Packages and overpacks with surface dose rating higher than _____ mSv/h are not permitted for air transport.

• A. 2
• B. 1
• C. 5
• D. 10

Answer: (B)

Air transport imposes strict radiation-safety limits on what can be shipped. The surface dose rate is the radiation level measured on the outer surface of a package. For air shipments, this surface rate must not exceed 1 mSv/h. If the surface dose rate is higher than that, the package isn’t permitted to be carried by air, because it would pose too great a potential exposure to handlers, crew, and the public in the event of handling or an emergency.

The transport index (TI) is related but different: it reflects the dose rate at 1 meter from the package and is used for classification and labeling. Higher surface rates would typically correspond to higher TI and tighter controls, but the specific air-transport rule cited here focuses on the 1 mSv/h surface limit.

Other options would allow higher surface radiation levels, which would increase exposure risk; the one with 1 mSv/h is the safe, regulatory limit for air transport.