Are ski helmets useful?

My neighbors ski instructors in Deer Valley have been slow in adopting ski helmets. Not so long ago, one of them even hinted to me that they were overrated by asking me: “Do you wear a helmet while you drive your car?” I don't, but I'm pleased to wear one when I ski.

A week or so ago, my grandson slid on a steep, sleek hill and ended up in the trees. He actually hit them with both thighs and got bruises that hurt him for the next couple of days.

He could have as easily hit these same trees by going head first and then, his helmet would have serve its purpose. Sometimes, falls aren't that spectacular or speeds not that high, and this is precisely when a helmet fulfills it protective role.
 
Falls are part and parcel of skiing or snowboarding, and I'm convinced that if even a helmet protects in only 20 percent of the cases (I do believe its more than that), they're well worth wearing.