The only real way to
reduce the threat of mold in a library is to maintain an
environment that is not hospitable for the germination of
mold spores. The temperature should be 68-72 degrees F,
and the relative humidity of 65% or less. It is important
that the air conditioning system be kept on 24 hours a
day, 7 days a week. Fluctuations in the temperature and
humidity are the cause of many serious mold outbreaks.
What is mold?
Mold and mildew are generic terms for
various types of fungi, which are spread by air currents
and will germinate if they find a hospitable environment.
Once small patches of germinating spores appear, they will
lead to a mold bloom unless measures are taken to contain
What causes mold to grow?
grow on any organic host material that offers suitable
nutrients, including paper, adhesives, bookbindings,
microfilm, slides, videotapes, dust, etc. Books and
paper especially provide a perfect host for mold to
germinate since they are hygroscopic and absorb and hold
A mold bloom in a library indicates that there has been an
increase in relative humidity. This could be caused by any
number of things:
- Changes in the natural
environment (e.g. rainy season in Hawai'i)
- Fluctuation in interior
environment (e.g. turning off the AC at the end of the
day and on weekends)
- Construction/building disasters
(e.g. roofing, leaks)
- Natural disasters (e.g. floods,
How to prevent mold?
Controlled environment is essential to
preventing large-scale outbreaks of mold. This means:
- Moderate, constant temperature
(68-72 degrees F). Turning off Air conditioning causes
fluctuations in temperature and the relative humidity
- Low, constant relative humidity
(if possible less than 60%, max. 65%). Room
dehumidifiers need to be emptied or they can
re-introduce moisture into air.
- Good air circulation. Fans can
be installed to improve air circulation.
- Good Housekeeping. Dust books
and library materials regularly.
- Regularly monitor the library
How to combat a mold outbreak?
First, verify that the problem is mold
(stains from earlier mold damage or silverfish damage can
resemble a mold outbreak). If mold is confirmed, respond immediately and organize a team to
cleanup the mold. If
possible, isolate contaminated materials by bagging them.
Fungicides are not recommended for treating mold in
libraries due to the concerns about both toxicity and
long-term effects on collection materials. Household chemicals (e.g. Lysol, Clorox) are also not appropriate to use on books.
Vacuum books (binding, spine) as well as book trucks,
shelves, and other work surfaces. Using a vacuum with HEPA filter will
prevent spreading or further embedding the mold spores.
Wipe all surfaces and walls with
householf cleaner (e.g. Simple Green) and clean (or
remove) any carpets or drapes in the affected area.
Installing fans after the cleaning
process is completed can improve air circulations and
prevent mold spores from returning.
For more information
and links on mold prevention and management visit the Pest & Mold Resources