Single lung not likely to hinder new pope, doc says The world's newest pope lost a lung to an infection as a teenager, but medical experts say that likely hasn't limited the 76-year-old pontiff's energy or actions in the past -- and shouldn't stop him in the future. Cardinal Jorge Mario Bergoglio of Buenos Aires, who will be known as Pope Francis, appears to be fit and lean and should have lung capacity that is nearly normal, said Dr. Zab Mosenifar, a lung expert at Cedars Sinai Medical Center in Los Angeles. "Without seeing and testing him, I would comfortably say he functions at 85 to 90 percent capacity of someone his age that has both lungs and hasn't taken such good care of himself," Mosenifar said. It just didn't faze me. The new pope likely lost his lung more than 50 years ago, at a time when severe fungal infections or pneumonia were treated with surgery because antibiotics weren't widely available. But his single lung likely grew and expanded to near-normal capacity within a year or two, said Mosenifar, who is co-medical director of the Women's Guild Lung Institute. Human lungs have excess capacity, which is why doctors typically use only one lung in transplants. There are likely 30,000 to 40,000 transplant patients in the U.S. living with one lung, and thousands more who lost a lung to disease or trauma, Mosenifar said. Many single-lung patients go on to have not only normal lives, but active ones, said Dr. Edward Salerno, a pulmonologist with Hartford Hospital in Hartford, Conn. "They can exercise and not feel any dysfunction," he said.