problems with the air handlingsystem occurred that permitted moremold to grow in the same area. Once thesystem was repaired, a hand-held foggerfilled with a gaseous solution of <0.02%activated, stabilized chlorine dioxide wasused to fog the decks, as well as the airsystem’s intake and outtake vents. Despitea later problem with the air handling system that caused temperature andhumidity to fluctuate, no further moldoutbreaks have occurred in this area.

In the summer of 1997 a similar prob-lem occurred in a small section of the

library’s 1958 addition. Following a cam-pus-wide air conditioning failure, moldwas discovered growing in a closed collec-tions storage area. Like the decks, this areacontained books and collections on steelshelving in a room with minimal airflow.Attempts to control the mold bloom

C H L O R I N E D I O X I D E : A T R E A T M E N T F O R M O L D I N L I B R A R I E S – c o n t i n u e d

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Chlorine diox-ide is commonlyused as a bioci-dal agent inwater treatmentapplications,paper manufac-turing, andmany branchesof the food pro-cessing industry.It can be usedin both aqueousand gaseousforms.

OU decks where the 1991 mold bloom occurred.

Self-activating chlorine dioxide packets hung in one ofOU’s special collections areas.

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through wiping the materials with liquidchlorine dioxide were unsuccessful due tothe unusually high mold spore count pres-ent in the room. The combination ofcleaning the affected volumes, plus stricthumidity and temperature controls weresimply not enough to effectively managethe situation. Instead of fogging the areain the same manner as the decks, libraryadministrators decided to try chlorinedioxide in a new format. Self-activatingpackets of chlorine dioxide marketed bythe Engelhard Corporation under thebrand name “Aseptrol” were used.4 Thesmall packets contain powder that reactswith humidity in the air to release chlorinedioxide in gaseous form. A total of sixpackets were hung with wire ties betweenthe bookshelves, in a closed area thatmeasures about 12,000 square feet. Thisapproach stopped the mold bloom, andno subsequent infestations have beenfound in this area.

As a result of the success of chlorinedioxide in these areas, the UniversityLibraries continue to use chlorine dioxidepackets to control mold growth in emer-gency situations, as well as in areas thatrequire regular treatment due to fluctuat-ing temperature and humidity levels. Inthe spring of 2003, a steam pipe burstunder the branch library that housesarchitecture materials, creating an idealhot and humid environment for a moldbloom. Chlorine dioxide packets wereimmediately hung after the steam pipewas repaired, and to date no mold growthhas been detected.

The University Libraries also havefound that chlorine dioxide packets areparticularly well suited for controllingmold growth in special collections areas,which often consist of small, enclosedstorage areas that do not receive muchtraffic from library employees or patrons.

The self-activating chlorine dioxide pack-ets can be hung and left to work withoutrequiring constant monitoring by librarystaff. The regular presence of mold eradi-cation chemicals in areas with unstableenvironments or a past history of moldinfestation provides an added level ofsecurity for susceptible collections.

As a follow-up study, in 2000 theUniversity Libraries conducted a test onthe library materials that were treatedwith chlorine dioxide in the 1991 moldoutbreak in the decks.5 This test wasdesigned to determine whether any unin-tended negative effects resulted from thebooks’ exposure to chlorine dioxide. Thetests focused specifically on paper acidityby measuring the pH levels of the paperin books that had been wiped and foggedwith chlorine dioxide, and comparedthem to similar books that had no expo-sure to chlorine dioxide. The tests wereconducted using a microcomputer pHmeter with a flat sensor electrode attach-ment. The meter allowed for direct measurement of paper pH, expressed innumeric values, and had an added tem-perature electrode that compensated forfluctuations in temperature during thetesting process. A group of 250 books that

C H L O R I N E D I O X I D E : A T R E A T M E N T F O R M O L D I N L I B R A R I E S – c o n t i n u e d

As a result ofthe success ofchlorine dioxidein these areas,the UniversityLibraries con-tinue to usechlorine dioxidepackets to control moldgrowth in emer-gency situations,as well as inareas thatrequire regulartreatment dueto fluctuatingtemperatureand humiditylevels.

Test instruments used to measure paper acidity after theuse of chlorine dioxide.

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had been exposed to chlorinedioxide were compared to asimilar group that received no chlorine dioxide treatment.The results were satisfactory,showing that the treatedgroup’s average pH registeredat 5.22, and the untreatedgroup’s average pH was 5.31.An independent means t testwas performed on the pH statistics, which showed thatno significant difference in pH levels (T-value = 0.943)existed between the paper oftreated and untreated books.

