Radioactive particles are encountered at typically very low levels in the environment from natural sources such as minerals containing radioactive elements, background cosmic rays, solar flux, and radon gas. Radioactive materials can also be produced in manufacturing, nuclear medicine and industrial operations such as nuclear power plants, nuclear laboratories and radioactive waste handling and disposal.

Exposure to radioactive particles can be severely detrimental to humans and the ecosystem and regulatory agencies have set concentration limits, standards and specified analytical testing methods to detect radioactivity in environmental matrices. Entities that deal with radioactive substances, and some supplies of potable water or wastewater treatment (when required by authorities), must perform radioactivity-level determinations.