Wildland Fire Safety header with photo of three firefighters silhouetted against flames LCES: Lookouts, Communications, Escape Routes and Safety Zones SAFENET Safety home page Contact Us Employment About Us News & Information Fire & Aviation Home 10 Standard Fire Orders and 18 Watchouts Fire Shelter Information Work Capacity Information USDA Forest Service United States Department of Agriculture
Heat Stress
Page 5 of

Before Work you should take extra fluids to prepare for the heat. Drink 1 to 2 cups of water, juice, or a sport drink before work. Avoid excess caffeine. It hastens fluid loss in the urine.

While working, take several fluid breaks every hour, drinking at least 1 quart of fluid. Drink as much as you can during the lunch break. Water is your greatest need during work in the heat. Studies show that workers drink more when lightly flavored beverages are available. Providing a portion of fluid replacement with a carbohydrate/electrolyte sport beverage will help you retain fluids and maintain energy and electrolyte levels.

After work, you need to continue drinking to replace fluid losses. Drawing of a firefighter drinking fluids.Thirst always underestimates fluid needs, so you should drink more than you think you need. Rehydration is enhanced when fluids contain sodium and potassium, or when foods with these electrolytes are consumed along with the fluid.

Sodium lost in sweat is easily replaced at meals with liberal use of the salt shaker. Unacclimatized workers lose more salt in the heat so they need to pay particular attention to salt replacement. Don't overdo salt intake; too much salt impairs temperature regulation. Excessive salt can cause stomach distress, fatigue, and other problems.



Make potassium-rich foods like bananas and citrus fruits a regular part of your diet, and drink lots of lemonade, orange juice, or tomato juice. In fire camp, limit the amount of caffeine drinks such as coffee and colas because caffeine increases fluid loss in the urine. Avoid alcoholic drinks. They also cause dehydration. Avoid sharing water bottles except in emergencies.

You can assess your hydration by observing the volume, color, and concentration of your urine--low volumes of dark, concentrated urine, or painful urination indicate a serious need for rehydration. Other signs of dehydration include a rapid heart rate, weakness, excessive fatigue, and dizziness. Rapid loss of several pounds of body weight is a certain sign of dehydration. Rehydrate before returning to work. Continuing to work in a dehydrated state can lead to serious consequences, including heat stroke, muscle breakdown, and kidney failure.


Personal protective clothing strikes a balance between protection and worker comfort. Australian researchers have concluded that:

The task for firefighter's clothing is not to keep heat out but to let it out!

About 70% of the heat load comes from within, from metabolic heat generated during hard work. Only 30% comes from the environment and the fire. Wear loose-fitting garments to enhance air movement. Wear cotton T-shirts and underwear to help sweat evaporate. Avoid extra layers of clothing that insulate, restrict air movement, and contribute to heat stress.

1 2 3 4 5 6