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eman

A unit of concentration of radioactive material, = 10⁻¹³ curies per cubic centimeter, or 3.7 × 10⁻³ becquerels per cubic centimeter.

At the meeting of the International Radium-Standards Commission in 1930 a speaker asserted that the eman had been in use since 1921.

M. Curie, A. Debierne, A. S. Eve, H. Geiger, O. Hahn, S. C. Lind, St. Meyer, E. Rutherford and E. Schweidler.
The Radioactive Constants as of 1930. Report of the International Radium-Standards Commission.
Reviews of Modern Physics, volume 3, number 3, pages 427-445 (July 1931).

Page 432: “Eman = 10⁻¹⁰ curie per liter (10⁻¹³ curie/cm³) is a term used since 1921 for the Rn content of the atmosphere as a concentration unit.”