By Dr. Christopher Magovern

Skiing and snowboarding are two of the most popular sports in this country.  It's estimated that 9.9 million Americans hurtle down snow-covered slopes every year - and anyone who skis or boards knows that falling is an accepted part of the learning curve for beginners, and an inevitable event among even the most experienced of skiers and boarders.

Thankfully the risk of injury is low.  The risk of being injured on the mountain is 1 in 500, the risk of sustaining a serious head injury is 1 in 5,000, and the risk of being killed on the mountain is 1 in 1 million. In this regard, skiing and snowboarding are safer sports than bike riding or swimming.

Nonetheless, head injuries can and will occur on the mountain, so it is important to take steps to prevent an injury and to know what to do if an injury occurs.  The most common head injury occurs from falling and hitting the snow or ice.  This is a particularly common injury for beginner skiers or boarders.  Skiers usually strike the side of their heads, and boarders usually strike the back of their heads.  Another, more dangerous injury occurs from colliding with a stationary object, commonly another skier or a tree.

In an effort to limit head injuries on the mountain, your goals should be to: 1) prevent these sorts of falls in the first place, 2) decrease your risk of head injury by wearing a helmet, and 3) if you do sustain a head injury, be able to recognize the symptoms and know when to seek medical attention.

The first line of defense against head injuries is to ski responsibly - that means always ski under control. When you stop, make sure you're in a spot where others can see you, and stay away from trees, unless you really know what you're doing - they're unforgiving.

The second line of defense is to wear a helmet.  Can wearing a helmet make a difference? You bet it can.  A helmet will reduce the risk of head injury, but it won't make you invincible.  What we've learned about wearing helmets is that it will decrease your risk of head injury by 20 percent to 50 percent, it can mean the difference between a major head injury and a minor head injury, and it can mean the difference between a minor head injury and no injury at all.

Do helmets have limitations? Of course they do. If you're barreling down the mountain at 60 mph like Franz Klammer, injuries you sustain in a fall may overwhelm the protective capabilities of a helmet.

The average recreational ski or snowboarding helmet is designed to provide protection when skiing at speeds of less than 15 mph.  Because it is common for skiers and boarders to reach speeds of 25-40 mph on some intermediate trails, recognize that, at these speeds, a helmet may not provide complete protection.  For a helmet to provide proper protection at those speeds, it would have to be 7 inches thick, 20 inches wide, and weigh 10 pounds … and that's simply unrealistic.

The bottom line is that although helmets cannot provide ultimate protection for all falls, they will prevent or lessen the degree of head trauma for most falls - and because there's no good reason not to wear a helmet, just strap one on.

In the past, one of the biggest reasons not to wear a helmet was that it was perceived as being "uncool."  Today that is just the opposite; you look "cooler" with a helmet.

More and more Americans are wearing helmets when they ski or snowboard.  In some ways, it took a tragedy to bring the importance of wearing helmets to the forefront of the American public.  In 1998, within days of each other, Michael Kennedy and Sonny Bono both died as a result of head injuries they sustained while skiing. Both of them hit trees. Neither of them were was wearing a helmet.

These events revolutionized the ski helmet industry.  Ten years ago, virtually nobody wore ski helmets; five years ago, 25 percent of skiers wore helmets. Today, more than 60 percent of skiers and boarders wear helmets, including 80 percent to 90 percent of children.  The most underrepresented population continues to be 18-24-year-olds, who wear helmets only 48 percent of the time.

In order to get the most protection from your helmet, it's important that it fit properly.  First of all, never use a bicycle helmet or skateboarding helmet; they are not designed for skiing or snowboarding. Your helmet should be snug, but not tight. As parents, many of us "hand down" clothing and athletic equipment to our younger children; use caution when doing this with helmets, as a helmet that is too big won't provide proper protection. A helmet isn't something that your child should "grow into." Finally ensure that your chinstrap is always fastened securely.

As recently as 2011, 46 states in this country had motorcycle helmet laws, 37 states had bicycle helmet laws, and not a single state had any law mandating the use of helmets on the slopes. Our European colleagues have been ahead of us in this regard - in 2009, Austria mandated that all children less than 14 years old must wear helmets.

But things are changing; in April 2011, Gov. Chris Christie of New Jersey signed a bill that mandates that children less than 18 years old must wear helmets while skiing or snowboarding or their parents will face fines that range from $25-$50.  Similar legislation is pending in New York.

Finally, the last line of defense against head injuries on the mountain is to be able to promptly recognize an injury when it occurs, so treatment is not delayed.  There is no better story to tell than that of film star Natasha Richardson, to reinforce the importance of this.

In 2009, Natasha Richardson was skiing in Canada and fell on a beginner trail. She hit her head. She was not wearing a helmet.  Initially she felt fine; she returned to her hotel room, but developed a headache. By the time she eventually sought medical attention, she lapsed into a coma and ultimately died.  Neurosurgeons have speculated that she might be alive today if:  1) she had been wearing a helmet, and 2) her symptoms had been recognized earlier.

This tragedy underscored the importance of recognizing the symptoms of head injury before it's too late.  These symptoms include being knocked unconscious, drowsiness, confusion, garbled speech, inability to walk, vomiting, or headache.  Remember that these symptoms might occur immediately, or may not present for hours after the event.

Natasha Richardson's tragedy, like that of Michael Kennedy and Sonny Bono, woke up the public to the importance of safety on the slopes.  In the year following Richardson's death, helmet sales in the United States soared 23 percent, and emergency room physicians in Canada reported a 30 percent increase in evaluations for head trauma - not because there were more injuries, but because there was now a heightened awareness of the symptoms of a potential head injury.

Skiing and snowboarding are great sports … in fact they are among my family's favorites.  As you can see from the above, with a few small safety precautions, everyone can have fun of the slopes.  See you on the mountain.

Dr. Christopher Magovern is an ABC News contributor and a cardiac surgeon at Morristown Medical Center in Morristown, N.J.