Sanatoria and Sunlight, Dr R A Hobday.
In architectural terms it is often difficult to distinguish between open-air sanatoria for pulmonary tuberculosis, and heliotherapy clinics for surgical tuberculosis, as both were oriented for sunlight: but for different reasons. Open-air sanatoria were designed to admit sunlight in an attempt to kill bacteria and prevent the cross- and re-infection of patients. In 1877 Arthur Downes and T P Blunt had shown that light had a bactericidal effect and in 1882 the German bacteriologist Robert Koch had discovered the tubercle bacillus (Mycobacterium tuberculosis) and proved that it caused the disease. In 1890 Koch carried out further experiments which showed that sunlight was lethal to the bacillus. Once it was recognized that the bacilli were present in the expectorated mucus or phlegm of infected individuals, and that dried tuberculous sputum or tuberculous dust could infect people who were in a condition to contract the disease, designers of sanatoria were encouraged to exploit the germicidal properties of sunlight:
Although sanatoria were designed to be sunlit, facilities for sunbathing were not normally provided because heliotherapy did not form part of the open-air regime for pulmonary tuberculosis. Photographs of open-air sanatoria often show patients, in their beds, on balconies or verandas. They are covered by bedclothes and there is no evidence of any attempt to expose their bodies to direct sunlight. As an article in the Lancet of 1923 noted:
Institutions for the heliotherapy of surgical tuberculosis were, on the other hand, arranged so that sunlight could be clinically applied with the specific objective of tanning the patients to facilitate a cure. The physicians who carried out some of the formative work in this field were also active, directly or indirectly, in the design of such institutions.
From, Dr R A Hobday, Medical History, 1997, 42: 455-472.