Hiking equipment
According to Tom Brown, the basic plan for survival is in the order of shelter (including clothing), water, fire, and food. Cody Lundin writes about the "Rule of 3s"; this relates to human survival without basics: three minutes without air, three hours without shelter, three days without water, or three weeks without food.
Health effects of radon
The effects of radon, if found in food or drinking water, are unknown. Following ingestion of radon dissolved in water, the biological half-life for removal of radon from the body ranges from 30 to 70 minutes. More than 90% of the absorbed radon is eliminated by exhalation within 100 minutes, By 600 minutes, only 1% of the absorbed amount remains in the body.