Boulder photographer airlifted off Mount Everest

A Boulder photographer shooting for National Geographic magazine had to be rescued by helicopter from Mount Everest on Saturday after he suffered what appeared to be a pulmonary embolism, according to National Geographic News.

Cory Richards was part of a National Geographic and North Face expedition to commemorate the 50th anniversary of the first U.S. ascent of Everest. Richards' medical problems were reported when the team was at about 23,000 feet and he descended to a camp at 17,600 feet, the NGS reported.

Camp doctors gave him blood thinners and called for the evacuation.

He was taken to a medical facility in Lukla, Nepal, and then to to Kathmandu on Sunday, NGS reported. He remained hospitalized Monday.

Richards was named the 2012 Adventurer of the Year by National Geographic and was the first American to summit a peak higher than 8,000 meters - Pakistan's Gasherbrum II - in winter. The footage he took of his climb became the film "Cold," which won grand prize at the Boulder Banff Mountain Film Festival in 2011.

In a profile of the team members on the National Geographic website, Richards wrote:

"This expedition is a culmination of my career as a photographer and climber. It is the realization of a partnership, friendship, and mentorship that reaches beyond words."