Many libraries with moldproblems may find that propertemperature and humiditycontrols and non-chemicaltechniques (such as book vac-uuming with HEPA-filteredmachines) work fine to control a moderate outbreak.However, those who find thatstandard treatments are notenough to stop mold growthcan consider chlorine dioxide

as an alternate solution. TheUniversity of OklahomaLibraries continues to usechlorine dioxide to treat prob-lem areas within the collec-tions, and will continue toevaluate and document itslong-term effectiveness.

NOTES:

1. An in-depth treatment of the University ofOklahoma Libraries’ early use of chlorinedioxide against mold is available in PatriciaL. Weaver-Meyers, Wilbur A. Stolt, andBarbara Kowaleski’s “Controlling Mold onLibrary Materials with Chlorine Dioxide: AnEight-Year Case Study,” The Journal ofAcademic Librarianship 24 (1998): 455-458.

2. Simpson, G. D., R. F. Miller, G. D. Laxton,W. R. Clements. “A Focus on ChlorineDioxide: The ‘Ideal’ Biocide.” Online,Chlorine Dioxide Water Treatment ResourceCenter. Available: http://www.clo2.com/reading/waste/corrosion.html (accessedMay 12, 2003).

3. Toxicological Review of Chlorine Dioxideand Chlorite, U.S. Environmental ProtectionAgency (Washington, D.C.) Available:http://www.epa.gov/iris (accessed May 12,2003); the most current statistics from OSHA are available at http://www.osha-slc.gov/SLTC/healthguidelines/chlorinedioxide/recognition.html (accessedMay 12, 2003).

4. The Engelhard Corporation no longer supplies Aseptrol packets. Similar chlorinedioxide packets can be obtained from mostboating supply stores, which refer to themas “mildew control bags” for use on boatsand boat houses.

5. For further information on chlorine dioxideand paper acidity testing, see KristinaSouthwell’s “The Use of Chlorine Dioxide asa Mold Treatment and Its Effect on PaperAcidity: A Case Study.” The Journal ofAcademic Librarianship 28 (2002): 400-405.

Kristina L. Southwell is Assistant Professor of Bibliography/ ManuscriptsLibrarian at the University of OklahomaLibraries, Western History Collections, 630 Parrington Oval, Room 452, Norman,Oklahoma 73019. She can be contacted atklsouthwell@ou.edu.

C H L O R I N E D I O X I D E : A T R E A T M E N T F O R M O L D I N L I B R A R I E S – c o n t i n u e d

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Star Bright mildew control bags absorbexcess moisture, cleans air particles,and inhibits fungi growth.

5

Your collectionsprovide awealth of foodsources for mold.The spores liedormant, requir-ing only theproper combi-nation of envi-ronmental con-ditions—heat,water (or highhumidity), andstagnant air—to bloom andbegin the feast.

AN OUTBREAK OF MOLD IS ONE

of the most common problemsin any archive or library in a

humid climate. In South Carolina, nosummer ever passed without at least onecall from a frantic archivist or librarianwho had just discovered mold growing inhis/her collection. In many cases, moldblooms in the days following a temporaryfailure of the air conditioning system. Itdoesn’t have to be a collection of olderarchival materials, either. While at theSouth Carolina Department of Archivesand History, I received calls from hospitalrecord rooms, county court clerks, and college library periodical rooms, as well as from special collections, historic housemuseums, and archives. Mold will infestvirtually any type of organic-based materi-al: film, paper, cloth, wood, or leather.

Mold is such a successful organismbecause there are so many different typeswhich thrive on an astounding array offood sources. Mold also has an incrediblyefficient reproductive mechanism—thespore. The atmosphere and the collectionscontain hundreds of different types ofmold spores. Your collections provide awealth of food sources for mold. Thespores lie dormant, requiring only theproper combination of environmental con-ditions—heat, water (or high humidity),and stagnant air—to bloom and begin thefeast. Even if you maniacally clean yourcollections before you put them on theshelves, you cannot be sure of a clean envi-ronment. An old air conditioning systemmay be producing millions of mold spores,spewing them into the atmosphere andonto the collections. This was the case atthe South Carolina Department of

Archives and History, and this articlerelates what we did when we thought wehad mold actively growing on our materi-als, only to discover that we had a majorthreat to our collections and personnel inthe building’s ventilation system.

Initially we became concerned aboutmany volumes with large patches of black“fuzzy” smudges on bindings, text blocks,and in the gutters and end sheets. A closerlook revealed hundreds of pages of mildewdamage and brightly colored mold stains.We had no records showing that this appar-ent mold had been there when the volumeswere accessioned. There had been majorfailures of the heating ventilating and airconditioning (HVAC) system the summerbefore we first took note of this damage. Aswe surveyed the collections in an organizedfashion, we began noting and bagging thedamaged books and many boxed records.

We made a deliberately informed deci-sion about bagging the items. We recog-nized that an active mold infestation wouldgrow more rapidly inside a plastic bag. Butwe had no storage facility to which wecould transfer these materials. Concernedabout the spores spreading to the rest of thecollection, and worried about the respirato-ry health of the staff members who had towork in the stacks, we opted for the bags.

We took further action. We submittedsamples of the mold to the labs at theDepartment of Health and EnvironmentalControl. We expected confirmation of ourworst fears, but their response was incon-clusive. While they could not get the sam-ples to grow in cultures, they informed usthat this was no guarantee that we did nothave active mold spores in the collection.Concerned that we might have another

Coping With a Mold Outbreak in the Archivesby Pat Morris

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Working on thetheory thatmold will notgrow on cleanmetal, we optedto vacuum outthe HVAC sys-tem. There arecommercialservices that dothis work. Weused a firmcalled DuctDoctor. Theyused no wateror chemicalsand created acombination ofvacuums andhigh poweredair pressure toclean all theducts.

HVAC failure which could leadto a major bloom of mold inthe collections, we pursued fur-ther expert advice by contactinga member of the university’sbiology department. An experi-enced mycologist, Dr. Gerald T.Cowley, came on site and tookextensive samples, not just fromthe bagged materials, but alsofrom the shelving, walls, and airducts. His test results confirmedthat the patches of fuzzy“growth” on the collectionmaterials did not contain viablemold spores. However he didfind that we had alarminglyhigh levels of viable mold sporeseverywhere else in the building—about100 times more mold spores inside ourbuilding than were present in the open airoutside the building. The air samples fromthe HVAC vents inside the building wereespecially “rich”, generating dozens of different types of molds in the cultures.Some of these were harmful to humanbeings and many fed primarily on cellu-lose—the main ingredient in paper. Hepointed out one species of mold in particu-lar; it is so successful in breaking down cellulose that the paper industry uses it intheir manufacturing process to break downold paper for recycling.

What did this mean for us? Our twenty-five-year-old HVAC system was generatingviable mold spores in significant amountsevery day. As long as the system main-tained temperatures below 75 degrees andrelative humidity below 55-60%, our collections would probably remain free ofactive mold growth. During the previoussummer’s HVAC malfunction, the relativehumidity rose far above 60% for morethan two weeks while the maintenancecrews worked to resolve the problems. We

knew we were on thin ice. Itwould take millions to replacethe HVAC system, but wecould clean the mold out of thesystem and clean up the stacksfor a few hundred thousanddollars. Using the informationfrom our consultant, we con-vinced the legislature to allocatefunds to clean up the collec-tions and the HVAC system.

We reviewed a number ofoptions. We considered killingthe mold by applying fungi-cides. One vendor promised usgreat results with a solution thatcould be sprayed on the collec-tions and the shelving and in

the duct work. It would kill all live moldsand leave behind a fungicidal layer to pre-vent any new outbreaks. The problem withthis “solution” is that it might kill mostblooming mold, but it couldn’t kill viablemold spores. Over time, the layer leftbehind as a fungicide would become afood source for mold spores. If the relativehumidity rose high enough long enough,the mold would begin to grow again.Furthermore we were uncertain about howthe chemical treatment would interact withthe various bindings, film, and photo-graphs in the collection.

The archival literature generally provid-ed information on techniques (some out of date) that deal with mold in smallamounts. Nothing really addressed anentire building full of archival materials. In the end, we abided by the general prin-ciples of modern conservation: use as fewchemical treatments as possible; be surethat treatments are reversible.

Working on the theory that mold willnot grow on clean metal, we opted to vacuum out the HVAC system. There arecommercial services that do this work. We

C O P I N G W I T H A M O L D O U T B R E A K I N T H E A R C H I V E S – c o n t i n u e d

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2

Mold Spores1) Memnoniella2) Claolosporium

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C O P I N G W I T H A M O L D O U T B R E A K I N T H E A R C H I V E S – c o n t i n u e d

used a firm called Duct Doctor.They used no water or chemi-cals and created a combinationof vacuums and high poweredair pressure to clean all theducts. All filters were replaced,and they found filters well up inthe system that had clearly beenthere since the equipment wasinstalled. They cleaned outthings like soda cans and sheetsof insulation, all thickly coveredwith dirt and grime. Next, wehad all the boxes, books, andother containers in the collec-tion cleaned with HEPA filteredvacuum cleaners. Before cleanedcontainers and volumes wereput back on the shelves, the shelving waswashed with a three-to-one solution of plainwater and isopropyl alcohol. The alcoholwas added primarily to help the water evap-orate more quickly. All walls, ceilings, andfloors were also vacuumed.

