 Researchers know that heat is hurting and even killing workers, like postal worker Eugene Gates Jr., who died from heat stroke while delivering mail last summer in Dallas. And the Department of Labor estimates that there have been about 34,000 injuries caused by heat in the past 10 years alone, and probably many more. Worker advocates, they've been asking for federal heat rules since the 1970s, but climate change is now making summers hotter, and that's really increasing the urgency here.