Press Room

Temporary Closure of the Rare Books Department

by mschuler

The Rare Books Department at the Boston Public Library will be temporarily closed for 5 to 10 weeks due to the discovery of mold in scattered locations in the department.

This is a proactive measure to safeguard the approximately 500,000 books and 1,000,000 manuscripts in the collection and prevent the spread of mold spores.

BPL is working with Polygon, experts in temporary climate solutions and document recovery services, to clean the collection and address the situation. Because the majority of the manuscripts are housed in archival boxes, the cleaning will focus on the Department’s books.

Some more fragile items may need additional conservation care, which will be identified during the cleaning by Polygon.

The Rare Books Reading Room and Lobby are the only areas within the Rare Books Department that are accessible to the public, and those areas are now closed to the public.

The air quality in the Rare Books Department is being monitored and no health or safety risks have been identified.

BPL will work to reopen areas of the Rare Books Department as cleaning progresses and to provide limited public service.



The temperature and humidity in the Rare Books Department is monitored on an ongoing basis, and interventions, such as dehumidifiers are implemented as conditions require.

BPL believes that extended periods of high heat and humidity this summer were likely a factor in activation of mold spores.



Monday, 9/14: Staff member identifies mold in the Rare Books Department on the British Museum Catalogue of Printed Books.

Tuesday, 9/15 & Wednesday, 9/16 – Rare Books Department management and BPL Facilities begin work to determine extent of issue, cause, and engage outside expertise.

Thursday 9/17 – Additional high grade dehumidifying equipment brought into the space to bring the relative humidity levels down.

Thursday, 9/17 – Containment is mobilized and clean up and remediation work begin.

A second wave of humidity regulating equipment will be online no later than Monday, September 21.


For additional information about the Rare Books Department visit:


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