The Body’s Response to Heat and Cold Your body works best when it has an internal “core” temperature of 37°C. 37°C might seem warm, but this is your internal temperature (not the air temperature). This temperature is necessary for your vital organs to function normally. During a regular day, your body temperature may vary by about 1°C depending on the time of day, your level of physical activity and how you are feeling (emotional reactions). The body’s metabolic processes produce the right amount of heat you need when you digest your food and when you perform physical activity. Maintaining Balance: When you work in extreme temperatures, your body has to adapt. To maintain constant inner body temperature, the body must continually keep or gain heat in cold environments and lose heat in hot environments. To stay warm in cold environments, the body • Shivers – moving muscles help increase heat production, and • Reduces blood flow to the skin and extremities (hands and feet) to reduce heat loss from the surface. To stay cool in hot environments, the body • Sweats – evaporating sweat cools the body, and • Increases blood flow to the skin – to speed up the loss of heat from the skin (radiate away the excess heat) if the outside air is cooler. By sweating, shivering, and changing the rate of blood flow, the body can adapt to a fairly wide range of temperatures. However, there are limits to what the body can adapt to and its ability to maintain its core temperature can fail. So dress in layers and prepare for the environments you will be working in.

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