Title: What Are the Limits of Human Survival? | Human Tolerance | Live Science
Headings: What Are the Limits of Human Survival?
What Are the Limits of Human Survival?
How long can we stay awake?
How much radiation can we absorb?
How much can we accelerate?
What environmental changes can we handle?

Content: Individuals vary greatly in how well they tolerate departures from normal atmospheric conditions, whether these are changes in temperature, pressure or oxygen content of the air. Bounds of survival also depend on how slowly environmental changes set in, because the body can gradually adjust its oxygen usage and metabolism in response to external conditions. But some rough estimates of our breaking points can be made. Most humans will suffer hyperthermia after 10 minutes in extremely humid, 140-degree-Fahrenheit (60-degrees-Celsius) heat. Death by cold is harder to delimit. A person usually expires when their body temperature drops to 70 degrees F (21 degrees C), but how long this takes to happen depends on how "used to the cold" a person is, and whether a mysterious, latent form of hibernation sets in, which has been known to happen. The boundaries of survival are better established for long-term comfort. According to a 1958 NASA report, people can live indefinitely in environments that range between roughly 40 degrees F and 95 degrees F (4 and 35 degrees C), if the latter temperature occurs at no more than 50 percent relative humidity. The maximum temperature pushes upward when it's less humid, because lower water content in the air makes it easier to sweat, and thus, keep cool. [ Infographic: