Mold and Libraries

Not only is mold extremely damaging for your health (You Vs. Mold), but it can be quite detrimental to property, as well. This is especially relevant in a library that’s filled with thousands of fragile books.

Mold at the University of Illinois Library

So, what happens if a mold outbreak occurs at a library? The Rare Book and Manuscript Library at the University of Illinois at Urbana Campaign experienced this issue in 2008. A conservator first discovered the mold issue while browsing for a book. Home to over 300,000 volumes of books plus audio visual materials, artifacts, framed art and more, the RBML couldn’t afford a mold outbreak.

The discovery of mold began an 8 month process to save the materials in the library. The library officially closed on February 25, 2008 and the remediation process began. An inspection of the two story library showed that while the mold was widespread, nothing was irreparably damaged yet. This made it crucial to begin controlling the environment and avoiding any permanent damage. To do this, dehumidifiers were brought into the library to lower the humidity and maintain a consistent humidity level.

Once the library was stabilized, a mycologist was brought in to assess the damage. He determined the species of mold was aspergillus sp. It was also determined that the mold likely began during a spike in humidity the previous Fall.

At this point, an intense item-by-item examination began, which took over 60 hours. This confirmed that the mold was widespread throughout the collection and on a variety of materials including leather, paper and cloth. The highest concentration of mold appeared to be near the HVAC system.

Once assessed, it was time to clean the collection. With the help of a remediation company, the entire collection plus the storage areas, building structure and HVAC systems were cleaned. Over the 10 weeks of cleaning, the books were cleaned, restored, or replaced as needed. The storage areas and building structure were cleaned using a vacuum equipped with a HEPA filter, then wiped down with anti-microbial agents. Temporary walls were constructed to divide the library into sections. Negative pressure was then used to prevent the clean sections from being contaminated again. The air handling units were cleaned in a similar manner using both HEPA vacuum cleaning and anti-microbial agents.

The Rare Book and Manuscript Library was a unique restoration project that presented some challenges. First, the two story structure with no elevator made it difficult to access the entire building with restoration equipment. Plus, there was a lack of outlets to use restoration equipment. In addition, all of the materials were quite fragile and tightly packed within the library. Fortunately, after months of work, the library was able to reopen on May 12th, 2008.

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Mold Prevention

As evidenced by the experience of the University of Illinois, mold remediation for a library is time consuming and costly. Luckily, there are some ways to help prevent mold growth in libraries.

First of all, it is crucial to monitor the humidity and temperature in the library. A good way to do this is with a handheld hygrometer. A hygrometer is easy to use, plus it allows you to check multiple areas, which may have different conditions. In order to prevent mold growth, the humidity needs to be below 60% RH. In addition, you don’t want the temperature to be too high. As the air temperature increases, it becomes capable of holding more moisture. Mold is most likely to grow above 80° F so it’s important to keep the temperature below that mark.

Once temperature and humidity rise above these thresholds, there is a typically a 48-72 hour window to lower readings before an outbreak could occur. If mold growth is discovered, it is crucial to act as quickly as possible to limit the exposure. Because there is a limited amount of time to act, it can be useful to plan which restoration company to use ahead of time. If it seems that maintaining the proper environment is problematic then installing a dehumidifier may be the answer. A dehumidifier with a built-in humidistat will automatically maintain the desired humidity without the need to constantly check it.

Another important factor in protecting a library from mold is maintaining the HVAC system. Obviously, this contributes to maintaining a lower temperature and humidity. Mold outbreaks are more common in the summer when temperatures rise and the HVAC systems have a higher load. This means it’s important to stay on top of maintenance and ensure the HVAC is working properly.

A final factor in preventing mold growth for libraries is building maintenance. Problems with the building structure can let in outside air and moisture, leading to issues. Because of this, it’s important to monitor all aspects of the building including the roof, doors, and windows. For example, a leaking roof or faulty door could be the start of excess mold. If an issue is discovered, it should be fixed as soon as possible. In addition, it’s important to perform thorough cleaning on a regular basis. Regular vacuuming and dusting is a crucial step in keeping away moisture.

While it may seem like there is a lot involved to prevent mold, most tasks fall under regular maintenance. The most important steps are to maintain a stable humidity and temperature while also performing consistent maintenance and cleaning. These factors will go a long way in preventing mold from occurring in a library.

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Sources Used:
Livingston, Preston. “Mold Remediation and Prevention in a Library Environment .” Texas Library Journal, vol. 91, no. 2, 2015, pp. 60–61.,
Oliveira, Nicholas Ferraz de. “RBML Closure – University Library.” University Library, University Of Illinois, 8 Feb. 2008,
“Rare Book & Manuscript Library Mold Remediation Project.” Staff Website, University of Illinois , rbml_mold_remediation/.