The rules in the Quest state
The spaces marked with a falling blocks show where the ceiling is dangerous. Any player who moves onto one of these squares must roll a die. If he rolls a 5 or 6, he will lose one Body point from falling masonry. If the player is wearing a helmet, and has the helmet card, then he will only lose a Body point on the roll of a 6. Monsters are not affected by the falling block squares, as they are familiar with the passages. Do not place the falling block tiles onto the gameboard.
I always took this as a special rule, a special exception, intended for this quest only, that the falling block icon on the map was intended to depict this new "dangerous ceiling" feature instead of the usual use of this icon in combination with the arrow icon as used elsewhere in the quest book to indicate a falling block trap.
So, setting aside the minor point that "player" should read "player character" (and pausing only momentarily to note that "has the helmet card" shows that the original version of the game expected players to actually have the equipment card so cards limited equipment) I always assumed the following;
1. This new feature isn't a trap and cannot therefore be found through searching or disarmed/removed (the text doesn't mention the word "trap")
2. It affects every player character that moves onto one of the indicated squares, but does it affect them every time they step onto each of the indicated squares or is each one a one-off event that only affects them the first time them step onto a marked square?

= one hit
= one hit & pushback
= cancels one hit
















