Oxypritol is a chemical compound developed to adapt to varying atmospheres.
During the early stages of colonization, many Terran worlds needed to be terraformed before more settlers could be transported. Early explorers needed to take regular amounts of Oxypritol to prevent being suffocated or poisoned by the different atmospheres each target world had (Star Trek: Tri-ox compound and Trioxin). Common side effects included minor headaches and shortness of breath that wear off after two or three hours.
Currently, it is essential for all travelers going to other planets or miners digging in unexplored mines.