Did you know Library and Archives Canada has an Environmental Monitoring Program in place in most areas where collections are stored? We collect information on the temperature and humidity levels in the collection storage areas to ensure that the material is held in the optimum conditions so it will remain in its current state as long as possible. If material is stored in too hot an environment, the rate of degradation or discolouration increases, especially if the items are chemically unstable, such as colour photographs. If stored in too cold an environment, items can get brittle and tend to crack. The worst case is where the temperature rapidly fluctuates between too warm and too cold: the worst of both conditions!
Relative humidity is also critical. Too high a relative humidity can cause items to start to swell, oxidize and grow mould, whereas too low a relative humidity can cause items to shrink and crack. Books are especially susceptible to humidity problems, with their multiple components and the wide variety of materials used to construct and bind them.
Below are two of the many different types of data loggers used at Library and Archives Canada to monitor environmental conditions. They range from old-fashioned looking linear chart recorders to web-enabled electronic data loggers.
With monthly data dumps and random spot checks, we are able to monitor the collection storage conditions to ensure that the temperature and humidity are at the optimum levels, in accordance with internationally recognized standards. So there you have it:EMP, what it is, and why we do it at Library and Archives Canada!