Two summers ago, 35-year-old Timothy Barber started a new job with a contractor on a bridge project, sorting bolts in upstate Geneseo, N.Y. The temperature outdoors was in the 90s and at the end of his day Barber's father did not think he looked well. The next day he collapsed on the jobsite at the end of his shift, dying before reaching the hospital. 

The cause was hyperthermia, or high body temperature.