Oxygen
Of all the health
recommendations one could make, the best might be to recommend adequate oxygenation to our bodies. Although there are free divers who can survive 10 minutes underwater without oxygen, most of us would have trouble staying alive after 3 minutes without oxygen. Luckily, our ambient atmosphere is about 21% oxygen and it is readily available to us whenever we need it. We seem to get an adequate amount too because if we check our blood through a pulse oximeter, we will see
that for most of us it regularly reads that our blood is 95-99% saturated with oxygen.