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.
Get help from a doctor now âº. Oxygen level....: The oxygen saturation, or pulse oximetry, should be in the 90's normally. Any value of less than 88% on room air qualifies a patient for supplemental oxygen therapy. So, an oxygen saturation in the 80s is not normal.Your doctor will need to find out why your oxygen level is low and provide treatment.et help from a doctor now âº. Oxygen level....: The oxygen saturation, or pulse oximetry, should be in the 90's normally. Any value of less than 88% on room air qualifies a patient for supplemental oxygen therapy. So, an oxygen saturation in the 80s is not normal.