He was Gifford Lecturer in the University of Glasgow, Fellow of New College, Oxford, and Honorary Professor of the University of Birmingham. Haldane received numerous honorary degrees. He was also President of the English Institution of Mining Engineers, a Companion of Honor of the British Court, a Fellow of the Royal Society, a member of the Royal College of Physicians and of the Royal Society of Medicine.
Sir Henry Newbolt wrote a poem called "For J. S. Haldane", published in his anthology "A Perpetual Memory and other Poems" in 1939.
Haldane was an international authority on ether and respiration and the inventor of the gas-mask during World War I. (The Sciences and Philosophy: Gifford Lectures, University of Glasgow, 1927–28 by J.S. Haldane, Doubleday, Doran and Co., Inc., Garden City, NY, 1929)
John Scott Haldane helped find out how to determine the regulation of breathing and discovered the Haldane effect in hemoglobin. He was the founder of The Journal of Hygiene. In 1907 Haldane made a decompression apparatus to help make deep-sea divers safer and produced the first decompression tables after extensive experiments with animals. He was also an authority on the effects of pulmonary diseases, such as silicosis caused by inhaling silica dust.
He investigated the principle of action of many different gases. He investigated numerous mining disasters, especially the toxic gases which killed most miners after firedamp and coal dust explosions. The toxic mixtures of gases found in mines included afterdamp, blackdamp and whitedamp. He identified carbon monoxide as the lethal constituent of afterdamp, the gas created by combustion, after examining many bodies of miners killed in pit explosions. Their skin was coloured cherry-pink from carboxyhaemoglobin, the stable compound formed in the blood by reaction with the gas. It effectively displaces oxygen, and so the victim dies of asphyxia. As a result of his research, he was able to design respirators for rescue workers. He tested the effect of carbon monoxide on his own body in a closed chamber, describing the results of his slow poisoning. In the late 1890s, he introduced the use of small mammals for miners to detect dangerous levels of carbon monoxide underground, either white mice or canaries. With a faster metabolism, they showed the effects of poisoning before gas levels became critical for the workers, and so gave an early warning of the problem. The canary in British pits was replaced in 1986 by the electronic gas detector.
Haldane pioneered study of the reaction of the body to low air pressures, such as that experienced at high altitudes. He led an expedition to Pike's Peak in 1913, which examined the effect of low atmospheric pressure on respiration.
In addition to his work on mine atmospheres, he investigated the air in enclosed spaces such as wells and sewers. One surprising result of his analysis of the air in the sewers beneath the House of Commons was to show that the level of bacterial contamination was relatively low. During this research, he investigated fatalities of workmen in a sewer, and showed that hydrogen sulfide gas was the culprit.