Relief from heat stress now a priority

The human body has a narrow operating range for its internal temperature. The average temperature is regulated at around 36.1 to 38.3°C.

To create this temperature, the body converts or burns the chemical energy in food.

During exercise or physically demanding work, the body needs more energy to operate. When it burns more energy, the body temperature goes up.

To control the rise in body temperature, a complex thermoregulatory system takes action to lower body temperature to normal. If the air temperature is hot, the thermoregulatory system must work even harder to control body temperature. When the body's temperature rises several things happen. For example, the temperature of the blood also rises.

The brain detects this rise in temperature and sends more blood towards the skin. In this instance, the skin attempts to act like the radiator of a car cooling system. Heat is lost as perspiration radiates through the skin to the cooler air. The rise in temperature also triggers the sweat glands of the skin to sweat. More heat is lost as perspiration evaporates off the surface of the skin.

The body also gives off heat during the process of breathing. Relatively cooler air is drawn into the lungs, heat is exchanged and warm humid air is exhaled. In response to a higher body temperature, the brain also triggers a rise in the respiration rate to move more air, thus aiding the cooling process.

Now consider what happens when the body is placed in a hot humid environment. The air being inhaled is hot and therefore the heat transfer through the lungs slows down.

The hot air also limits the amount of body heat that can radiate out of the body through the skin. In fact, if the air temperature is higher than the body temperature, heat will be absorbed in the body.

High humidity also blocks the rapid evaporation of sweat, which further slows that rate of heat loss. If work or strenuous exercise is causing the body to create metabolic heat, then the classic conditions exist for heat stress-related illnesses.

Australia's harsh climate presents a difficult environment in which to control heat stress in workers. We have learnt to adapt the type of clothing we wear to suit the environment, we wear hats and we are more conscious of our fluid intake but still the risks exist.

Recent advances in polymer technology have seen the advent of products like MiraCool, which use an absorbant crystal that can be sewn into a range of garments including vests, hard hat inserts, sun hats and bandannas and that can be worn to help control the risks caused by heat stress-related illnesses.

While a cooling drink works from the inside out, MiraCool-infused garments work from the outside in to cool the blood and body. As warm blood vessels move closer to the skin in an attempt the transfer out heat, they make themselves accessible to the proactive cooling sensations delivered by the product.

When activated in cold water, the crystals plump up, absorbing up to 1000 times their weight in water. Once hydrated, they can be used for up to two full days without the need to rehydrate the product.

The water is then constantly released at about the same rate as human sweat. The crystals do not absorb heat, but retain the coolness of the water and work in combination with the body's natural evaporation process against the skin to keep you cool. Fresh cooling sensations continually occur without the user experiencing any warming effects as happens with standard cold compresses. The cooling sensations pass to pulse points and other blood vessels and are effectively carried throughout the body.

The constant evaporation process causes the product to be a few degrees cooler than the air temperature, therefore relatively cooling to the skin and body. The effect is similar to walking out of the shower - the water on human skin creates a lower than air temperature cooling effect on the skin.

When used together, the hat, vest and bandanna target the key areas where heat is generated including the head, torso, carotid and jugular arteries. The idea is that the gentle cooling effect helps to restore normal body temperature without the risk of chilling or causing shock reactions.