EE was lubricating rotary kiln equipment. Around 6:30 he had dinner, then around 8:30 ee & co-worker met with their supervisor in the control room. He said he felt hot, so he took off one of the shirts he had on & stood outside of the control room to cool off. His supervisor went with him to the breakroom to relax for a while. He started having chest pain, another ee called 911.