This term originated during the Manhattan Project, which was the name of the effort to develop the atomic bomb during the 1940s. Most of the scientists involved in that project were physicists. Those physicists responsible for health and safety concerns were called health physicists.
The name stuck and today they can be found at work at nuclear power plants, on military submarines, in hospitals (where they are called medical physicists), and at research universities, to name just a few.
Health physics provides the practical means for protecting workers, the general public, and the environment from harmful radiation exposures. At EPA, health physicists work with other scientists to provide the technical basis for radiation protection policies and regulations.