Ang Rita Sherpa, 72, who earned global fame by climbing the world's highest mountain, Mount Everest, 10 times without the use of supplemental oxygen, died Sept. 21 in Kathmandu.

He had been suffering in recent years from multiple lung and brain ailments that colleagues say could have developed from his years of climbing high altitudes without bottled oxygen.

Most climbers use supplemental oxygen when ascending peaks higher than 8,000 meters, an altitude mountaineers call the "death zone" because the air is so thin that the human body begins to shut down. Early in his career as a porter, and later as a mountain guide, Ang Rita noticed that he never felt the need for supplemental oxygen, even as he carried bottles of it for other mountaineers. He didn't use it during his first ascent of Everest in 1983 or on his subsequent nine ascents, the last of which was in 1996.

In his only winter expedition on Everest, in 1987-88, he and a Korean climber lost their way just below the summit in bad weather conditions and spent the whole night doing aerobic exercises to stay warm.

Ang Rita holds the Guinness World Record for most climbs of Everest without bottled oxygen, a record that remains unequaled. (Another Sherpa, Kami Rita, holds the record for most total ascents of Everest, having done it 24 times, but he was known to use bottled oxygen.)

The Nepalese government honored Ang Rita with several awards, most notably the Order of Tri Shakti Patta First Class in 1990.

"His demise is an irreparable loss to the country's climbing industry," President Bidya Devi Bhandari of Nepal wrote on Twitter.

Ang Rita Sherpa was born in 1948 in Yillajung, a tiny village near Thame in the Everest region of Nepal. His mother, Chhokki Sherpa, and his father, Aayala Sherpa, were farmers. Ang Rita never received a formal education (no school was established in the Everest region until 1961, when Edmund Hillary, the first mountaineer to reach the summit of Everest, built one in Khumjung).

He learned the Nepali alphabet on his own and could barely write his name.

Ang Rita spent his childhood days in the high pastures grazing yaks, growing potatoes and carrying commodities from nearby markets. He became a porter when he was 15 and quickly gained a reputation for his agility, ultimately earning the nickname Snow Leopard.

Although he was raised under the shadow of Mount Everest, his first job as a porter was to climb Dhaulagiri, a Himalayan massif that includes the world's seventh-highest mountain, for which he had no shoes or equipment.

In addition to climbing Everest 10 times, Ang Rita climbed Dhaulagiri four times, as well as the Himalayan peak Cho Oyu — also four times — and Kanchenjunga, the third-highest peak, once. He didn't use supplemental oxygen on any of these climbs.

Dr. Rebecca Shadowen (pronounced SHAD-oh-en), 62, a specialist in infectious diseases and health care epidemiology who began treating coronavirus patients in March, died of the disease in September.

In March, the Medical Center at Bowling Green, Ky., had just begun to get cases and the World Health Organization had declared COVID-19 a pandemic.

On March 13, Dr. Shadowen was way ahead of the game, posting a pro-mask message on Facebook: "If you could save the life of another person without harming your own, would you?"

The Centers for Disease Control and Prevention made a formal recommendation about mask-wearing on April 3, and the subject quickly became a partisan issue.

Dennis Chaney, a Medical Center colleague, recalled in an interview with NBC that Shadowen was always reminding others, "Look, folks, this isn't politics; it's science."

Shadowen died of COVID at the Medical Center on Sept. 11, the hospital said. She had been ill for four months, but had continued to attend meetings of the Bowling Green-Warren County Coronavirus Workgroup from her hospital bed.

Shadowen had been on the hospital staff for 31 years and had specialized earlier in treating people with HIV/AIDS and Lyme disease. By the time of her diagnosis in May, there were at least 750 confirmed cases of the coronavirus in Warren County, which includes Bowling Green, and she was running COVID treatment trials.

But she and her family said they felt certain that she had not been infected at work, where precautionary measures were strict.

The likeliest source was a home health care worker (who was infected but didn't know it) tending to her mother-in-law, who was the first family member to become ill.

Her husband, Dr. David Shadowen, a retired internal medicine specialist and endocrinologist, and their daughter, Kathryn, also contracted the virus and experienced mild symptoms. The Shadowens' son, Jesse, did not.

All three survive her.

Rebecca Dawn Hunt was born in Louisville on April 4, 1958, the daughter of Edwin Audley Hunt and Audrey June (Barrow) Hunt.

She met David Shadowen when both were students at Western Kentucky University in Bowling Green. They married in 1981, after their first year at the University of Louisville School of Medicine. Rebecca Shadowen did her residency at the University of Missouri-Kansas City and further study at the Medical University of South Carolina in Charleston.

When Anderson Cooper interviewed the family on his CNN podcast, which was released Sept. 21, he voiced his admiration for Shadowen's assistance to others despite putting herself at serious risk.

"She was always like that," daughter Kathryn Shadowen said.