Radioactivity is the term used to describe disintegration of atoms. The atom can be characterized by the number of protons in the nucleus. Some natural elements are unstable. Therefore, their nuclei ...

The EPA says radon should be mitigated if air quality tests show four picocuries — a unit of radioactive decay — per liter, and people should start considering mitigation at two picocuries.

Air monitoring stations regularly detect elevated levels of radon gas—a radioactive decay product of radium—with concentrations up to 25 picocuries per liter, five times the action level set by health ...

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