U.S. Nuclear Regulatory Commission
Question 221: Since the posting requirements are all in terms of deep dose equivalent, what requirements should be followed when posting for low energy beta radiation?
Answer: Unless the beta particle can deliver a dose at a tissue depth of 1 cm, the area does not require posting as a radiation area (20.1902 (a)), high radiation area (20.1902 (b)), or very high radiation area (20.1902 (c)); however, posting for airborne radioactivity area (20.1901 (d)) and for areas or rooms in which licensed material is used or stored (20.1901 (e)) needs to be considered for beta emitters. See Questions and Answers 57, 74, and 85 for more information.
(Reference: 10 CFR 20.1902, 10 CFR 20.1901)