Which radiation from space can affect airline pilots but “never passes through walls”, as the printed teaser asks?

Solution & explanation

The intended source is cosmic radiation: exposure can be higher at flight altitude because less atmosphere lies overhead. The clause “never passes through walls” is false as a general statement; cosmic-ray components have different penetrations and some pass through walls. There is no scientifically correct answer satisfying that absolute wording.

CERN · penetrating cosmic particles ↗ ·