http://www.bt.cdc.gov/disasters/extremeheat/heat_guide.asp
This document also available in Spanish
National Center for Environmental Health, Centers for Disease Control and Prevention
Summertime activity, whether on the playing field or the construction site, must be balanced with measures that aid the body's cooling mechanisms and prevent heat-related illness. This pamphlet tells how you can prevent, recognize, and cope with heat-related health problems.