Before that, in 2006, climber Lincoln Hall, who was left for dead on Everest on May 25, 2006, managed to survive. Lack of oxygen in his blood made it easier for him to get frostbite. He also had headaches, nausea, vomiting and hallucinations. He said later this was caused by cerebral edema – or swelling of the brain. This is caused at high altitude when blood leaks into the brain itself and that can kill a person if the brain becomes too compressed. Hall was left for dead when his breathing and heartbeat stopped. He was found the next morning by a team of four led by U.S. climber Daniel Mazur. Hall was sitting cross-legged near a ten-thousand foot cliff's edge, without his gloves, hat, or oxygen, with his climbing suit unzipped. Mazur later reported that Hall seemed lucid, and his first words were, "I imagine you're surprised to see me here." A massive rescue operation was assembled, and Hall was rescued. He survived for an additional seven years, speaking and writing books about his experiences on Everest, before his death in 2012 from mesothelioma.