I have O2 or oxygen heart monitor it checks your heart rate and oxygen levels in your blood stream. Healthy individual should have blood O2 level of 95% and above. I bought it with free diving and breath holding exercises in mind.
Free diving is quite a big sport these days some free diving competitions use a shot line and a sledge arrangement were the free or breath holder diver holds on to the sledge to take him to depth. He or she must equalise their ears constantly on the way down and on the way back up.
It’s rather dangerous sport as you have propensity to black out near the surface due to an excess of carbon dioxide in the blood. They have to have scuba support divers just in case the free diver blacks out!
Women make excellent free divers but most use mediation techniques to get into the psychological zone. They train as well with breath holding techniques to maximise their lung capacity and they’re extremely fit with very low heart rates. That said it’s still quite dangerous sport. I once worked with a guy who was an active underwater free diver spear fisherman and he use sit in his chair with head back and do practice breath holding exercises on daily basis. The head back in his chair was in case he blacked out.
My brother in law recently had bad doze of Covid and he was hospitalised due to low blood oxygen levels they were well below 90%. After he was released from hospital he was on therapeutic oxygen for about 3 months possibly longer due to low oxygen levels in his blood stream.
Without oxygen we’d all die! Oxygen wasn’t in the earths atmosphere billions of years ago and now we have 21% oxygen in the air we breath.
When I was High Altitude Free fall military parachutist we had to go into RAF decompression chamber to replicate operating at high altitude with low oxygen levels and perform simple takeaway arithmetic to see how impaired we were mentally with low oxygen levels which is called hypoxia.
Also when I was a little younger I did technical scuba diver course your on higher levels of oxygen when decompressing to remove nitrogen from your blood and tissues. On high levels of oxygen the opposite is true and at a 100% concentrations under pressure at 2 atmospheres or 30psi this causes oxygen toxicity. This affects the nervous system and you go into convulsions in an underwater diving situation and can be fatal. Hence why there are lots fatalities with deep sea technical diving.
Where did the oxygen come from originally was it complete freak and accident of nature!
We can thank a Bactria for that what sort of bacteria was it? Cyanobacteria. Cyano meaning blue green algae how could such an innocuous algae produce life giving oxygen when prior to Cyanobacteria most basic forms of live were anaerobic. Or non oxygen requiring life forms.
Let’s go back to Cyanobacteria how did it form in the first place. The more you look at the chemistry of earth the more you realise the absolute miraculous nature of life!
So how did earth end up with 21% oxygen in the present day atmosphere? answer is tiny organisms known as cyanobacteria, or blue-green algae. These microbes conduct photosynthesis using sunshine, water and carbon dioxide to produce carbohydrates and, yes, oxygen. In fact, all the plants on Earth incorporate symbiotic cyanobacteria (known as chloroplasts a green plant that contains chlorophyl ) to do their photosynthesis for them each day.
But roughly 2.45 billion years ago, the isotopic ratio of sulfur transformed, indicating that for the first time oxygen was becoming a significant component of Earth’s atmosphere. At roughly the same time (and for eons thereafter), oxidized iron began to appear in ancient soils and bands of iron were deposited on the seafloor, a product of reactions with oxygen in the seawater.
Oxygen was first produced somewhere around 2.7 billion to 2.8 billon years ago. It took up residence in atmosphere around 2.45 billion years ago. It looks as if there’s a significant time interval between the appearance of oxygen-producing organisms and the actual oxygenation of the atmosphere.
scientists refer to as the Great Oxidation Event, but mysteries remain. What occurred 2.45 billion years ago that enabled Cyanobacteria to take over. What were oxygen levels at that time? Why did it take another one billion years—dubbed the “boring billion” by scientists—for oxygen levels to rise high enough to enable the evolution of animals?
No one has come up with a rock-solid test to determine the precise oxygen content of the atmosphere at any given time from the geologic record. But one thing is clear—the origins of oxygen in Earth’s atmosphere derive from one thing: life.
One of my favourite books, which I read a few years ago, was written by group of eminent scientist called “Chance”
Basically it’s premise was; life is like roll of the dice. What’s the chance or odds of winning the lottery jackpot? Evidently they’re mind boggling at 14 million to one. Why do we think we are in with a chance of winning the jackpot? Really that’s how I feel about life on Earth, its was one in billion dollar jackpot that by sheer chance planet Earth happen to produce such a complex web of life.
That’s why I always chuckle to myself when we think life is everywhere in the universe as if life was a normal occurrence.