Christian McMillen is a historian and associate dean at the University of Virginia and the author of “Discovering Tuberculosis.” “It was a relatively common notion that air – whether it’s altitude, winter air, desert air, or what have you – was a good solution for tuberculosis,” he says. “Sometimes it did help. But there was a kind of mistake in correlation with causation. TB is contagious, so in this case, my guess is that you take five people with TB, and five people without TB, and put them together in a cave, and you’re going to wind up with 10 people who have TB.”