The requirement for low-level environmental radiological monitoring has led to the development and widespread use of thermoluminescent dosimeters (TLD's) for this purpose. TLD's offer a sensitive and accurate means for integrating exposures over extended periods of time, and are especially well suited for determining environmental radiation levels in the vicinity of nuclear facilities. The EERF, as well as several other organizations, has used the ER and G TL-15 TLD for environmental radiological monitoring.