Actress Natasha Richardson?s death after a skiing accident has many on Long Island thinking about the incidence of severe head injuries as a result of common activities.

Richardson fell on a ski slope in Canada on Monday and was reported in critical condition. She was flown to New York City the next day, where she died.

According to the CDC, 1.5 million people suffer from a traumatic brain injury each year. While many die from those injuries, there are more than 5 million survivors of traumatic brain injuries living in the United States.

Head injuries can vary considerably even between patients with similar injuries. Doctors say it?s important to keep in mind that while traumatic brain injuries can occur in car crashes or contact sports, they can also happen as a result of less extreme incidents like falling down stairs or down a beginner ski slope, like in Richardson?s case.

?The unfortunate part about brain injuries is often they're very subtle,? Dr. Jennifer Semel, of St. Charles Hospital, says. ?You don't have to have a serious crash and lose consciousness to have a serious brain injury.?

Liz Giordano, of the Head Injury Association, says her organization?s message is simple: protect yourself against the kinds of head injuries that are preventable by wearing a helmet.

A spokeswoman from the resort Richardson was staying at said she was not wearing a helmet. A statement put out by the resort said the actress fell on a beginners trail and later reported not feeling well.

AP wire reports contributed to this article.Head Injury Association631-543-2245Brain Injury News and Information BlogBIAAHeadInjury Association