Magazine article Texas Library Journal

Mold Prevention and Remediation in a Library Environment

Magazine article Texas Library Journal

Mold Prevention and Remediation in a Library Environment

Article excerpt

To properly prevent mold growth in a library, three components are necessary: 1) monitoring of humidity and temperature, 2) proactively maintaining the building's heating ventilation and air-conditioning (HVAC) system for proper performance, and 3) good housekeeping. Mold outbreaks in libraries are a common occurrence and never having had one previously does not mean it will not occur. I have seen four mold outbreaks in a library environment, and would like to share my experience.

Temperature and humidity monitoring and mold prevention

Every library needs to have a monitoring system for building temperature and relative humidity to insure that the collection is in a safe environment. If either building temperature or humidity gets out of acceptable ranges, mold will develop on library materials. Mold spores are always present. When conditions become favorable, mold will grow.

The number of library materials that become contaminated with mold depends on the material type and the severity of the environment rate. If temperature and humidity levels continue to increase, the amount of materials that are contaminated with mold will increase. The secondary result is mold spores becomes aerial and will move to other areas in the collection and start growing.1 An initial outbreak of mold can be followed by other waves of contamination.

Other factors that contribute to mold growth are poor air circulation, dust, and high humidity in the air outside the building.2 If ceiling air ducts have a balanced air flow (meaning each vent is pushing about the same amount of air), air is constantly moving and, in equal proportion, a drying affect is created which helps reduce humidity.3 Simple cleaning is fundamental to preventing mold. Dust removal from books should be done with a HEPA vacuum cleaner.4 Vacuuming is more effective than cleaning with a dust cloth.5 The shelves should be cleaned with Lysol wipes and dried before replacing the books.

If a library's current HVAC system is old or possibly falls under the category of deferred maintenance, the difficulties of controlling the environment are compounded. Monitoring the library's temperature and humidity can be done with a very reasonable investment in a digital thermo/hygrometer and labor. Various thermo/hygrometers (both wall and handheld units) are available for purchase.

I would strongly recommend that at least one handheld unit is purchased that is professional grade, since a proper reading of temperature and humidity and appropriate action is a necessity. A handheld device allows readings in different areas of the stacks since it is very probable that the temperature and humidity readings will be differ relative to HVAC performance at various locations in the library.

A library environment should maintain relative humidity within a range of 35% to 50% with a variance plus or minus 5%. If relative humidity surpasses 60%, then conditions for mold growth are possible.6 Temperature also plays a factor in controlling the environment. Heat causes evaporation, increasing relative humidity. The amount of moisture air will hold is relative to the temperature. As temperatures increase, the air's capacity to hold more moisture also increases. When the air cools, the moisture is released and could then fall on library materials.

Therefore, libraries need to monitor building temperatures as well. Once the temperature surpasses 80 degrees (at any level of humidity) mold growth is possible. The range recommended for temperature is 72 - plus or minus five degrees.8 Archival departments sometimes have different range requirements, depending on the type materials in the collection. The topic of what is considered proper temperature and humidity ranges for a library environment is a greatly debated issue. Be prepared to get differing opinions.


As a general rule of thumb, once humidity or temperature is out of range, there is a 48-to-72 hour window to bring the readings back into an acceptable range or risk a mold outbreak. …

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