John Scott Haldane was born in 1860 in Edinburgh, Scotland. The Haldane family was among the city's notable citizens. He studied medicine at the University of Edinburgh, where he graduated in 1884.
After a brief appointment at Queen's College in Dundee, he moved to Oxford. He specialized in respiratory physiology and discovered that the concentration of carbon dioxide in the blood, rather than oxygen concentration, served as the primary regulatory mechanism for breathing. Haldane studied the effects of altitude and depth on breathing and blood gas concentrations. Through his compartmental theory, he developed decompression tables, which, among other uses, enabled the safe recovery of gold from the *Lusitania* between 1917 and 1924. He also made significant contributions to the theoretical understanding of maximum ascent rates for scuba divers. Furthermore, Haldane significantly improved safety for miners by demonstrating the toxic effects of carbon monoxide and introducing various safety tools.
He founded the *Journal of Hygiene*, where he published his first decompression tables in 1908. Additionally, he authored works such as *Organism and Environment* (1917), *Respiration* (1922), and *The Philosophy of a Biologist* (1936).
In 1936, he traveled to Persia to study the effects of heatstroke on oil workers. However, upon returning to cold Oxford, he contracted pneumonia. He passed away later that year as a result of the illness.
