Effect

Atmospheric Oxygen (dry air, sea level)

Concentration %

Pressure mm Hg

no symptoms

16 to 20.9

122 to 159

increased heart and breathing rate, some lack of coordination, increased breathing volume, impaired attention and thinking

16

122

abnormal fatigue upon exertion, emotional upset, faulty coordination, impaired judgment

14

106

very poor judgment and coordination, impaired respiration that may cause permanent heart damage, nausea and vomiting

12

91

nausea, vomiting, lethargic movements, perhaps unconsciousness, inability to perform vigorous movement or loss of all movement, unconsciousness followed by death

< 10

< 76

convulsions, shortness of breath, cardiac standstill, spasmatic breathing, death in minutes

< 6

< 46

unconsciousness after one or two breaths

< 4

< 30