Doing what he loved nearly killed Jon Dana.
Dana, now 36, a lifelong skier, drove all night from his farm in Richmond, Mo., to Colorado's Winter Park Resort a few years ago. Then he hit the slopes just as he always did.
By Day 3, after developing a cough he dismissed as a cold symptom, Dana had trouble breathing, his lips turned blue and he had bad headaches. The diagnosis: a life-threatening case of high-altitude pulmonary edema, or fluid in the lungs, one of several ailments that can strike mountain visitors.
''It was a scary thing,'' Dana said.
Few mountain visitors are at risk of getting as sick as Dana. But one out of four, experts say, might develop the headaches and nausea that signal acute mountain sickness, commonly known as altitude sickness.
Most sufferers will feel better in a day or so with rest, over-the-counter drugs such as ibuprofen, and time, the ultimate remedy, as their bodies adjust to the altitude. An unfortunate few might remain ill longer or, very rarely, develop pulmonary or cerebral edema, a fluid build-up in the lungs or brain that can prove fatal.
Who will get sick is hard to predict. What we do know is that the lower barometric pressure at high altitudes causes people to get less oxygen with each breath, triggering various responses. Typically, you breathe faster, urinate more and sleep fitfully. All pretty normal, experts say.
How abnormal symptoms such as headaches develop is disputed.
''We don't entirely understand why cerebral edema occurs where it occurs,'' said Dr. John Severinghaus, retired professor of anesthesiology at the University of California, San Francisco and a top authority on mountain sickness.
Severinghaus and several other experts agreed on two things: The surest cure for altitude sickness is to descend. And you shouldn't go higher until symptoms disappear. Beyond that, here are myths that could get you in trouble:
• You'll be fine below 10,000 feet. In fact, a fourth of people visiting Rocky Mountain resorts from 6,300 to 9,700 feet up developed acute mountain sickness, according to a 1993 study of more than 3,000 conference attendees. The elevation of Granby, Colo., where Dana slept, is about 8,000 feet (although some local ski runs start above 12,000 feet).
How fast you ascend and where you sleep are more important than elevation, said Dr. Thomas Dietz, who ran a hospital near Mount Everest Base Camp in the 1990s. Spend at least one night below 10,000 feet and then sleep no more than 1,000 feet higher each night, said Dietz, now an emergency physician in Hood River, Ore.
• The physically fit don't get sick. ''Absolutely false,'' Dietz said. And dangerous too, because athletic people who believe this myth might ascend despite symptoms. Obviously, people with lung or heart disease might be at risk. And in the 1993 study, visitors who lived below 3,000 feet or had previous bouts of altitude sickness showed symptoms more often. But there's little consensus about risk factors.
• A headache at altitude is normal. It may be common, but that doesn't mean it's normal, Severinghaus said. An altitude headache might result from mild cerebral edema; in other words, your brain might be swelling. Typically, the headache lessens as you acclimate, but if it doesn't or gets worse, you should seek medical advice.
• After the first day, you'll be OK. Acute mountain sickness often strikes within 12 hours after you arrive at high altitude, but it might hit later. In rare cases, symptoms linger for weeks.
• Consuming water prevents altitude sickness. It counters dehydration, which also can cause a headache and more severe symptoms, but there's no evidence that it forestalls mountain sickness, experts said.
Prescription medications such as acetazolamide (Diamox) and dexamethasone (Decadron) often help. But the best antidote is awareness.
''There are a lot of people getting sick without knowing what it is,'' said Dr. Peter Hackett, director of the Institute for Altitude Medicine in Telluride, Colo.
After his harrowing episode, Dana says, 'The main thing I would tell people is: `Listen to your body.' ''
