The ERH is a valuable tool for food product and packaging development as it is an indicator of what hemical reactions may occur during distribution and of how much packaging protection should be designed for the product to give it the required shelf life. Without the protection of a package, the moisture of any food changes in direct proportion to the relative humidity. The rate at which the gain or loss of moisture occurs depends on the makeup of the product, i.e., its hygroscopicity, the temperature and the atmospheric pressure. In packaged products the changes are relatively slow, but at times a significant change can occur within a short period of time. Have you ever eaten soggy potato chips at a picnic on a hot and humid day? Have you ever received moisture test results from the lab that you were convinced were incorrect? If so, perhaps the samples were not properly packaged for transit.