The atmosphere of Mars protects it's surface from micrometeorites. How significantly does the Martian atmosphere reduce radiation in comparison with, for example, the Moon's surface or open space?
Radiation on Mars is an issue,
Mars has no global magnetic field comparable to Earth's geomagnetic field. Combined with a thin atmosphere, this permits a significant amount of ionizing radiation to reach the Martian surface.
Readings by the Curiosity rover during its first 300 days on Mars were between 200 and 250 micro-Gray per day.