e and our possessions play host to tiny insects and to legions of molds and mold spores. As a consequence, those of us who collect antiquarian books must constantly guard against the spread of such pests among rare tomes. The K. Garth Huston, Sr., Rare Book Room of the ASA’s Wood Library-Museum of Anesthesiology (WLM) is no exception.

Craning the 2.5-ton air conditioner onto the HVAC penetration through the ASA headquarters building’s roof.

Despite earlier cleanups and the freeze-drying of mold-affected volumes, the WLM experienced a second major mold infiltration of its third-floor Rare Book Room. Flying in from Dallas, Texas, WLM Trustee Charles C. Tandy, M.D., consulted emergently with an antiquarian book conservator. Their short-term strategies focused on ionizing and vacuum cleaning remedies. First, the collection was cleaned with a high-power vacuum system. Then the Rare Book Room’s circulating air was purified and sanitized by portable “radiant catalytic ionization technology.”

One of two HEPA fans placed into the Rare Book Room ceiling.	Looking up through the hallway ceiling and out through the roof penetration, awaiting the 2.5-ton air conditioner.

Subsequently — in concert with its benevolent landlord, ASA — the WLM moved aggressively to renovate the Rare Book Room as part of a long-term solution to repel attacks from molds and other threats on the priceless collection. In order to remove current molds and prevent future infestations, the WLM Trustees opted for an independent, filtered air supply of the Rare Book Room (now standard in the industry) as well as for tight control of room temperature and relative humidity. As the final part of general clean-up, the existing carpeting was replaced with vinyl composition tile flooring.

Mimicking the laminar flow of biohazard “isolation rooms” and the particle-free “clean rooms” of the computer age, the Rare Book Room’s system for heating-ventilation-air conditioning (HVAC) has now penetrated the roof of the hallway outside in order to capture fresh air to mildly oversupply the volume of air exchanged into the Rare Book Room. To minimize mold’s access to the rare books’ environment, both fresh outside and recycled air are now filtered by two high-efficiency particulate air (HEPA) filters designed to remove 99.7 percent of measured particulates.

Jacking the dehumidifier up into the hallway ceiling.	Sealed lighting fixtures and heavy ceiling tiles in grommeted gridwork.

Consider an analogy. Anesthesiologists are often amused by the classic preoperative consultations of our cardiology colleagues with respect to patients’ blood pressures and heart rates: “Not too high, not too low; not too fast, not too slow.” Experts on minimizing mold growth have similar environmental expectations regarding temperature and relative humidity: “Not too high, not too low; not too wet, not too dry.” Mold and insects thrive in temperatures greater than 75 degrees F. High temperatures are chilled by a large air conditioner mounted on the rooftop, which discourages mold growth by minimizing pockets of stagnant air. Proper placement of ductwork openings further optimizes air flow and limits the growth of mold.

One of three smoke dampers for closing ductwork during a fire.

As long as they exceed freezing, cool temperatures are typically preferred in order to fight mold. Wide fluxes in temperature actually encourage infestation. Heat is supplied by an electrical heater rather than by the previously used hot water system. Overall the thermal systems for the Rare Book Room aim for a temperature range of 70-73 degrees F. As much as possible, plumbing and condensation risks have been resituated outside the Rare Book Room ceiling, a move that also prevents “too wet” concerns that follow.

Steam humidifier that resides in a room adjoining the Rare Book Room.

In combating mold, control of humidity is frankly more important than control of temperature. Relative humidity greater than 55 percent encourages the spread of both insects and mold. Additionally, paper-threatening acid forms more readily under humid conditions. To minimize rises and fluxes in humidity, a dehumidifier has been placed in the ceiling outside the Rare Book Room and patched into the HVAC system.

 In addition overly dry air embrittles adhesives, papers, leathers and even photographic emulsions. As with temperature changes, fluxes in relative humidity threaten a collection more rapidly than any particular given extremes. When the Rare Book Room requires more humidity, an adjoining room’s steam humidifier can supply it. The current Rare Book Room system is designed to keep relative humidity at 40-45 percent.

As a final note, the two WLM librarians and the WLM curator salute ASA Building and Member Services Manager Robert M. Wallace for his hard work in coordinating this vital project for the WLM’s Rare Book Room. Indeed these upgrades should finally succeed in “breaking the mold” and protecting our precious antiquarian books housed in the Huston Rare Book Room for ASA members and the anesthesiology community for decades to come.

George S. Bause, M.D., M.P.H., is Clinical Associate Professor, Case Western Reserve University, Cleveland, Ohio.