25 Pa. Code § 227a.35 – Electron microscope devices.

(a) Labeling. A closed-beam electron microscope device must be labeled with a conspicuous sign bearing the words, ‘‘Caution Radiation—This Equipment Produces Radiation When Energized,’’ or words containing a similar warning.
(b) Maximum radiation level. Radiation levels measured 5 centimeters from an accessible surface of a closed-beam electron microscope may not exceed 0.5 mrem (0.005 mSv) per hour.