The Earth's magnetic field shield us from radiation (charged particles) from outer space. If you see the Earth's field pattern , along the equator the field is parallel to the surface and at the poles the field is vertical. Charged particles spiral along the B field lines. The charged particles in the upper atmosphere will not spiral towards the surface around the equator but into the poles. Therefore , going to the poles can be a health hazard due to exposure to radiation. Jetsetting around the world is also a health hazard as we tend to come into the path of charges spiralling along the B field.
pic taken from www.vortexmaps.com
