When Oregon temperatures climb into the 90s and even the 100s, people are not acclimated to the heat and that can cause serious problems.  Oregon OSHA officials say workers run the risk of developing a heat-related illness when physical exertion is combined with high temperatures and high humidity.  Employers and workers should be familiar with some of the common signs of heat exhaustion.  State officials say a person overcome with heat exhaustion will still sweat but may experience extreme fatigue, nausea, lightheadedness, or a headache.  The illness could progress to heat stroke, and possibly even death.  From 2007 through 2011, 38 people received benefits through Oregon's Workers' Compensation System for heat-related illnesses.