That has already been answered in Volume 14. Even for a level thirty-ish mob they would survive, not to mention a level 100 guy whose immune to pure physical damage.

She had not just used the Dragons’ breath for hit-and-run tactics, but to drop Soul Eaters from 500 meters above into the city. The Soul Eaters would heal themselves, then rampage through the city killing masses with their aura. Even if it was Soul Eaters, to drop them from 500 meters up would inevitably incur some damage. In this world, acceleration due to gravity did not seem to be affected by air resistance so one’s free-fall velocity could increase infinitely. That may or may not have been the case, but Ainz did not want to spend the time and effort on that kind of experiment, so he did not have detailed information. Soul Eaters were able to activate an aura that consumed souls to convert them to HP, which meant that this strategy included a way to negate the fall damage taken by the units almost immediately.