Our pastor's son-in-law was working on a job site just before Xmas, when a mason accidentally dislodged a step board (2" x 6") which headed down and pegged him in the head.

While his helmet was Listed, and a decent commercially available brand (AFAIK), it shattered, and part of the injury was chunks of plastic in his head, along with the resultant swelling from the impact.

He survived, and it appears he'll be making a significant recovery (thank goodness).

Scary stuff!