At 7:30 ee started balancing 298-04-3 grate discharge dust collector near kiln. The ee began to experience a headache, nausea and some disorientation around 8:00am. The temperature in the area was around 140F. They took a break at 8:30am and ee went to the office to cool off. After 1/2 hr the ee decided to seek medical treatment and received an IV treatment at Med Ctr