The body's need for water is obvious because 60% of the adult human body is made up of water. The brain itself is 75% water, our blood is 92% water, our bones are 22% water, and our muscles are 75% water. These body systems are the most used by firefighters when they are in the performance of their duties. Even slight dehydration can result in the compromise of some or all of these. A firefighter with compromised mental and/or physical capabilities presents an obvious threat to himself and the safety of the crew.

The firefighter, like the athlete, will perform acts of physical exertion in fire combat. Unlike the athlete, the firefighter is dressed to be protected from the environment and not for just optimum performance. The added stress of the danger that is inherent to firefighting and other mentally taxing factors makes the need for all of the firefighter's faculties to be as good they can be.

Dehydration will be the result of the body trying to regulate it's temperature naturally if there are not available fluids to replace what is lost through these processes. The body has two natural ways that it regulates it's temperature in situations of elevated heat. The first is the redirection of blood to the skin from the internal organs. This is so the heat can convect off and cool the body. The second is to sweat and cool the body through the evaporation of the sweat from the skin. Structure firefighters wear Personal Protective Equipment that involves a thermal layer and a vapor layer. If these layers allowed heat and moisture to escape while keeping the heat and water out it would be perfect. Unfortunately these layers don't distinguish between which way the heat and moisture is not allowed to pass. This means that the two natural ways to regulate the temperature of the body are inhibited and the body tries harder to make them work. This is how the extreme loss of water occurs and dehydration will result. The dehydration will disturb cardiac function, cause muscle cramps, slowed metabolism and cause other dysfunctions. The worst case scenario can be heat stroke or extreme electrolyte derangement that can lead to death.

The only way we can combat these problems is to understand the need to compensate for those factors that we have against us. Sweating will cause a lot of sodium loss with the water loss. The isotonic sports drinks are an efficient and effective way to replace both electrolytes and fluid. Too many of the isotonic can cause an over load of sodium causing the body to need more water to be able to slough it off through urination. So a combination of isotonic drinks with water will help to re-hydrate the personnel as well as help keep their sodium levels in check. There are some bottled waters on the market that have added fruit flavoring for taste. These can be used some carbohydrates burned up in the metabolism of the firefighter while working. But drinks that have over 10% carbohydrates have a tendency to slow the uptake of water and electrolytes. Most of these bottled waters are 6%-10% carbohydrates and will not interfere in this way. The key is to use the isotonic drinks and bottled water together to make the proper compensations for what is lost.

In light athletic activity the body can loose 8-16 oz. of water per hour. In active conditions this can increase to 32oz. to double that per hour. It is recommended that 8 oz. of water be consumed every 15 minutes during the times of normal exercise. The extreme conditions of firefighting demand more than this. The firefighter loses 16oz.of water for every pound of body-weight lost. This means a potential loss can be up to 4 pounds and maybe higher. One isotonic (16oz. Size) with three bottled waters of the same size each is about the exact amount needed. Caffeinated drinks and soft drinks have been used on the fire-ground before but the high sugar and caffeine only cause more dehydration. If a person likes to consume caffeine to increase their alertness, it's diuretic effects will need to be compensated for with an even higher intake of replacement fluids.

The firefighters need to consider these principles prior to the alarm for a service call. They need to keep well hydrated all day long by consuming 64 oz.+ a day to stay ready. When they exercise on duty, they need to increase their intake then as well to avoid being caught dehydrated at the scene of a fire that they were called to while working out. Practicing these principles of hydration can keep us all safer and healthier on the fire-ground and help to ensure a safe return home.

Firefighter Rodger Broome'

June 2, 1998