This article was a finalist for the 2010 National Magazine Awards in the personal service category.

As the highest state in the Lower 48, Colorado sells altitude. It's what we've got that others want—which is why people come from all over to ski down our mountains, camp near our alpine lakes, and climb our fourteeners. Not that we blame them; we dig our state's God-given natural beauty and well-endowed topography, too. But here's the rub: There are risks associated with living, playing, or vacationing at altitude. Strange thing is, most people—and way too many Coloradans—don't realize just how much we're all affected by our extraordinarily thin air.

Into Thin Air
Demystifying Acute Mountain Sickness.

Slope Sick
Calculating the cost of altitude illness.

Got Oxygen?
A low O2 environment forces the body to try to adjust. Here's what happens when you head for the hills.

Study groups
Colorado's cutting-edge research aims to lower the risk of altitude sickness.