History of measuring O2 and CO2 responses.

Quantitative analysis of the chemical interactions of CO2 and O2 on ventilation from early 20th century to the present start with the amazingly steep CO2 response found by Haldane and his pupils, proceed through discovery of the prime role of the H+ ion and the discovery of carotid body chemoreception. The interaction of central and peripheral drives and changes with time and acute and chronic altitude exposure are still under investigation.