Have you seen the explanations of radiation where they say flying (as a passenger) is about equal to the dosage of a dental X-ray (or something similar)? Someone who spends their career getting exposed at that rate might be worth making them a shield.
It's *not possible* to make a shield. The cosmic radiation that reaches that altitude is highly energetic and highly penetrating—enough so to go through 3 meters of water—and would be completely unaffected by lead sheets. Any easily-shielded types of cosmic radiation have already been blocked by the atmosphere.
It's not worth it. Like, you could mandate planes fly 100 meters lower, but a lead coating would be so heavy. Let's say a 737 with a max weight of 70 tons. Covering the top half with lead would mean a 200 square meter sheet, and at 1cm thick it would weigh more than 20 tons.
