The workplace is seldom an ideal environment and this can lead to workers becoming exposed to physical extremes of temperature. The human body functions best in a moderate climate, and variations that can lead to lowering or increasing of the body core temperature can lead to serious physiological injury or illness. Workers in hot environments; around furnaces, boilers, smelters and out in the sun – as well as in cold environments; in freezer plants, cold storage facilities – can be subjected to considerable thermal stress. ARECC recognizes and measures the physical factors contributing to heat stress and how the worker’s body respond to them so that control procedures are recommended and implemented to control these adverse risk factors.