While there is always a risk of impact events, it's an entirely acceptable risk for a fixed exploration outpost above ground. It poses less of a threat than the one faced by crews aboard the ISS. On the moon they don't have to contend with an incredible amount of man-made space debris zipping around at various altitudes and orbital planes in addition to micrometeoroids. They track the larger pieces, but still there is plenty unaccounted for in orbit.
Personally, I'd feel more secure on a fixed outpost above ground at the south pole of the moon that I would orbiting Earth in the ISS for six months in regards to impact events.
An underground base could be even more protected than a fixed base on the Moon's surface, though.