A chemical plant maintenance worker suddenly collapses while cleaning the inside of a storage tank. Not far away, the foreman of a waste disposal crew calls a work break when one of his men becomes light-headed. Meanwhile, at a metalworking factory in a neighboring town, a medical emergency is declared when three cases of heat exhaustion are reported in a two-hour period.
What do these industrial casualties have in common? It was a hot midsummer afternoon; the humidity was unusually high; and the cause of the incident was determined to be a condition known as heat stress.