Largely as the result of the enthusiastic endorsement of Northrup1 of New York in a series of papers on the subject, published between 1904 and 1906, the cold-air treatment of pneumonia has been more or less completely adopted by most pediatricians and by many practitioners. No very satisfactory explanation for the supposedly beneficial results of this method of treatment was advanced, however, in the beginning.
Howland and Hoobler,2 writing in 1912, stated that it was apparent that children seriously ill with pneumonia might have a blood pressure somewhat below what might be expected at their age, and that the symptoms of the death of children from pneumonia were those of vasomotor failure. They found that the effect of cold, fresh air in patients with active pneumonia was always to produce a rise in blood pressure. Removal to a warm (65 F.) room produced a fall in blood pressure.
MORSE JL, HASSMAN DM. THE EFFECT OF COLD AIR ON THE BLOOD PRESSURE IN PNEUMONIA IN CHILDHOOD. Am J Dis Child. 1916;XII(5):445-458. doi:10.1001/archpedi.1916.04110170023002