Incoming solar radiation (ionized particles) doesn't recognize the human conventions of "north" or "south" - thus will be the same at 70N as at 70S. Although it may depend a bit on the season (local "summer" or "winter" months).
The main issue with the polar regions is that the ionized particles tend to follow the lines of Earth's magnetic field. They are focused like a flock of ICBM's into trajectories aimed into the polar regions, thus producing the Auroras (Australis and Borealis) - which are ionizing particles hitting the atmosphere molecules and making them glow (oxygen, red or green; nitrogen, blue or crimson). Thus the amount (and any risk) will be higher at 70N/70S than at 20N/20S.
If you are flying in the polar regions, and see the Aurora right overhead - you
are in the "line of fire."
