"In 1954, Wells began a long-term experiment to demonstrate that tuberculosis could be transmitted through air. At the VA Hospital in Baltimore, collaborating with Riley, John Barnwell, and Cretyl C. Mills, he built a chamber for 150 guinea pigs to be exposed to air from infectious patients in a nearby TB ward. After two years, they found that an average of three guinea pigs a month were indeed infected. Although this was exactly the rate Wells had predicted, skeptics complained that other methods of transmission (such as the animals' food and water) had not been conclusively ruled out. A second long-term study was begun, this time with a second chamber for an additional 150 guinea pigs, whose air was sterilized with UVGI. The animals in the second room did not become ill, proving that the only transmission vector in the first room was the air from the tuberculosis ward. The study was completed in 1961, and published in 1962, though Wells did not see the final paper.^{[1]"(Wikipedia article William F. Wells, accessed 2-2021)}