(March 2005, 795KB PDF, 77 pages). In support of the NASA Public Health ApplicationS of Earth Science (PHASES) program, this report reviews the confidentiality and related ethical issues in the use of geospatial data for public health purposes. It includes both current and historical references to the ethical,legal, economic, and technical issues associated with confidentiality concerns. The report also provides examples of policies, procedures, and other strategies used to protect the confidentiality of geospatial data.