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.
If you are working out strenuously, they may be higher because your body requires more oxygen to function properly. Understanding your blood oxygen levels when you are at rest is something that you need to do if you want to make the most of the oxygen that's entering your body. Normal blood oxygen levels for the average American is about 90 to 100 percent oxygen saturation. This means that your body is getting enough oxygen if your levels fall somewhere in this range. Your body is getting the oxygen it needs to perform basic functions and your internal organs are likely performing at their best when you keep your blood oxygen levels this high.