How to Sanitize Collections in a Pandemic

Conservators weigh in on the mysteries of materials handling during COVID-19

March 27, 2020

COVID-19 materials cleaning

Keeping libraries safe is important for both workers and guests. But during the current COVID-19 pandemic, questions about how to do that—particularly when it comes to materials and surfaces—have complicated answers.

It’s an unprecedented situation. Conservators, who are experienced in diagnosing and repairing collection damage, say that historical information on sanitizing library materials is lacking. Besides a bit of anecdotal evidence from a 2019 Smithsonian Magazine article, there’s very little historical data available, says Evan Knight, preservation specialist at the Massachusetts Board of Library Commissioners: “There’s nothing published or shared from previous epidemics.”

It’s also a challenge to sift through evolving research. A January study in the Journal of Hospital Infection reported that coronaviruses similar to SARS-CoV-2, the one responsible for COVID-19, can persist on some inanimate surfaces (such as metal, glass, and plastic) for as long as nine days and on paper for four or five days. Meanwhile, recent data from the National Institutes of Health indicate SARS-CoV-2 is detectable in aerosols for up to three hours, on copper for up to four hours, on cardboard for up to 24 hours, and on plastic and stainless steel for perhaps only two to three days.

The pandemic also presents challenges of a more philosophical nature. “[It’s] difficult to reconcile the public health requirements of this pandemic with our mission,” says Jacob Nadal, director for preservation at the Library of Congress (LC), which closed to the public on March 12 and has canceled events through July 1. “It is heartbreaking to see how this disease forces us to step back at exactly the time we want to step up.”

Time is the best disinfectant

Yet stepping back may be the best defense against a still developing threat. The easiest, safest, and most inexpensive disinfectant is time. “This pandemic is a unique situation for most conservators, so we don’t know a lot about disinfecting generally, and this virus specifically,” says Knight. “Our view is that prophylaxis, or preventive measures, are best.”

Fletcher Durant, director of conservation and preservation at the University of Florida’s George A. Smathers Libraries, suggests that all libraries follow the March 17 ALA recommendation to close to the public. “Isolation for a minimum of 24 hours, and preferably 14 days, is the best disinfectant,” he says. “It is simply the best and safest thing that we as librarians can do at this time.” Durant says it’s about protecting libraries as well as the public. “Libraries could provide a risk vector for the spread of the disease, which, beyond the direct health impacts, could reduce the public trust in libraries,” he says.

That also means libraries should plan to stay closed until the risk of public infection is eliminated. “We would be the first to say that we are not equipped to make recommendations on virology, bacteriology, or medical matters,” says Nadal. “Quarantine past the viability of the virus is the best plan.”

Cleaning and sanitizing

Some libraries, however, have a mission that precludes complete quarantine. LC, for example, continues to support Congress while it’s in session, which requires some staff to be onsite. Other libraries are maintaining services with curbside checkouts of materials. That means additional sanitizing methods are warranted.

Internal hard surfaces, including tabletops, door handles, book drops, and computers, should be professionally cleaned. Experts also note that virtual reality headsets have been flagged as a risk factor, and libraries should postpone their use. “If at all possible, hire a professional cleaning service that has appropriate training and personal protective equipment to do this work,” says Nadal. “This is a time for exceptional caution.”

Any staff working onsite should institute thorough hand-washing, especially when handling books or any shared objects in the library. “There are no studies that specifically answer the question of how transmissible the coronavirus might be from the most common library materials, [such as] coated and uncoated paper, book cloth, or polyester book jackets,” Nadal says. “We have to look for high-quality information and evaluate it critically to determine how well it applies to our particular concerns.”

Avoiding materials damage

Knight says librarians should be cautious when using cleaning solvents on books and other potentially fragile library materials. “I am not aware of a ‘least damaging’ cleaner or disinfectant, especially for any objects of obvious lasting value,” he says, explaining that the risks to books subjected to aqueous cleaning or disinfecting include water damage and weakened hinges and joints. “Books wrapped in polyester or polyethylene can be more reasonably cleaned and disinfected, and strong library-binding buckram cloth coverings can probably withstand the enhanced cleaning too,” he adds. “But again, if one is planning to clean and disinfect collections, even among poly-covered volumes, they should understand and accept that there will be collection damage.”

There’s evidence that certain methods may not be effective anyway. “Common misperceptions may be that spraying or wiping the outside of a volume with Lysol, alcohol, or bleach is sufficient to denature the virus across the entire volume,” says Durant.

Ultraviolet (UV) light also poses a potential risk to collection materials because of its high intensity. And because of how difficult it is to confirm that every page has been exposed to the light, the effort could prove fruitless. “UV germicidal irradiation has generally been found to be effective at exposure of 2–5 millijoules per square centimeter [mJ/cm2],” says Durant. “However, for this exposure to be effective, it must be complete exposure, [which is] something that is almost impossible to achieve with bound books. It’s certainly not as effective as simply isolating the books for at least 14 days.”

Yet even as libraries continue to learn new preservation procedures, certain constants remain. “This is a good time to think about the role of libraries as stewards of memory and culture,” says Nadal. “We are going to be closed for a period of time, and our ethic of constant service will make this painful. Keeping materials quarantined and out of circulation will be frustrating. [But] we are keepers of a long history, and our foremost obligation now is to make sure that there is a long future for the recorded knowledge and creativity entrusted into our care.”

Further reading

  • Articles from BBC and NPR on how long the coronavirus lasts on surfaces and techniques for surface cleaning
  • Best practices from the Northeast Document Conservation Center for quarantining and disinfecting books returned to the library
  • An outline from Coordinated Statewide Emergency Preparedness Massachusetts on sheltering collections in place and isolation strategies
  • Massachusetts Board of Library Commissioners has collaborated with the Massachusetts Library System on a COVID-19 Response LibGuide
  • The National Park Service’s National Center for Preservation Technology and Training has released a video on disinfecting cultural resources
  • ALA has also put together a page on Pandemic Preparedness Resources for Libraries, as well as this handling guide from the Association for Library Collections and Technical Services
  • Dewey Decibel podcast’s “Libraries Respond to COVID-19” episode
  • Finally, the National Endowment for the Humanities suggests using the Twitter hashtag #CovidCollectionsCare in the coming weeks for more information

Updated Apr. 29, 2020, to indicate extended suspension of Library of Congress events.


Blue heart on purple background with heartbeat graph.

Libraries’ Next “Act” in Health During COVID-19

Libraries Connecting You to Coverage, resources from PLA | Sponsored

Personal protective equipment donated by University of Maryland's Preservation Department

University Libraries Help Hospitals with PPE Donations

Preservation specialists rush to fill shortages of protective gear