Firefighters Must Remain Hydrated to Successfully Battle Wildfires

By Lauri Byerley, Ph.D., RDN, LDN, FAND
Faculty Member, Sports and Health Sciences, American Military University

Over 7,000 fires burned more than 200,000 acres in California in 2019. Remember the Camp Fire in 2018? Now, Australia is experiencing its worst fire season on record.

These raging bushfires are a real-life reminder to firefighters that they must stay hydrated if they are to be effective in the field. It can mean the difference between life and death. Even mild dehydration can impair simple cognitive function.

The personal protective equipment (PPE) firefighters wear is heavy and hot, and it hinders the body’s natural evaporating mechanisms to cool down. Sweat is more than just water. Perspiration contains essential electrolytes, including sodium, potassium, calcium and magnesium, that the body loses in unequal amounts. These electrolytes must be replaced. Generally, five parts of sodium are lost for every one part of potassium, so every one-part potassium loss should be replaced by five parts of sodium.

Determining how much water, sodium, potassium, calcium and magnesium is lost is tricky. Although researchers have studied the hydration needs of wildfire firefighters, few studies have been conducted while firefighters are actually battling a blaze.

The Amount of Fluid Firefighters Need Depends on the Ambient Temperature and Other Factors

The amount of fluids that firefighters need depends on the ambient temperature, the length of their shift, the tasks performed, and individual differences such as body mass, sweat rate, and other personal factors. Because of the enormous variations, only general guidelines can be drawn.

Here are some helpful tips from me and the USDA’s Forest Service:

1. Follow your group’s leaders and what they recommend. They have the most experience with your location and conditions.
2. Be sure to stay hydrated every day. Wildland firefighters need to drink at least one quart of fluid per hour during hard work. If you are not adequately hydrated on one day, you can have a “hangover” effect the next day and not be at your optimal working performance.
3. Check the color of your urine. If it is a pale yellow or wheat-colored, you are drinking enough water. If it is dark or bright yellow, you need to drink more fluids. If it is a very pale or no color, then you may be drinking too much fluid.
4. When you sweat excessively, you need to replace the water and electrolytes you lost. There are several rehydration options, including many different carbohydrate-electrolyte beverages, food and electrolyte tablets. You need to be mindful of the electrolyte content of each. For example, the sodium and potassium ratio in some sports beverages is low in potassium and high in sodium, so you may need to eat food rich in potassium, like a banana, along with the sports beverage.
5. Depending on the situation and how much fluid you lose, it can take up to 24 hours to replace all the lost fluid and electrolytes.
6. Be sure to always drink while you are fighting a wildfire. Your group may have specific recommendations. Follow them.
7. Don’t over-hydrate (i.e., drink too much fluid and/or water) as that can lead to hyponatremia, which can be as dangerous as under-hydrating.
8. Thirst is not a good indicator of dehydration. If you are thirsty, be sure to drink, but remember, you can be dehydrated and not be thirsty.
9. It is possible to drink enough fluids but not replenish the lost electrolytes. Be sure to focus on hydration and electrolytes.

Remember, too, that the loss of too much body water and electrolytes can lead to heat exhaustion, heat cramps and heatstroke. Even worse, the loss of electrolytes can cause seizures, low blood volume, kidney failure, coma and even death. It’s easy to say that that won’t happen to me, so be smart and stay hydrated.

About the Author

Dr. Lauri O. Byerley, Ph.D., RDN, LDN is a nutrition scientist, nutrition educator and Registered Dietitian. Her research expertise is diet and cancer, and sports nutrition. She has written more than 30 peer-reviewed, original research articles in these areas. She has several decades of experience teaching a variety of nutrition courses at the college level.