His predecessor was the first pope to retire due to deteriorating health — a condition no doubt exacerbated by frequent world travel and a demanding schedule. Yet at age 76, Pope Francis arrives at the Vatican with his own medical history. Specifically, the new leader of the Catholic Church had one of his lungs removed as a teen, likely because of an infection.
Medical experts said the pope's condition shouldn't stand in the way of his ability to manage one of the world's largest nonprofit organizations — as long as he can guard against a serious case of pneumonia or influenza. Even with one lung missing, his pulmonary function is still 60 percent to 70 percent that of a person with two lungs. "People who have spent their entire life living with one lung usually accommodate to it extremely well," said Dr. Richard Shemin, chief of cardiac and thoracic surgery at Ronald Reagan UCLA Medical Center in Los Angeles. "That's assuming they don't smoke and do everything they can to not have environmental factors destroy their good lung."
Today, the primary cause of lung removal is lung cancer. But decades ago, before the availability of powerful antibiotics, lung removal would have been a radical way of treating infection brought on by severe tuberculosis or pneumonia.
Shemin said that in cases in which a lung has been removed, function of the residual lung is increased. "Two lungs are not required for life," he said.
Doctors measure lung function according to the amount of air a person can expel from their lungs in one second.
Healthy individuals with two lungs will blow out roughly 4 liters of air. A healthy person with one lung will blow between 2.5 and 2.75 liters, said Dr. John Belperio, a professor of pulmonary and critical care at the David Geffen School of Medicine at the University of California at Los Angeles.
Even individuals who blow out just 1.5 liters of air can sustain life for a long time, he said.
"Typically, it does not impair a person's life, really, in any way," Belperio said. "They live essentially as long as a normal person would live. Typically, they can exercise, depending on their conditioning, pretty similar to a normal person. So they don't really have any true physical limitations."
Even with a demanding schedule and frequent travel, a single lung is unlikely to limit a person's ability to work, experts said.