After the general clean-up, we continuedto retain the services of our consultingmycologist. We purchased an air samplingkit for his use, and he continued takingsamples from the stacks and work areas.Spore counts had dropped dramatically. Hecontinued to find some viable spores, butthe numbers were well below the samplestaken outside the building for comparison.More than half the samples from the stacksyielded no viable spores at all.

Finally we carefully checked all newmaterials added to the collections. Any sus-picious items were vacuumed by the con-servation staff before they were added tothe collections. While doing this work, thestaff wore properly fitted respirator filtersdesigned for the filtration of spores (notjust dust). They used Nilfisk vacuums withadequate HEPA filtration and appropriateextensions for delicate work. All old boxes

were exchanged for new cleanarchival containers.

We found that our HVACsystem functioned more effi-ciently. Of course we continuedmonitoring the temperature andhumidity to be sure that anyelevation of either was addressedby plant personnel immediately.As an added precaution, weinstalled large utility fans (man-ufactured by BARCO) in all thestacks to circulate the air whenthe HVAC system malfunc-tioned again, which wasinevitable, given its age.

Within five years the stateconstructed a new archives facil-

ity. The design parameters of the new facil-ity included strict environmental standards for the stacks: 60° F and 40% relativehumidity. The only way to prevent a futuremold problem is maintenance of accept-able environmental standards.

We learned a number of lessons fromour experience.

1. Most of the preservation literature concentrates on coping with small moldinfestations. As research continues, adviceand techniques for handling mold change;but the most up-to-date information onissues related to mold (though not alwaysspecific to archives and libraries) is EllenMcCrady’s publication and website TheMold Reporter (http://moldreporter.org/). A convenient collection of brief publica-tions on mold is also available through theConservation On Line (CoOL) website(http://palimpsest.stanford.edu/bytopic/mold/). Hilary Kaplan’s article reprintedthere is very helpful, particularly its infor-mation on the acquisition of proper safetygear. The National Parks publication provides some outdated advice on

After the gener-al clean-up, we continued to retain theservices of our consultingmycologist. Wepurchased anair sampling kitfor his use, andhe continuedtaking samplesfrom the stacksand work areas.

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1) Alternaria2) Ganoderma basidio

spores

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Rainbow Vacuums, but they do includesources for other equipment includingNilfisk vacuums. One of the best articlesavailable on the nature of biological infestations is from the museum literature,written by Canadian conservator MaryLou Florian (http://www.uni-muenster.de/Forum-Bestandserhaltung/kons-restaurierung/sch-florian.shtml). TheChicora Foundation published a solidpiece entitled Mold: Understanding the Problem and Recovering Safely. Twelve pages long, it’s a handy reference for $2.00 plus shipping fees if you order lessthan 50. Order it through their websitehttp://www.chicora.org/; find it throughthe search engine. 2. Avoid chemical solutions. They do notkill all the spores and may cause healthproblems. Continuing research has usuallyrevealed that the chemicals that kill moldwill weaken the paper. The chemicals mayleave a residue that will one day become afood source for mold spores.3. There is no “quick fix” once you’ve had amold outbreak. After you have eliminatedthe blooming mold, you will always have tobe vigilant about cleanliness, temperature,and humidity levels. If your mold outbreakoccurred because of a water leak, repair thestructural damage and install water alerts.Continue checking for re-bloom.4. Clean all new acquisitions before they

are placed in storage with the rest of yourcollection. At an absolute minimum, trainstaff to be alert to signs of mold andmildew when they take in new materials. 5. Exposing the infested materials to sun-light or ultraviolet light will not kill moldeffectively, but it can irreversibly damageyour materials. Limited exposure to sun-light will speed the drying process, but airdrying using fans is just as effective anddoes less harm in the long term.6. It’s possible to curtail outbreaks ofactively growing mold by circulating airwith fans when the humidity levels rise.But you must be conscientious in advisingpeople in the area that they risk exposureto mold spores. Some people may havevery sensitive respiratory reactions. 7. Document any mold damage you findduring the initial inventory; and then doc-ument any remedial action you take duringacquisitions and processing.

Pat Morris was at the South Carolina Department of Archivesand History from 1987 to 2002. She is now a preservationlibrarian at the University of Colorado at Boulder. She can becontacted at Patricia.Morris@colorado.edu.

Avoid chemicalsolutions. Theydo not kill allthe spores andmay causehealth problems.

C O P I N G W I T H A M O L D O U T B R E A K I N T H E A R C H I V E S – c o n t i n u e d

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