This article is from the Aerobics Fitness FAQ, by oaktree@shell.urjet.net (Robles) with numerous contributions by others.
These curves approximate the figure in the 1993 American Red Cross
Standard First Aid manual.
HOT: {93F (34 C), 20% humidity}, {87 F(31 C), 50%}, {82 F(28 C),100%}
Sunstroke, heat cramps, or heat exhaustion possible with prolonged
exposure/exercise
VERY HOT: {105F(41C), 20%}, {92F(34C), 60%}, {87F(31C), 100%}
Heat cramps or heat exhaustion likely
EXTREMELY HOT: {120F (49C), 20%}, {108F(43C), 40%}, {91F(33C), 100%}
Heat Stroke or sun stroke imminent
Reference, 1993 American Red Cross Standard First Aid Manual
 
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