Introduction
A study of the occurrence and distribution of dissolved radon in the ground water of Chester County was undertaken by the U.S. Geological Survey (USGS) in cooperation with the Chester County Water Resources Authority and the Chester County Health Depart-ment. The results of this study are published in a technical report by Senior (1998). This fact sheet summarizes the key findings pre-sented in the technical report. Much of the background information on radon was taken from Lindsey and Ator.