Yet humans are rarely attacked by a shark, while millions of sharks are killed by humans. Some populations of shark species, such as the shortspine spurdog, may have dropped by 95 percent. The sharksâ population decline has a ripple effect â throwing entire marine ecosystems out of balance.
Quick Answer. A normal blood oxygen level during sleep is approximately 94 to 98 percent, according to Sleep Apnea Guide. Levels below 90 percent oxygen saturation are dangerous to the human body. The human brain can only survive four minutes without oxygen before cell death occurs.
The Harvard link I've provided explains that blood oxygen saturation levels are normal at 95%-100%. This is what you would expect a healthy adult to be.hat is considered a normal blood oxygen saturation level for a non-smoker how can this be affected by smoking and at what range is blood oxygen saturation considered impaired Resources appreciated.?