Firefighters & Heat Stress

Firefighters & Heat Stress


The one statement that has probably been uttered by all Phoenicians a countless number of times when describing summer temperatures in Phoenix: “… but it’s a dry heat.”  The fact of the matter is that it does get hot here in Arizona–really hot. Summer temperatures regularly reach 115 degrees F or higher, resulting in a number of our dispatches being heat related.

Responding to these and other “routine” incidents becomes extremely taxing on our firefighters. Every year, we send firefighters to the hospital because they’ve been subjected to high heat stress while operating on an emergency scene. Despite our best intentions and being physically prepared, we simply can’t outperform Mother Nature. So our best chance of mitigating the ill effects of heat stress is by being smart, and staying hydrated and physically fit.

Heat Stress Indicators & Management
Temperature is not the sole indicator of heat stress. A day that’s 98 degrees F with 65% relative humidity will actually feel like 128 degrees F, according to the Heat Index Chart, which indicates the temperature that the body will feel when heat and humidity are combined. Note: These numbers are calculated in the shade and with a light wind present. Exposure to direct sunlight can increase the Heat Index by 15 degrees F. (This is why people refer to it as a “dry heat.”)

All of our responders will be stressed to some extent by high-temperature days, so every year our department reintroduces its Heat Stress Management procedures to minimize any effects. Heat Stress Management goes into effect when the temperature exceeds 105 degrees F or whenever the Heat Index reaches 105 degrees F. Dispatch will announce this over the deployment channel and will broadcast it to all stations, apparatus and portable radios. Each level of operations has a responsibility to implement these guidelines, starting with firefighters and moving up to incident commanders (ICs).

Firefighter & Officer Expectations
We expect our firefighters to come to work rested and physically fit. This includes implementing a diet that contributes to proper nutrition and hydration. In addition, we expect our members to stay home if they are sick and to notify their supervisor if they feel any ill effects while on-duty.

Our company officers are responsible for monitoring the physical activity of their crews. This includes physical training and emergency incidents. During Heat Stress Management, physical training is limited to 30 minutes and work/rest cycles are closely monitored. We also rely on our company officers to request additional resources more readily, to lessen the workload and stress of their crews.

Establishing Rehab
Operating within Heat Stress Management, incident commanders will establish a rehab sector on all working fires and assign companies to the rehab sector as needed. Our rehab sector consists of a rehab truck, a utility truck, a rescue and an ALS company. More units can be added to this as needed.

Our rehab truck is a large, air-conditioned RV that allows firefighters to rest and rehab within a cool environment before being reassigned. All apparatus are parked next to each other, and plenty of cold water, chairs, misters and shade are available. A battalion chief and their field incident technician supervise this sector and oversee the check-in, accountability, condition and rehabilitation of their crews.

Before returning to the incident or to quarters, our members must display certain vital signs. Any members showing abnormal vital signs will be treated and transported to the hospital for further evaluation.

Reducing the Effects: Acclimation & Hydration
If you talk to seasoned firefighters in our area, they’ll tell you that they start to acclimate their bodies well before the seasonal heat reaches its peak. Although there may be a variety of personalized ways to do this, the basic approach involves exposing your body to the heat a little at a time.

Here in the desert, the mercury starts to reach the 100 degree F mark in the month of May; therefore, acclimation should ideally start in April, especially if it’s going to involve donning full turnouts. Important: Remember that this is a process, not a test. Don’t make the mistake of seeing how much your body can take. Start out by wearing just your turnout jacket while you exercise outdoors. Then after a while, gradually add the rest of your PPE. Limit your workload and heat exposure at first, then gradually increase them. Pay attention to the weather forecast, prepare adequately, and don’t forget to wear a hat and sunscreen.

Another important way to reduce the effects of heat stress: hydration. During a recent visit to Arizona, a family member from the state of Washington commented on the fact that everywhere he went, everyone offered him a bottle of water. If you live here long enough, you’ll start to take a bottle of water with you everywhere you go.

Like acclimation, proper hydration starts before you really need it. Trying to rehydrate after a strenuous incident is much harder that staying hydrated during a strenuous incident. It’s not unusual in hot environments to lose up to two quarts of fluid an hour while performing manual labor. Add heat-retaining clothing and the body’s inability to adequately cool itself while covered in this type of clothing, and you have a recipe for disaster. Dehydration and electrolyte imbalance can become major issues in this scenario. Studies have found that profuse sweating can lead to a loss of 2% or more of one’s body weight, which can cause a drop in blood volume and makes the heart work harder.

Hydration Know-How
There are many recommendations regarding proper hydration. Some guidelines recommend drinking 1 mL of water for every calorie expended; however, we have no idea how many calories we burn while fighting a structure fire in the middle of summer. Other guidelines recommend observing the color of your urine; however, on the fireground, you may not urinate for some time.

I think the most reasonable and usable method is a combination of the above. The baseline water intake for an average person performing average activities in average environmental temperatures is about nine glasses of water per day. But most of the people I know don’t fit into this “average” category, so nine glasses is an absolute minimum requirement.

Recommendations from our department’s Health Center state that two quarts of water per hour should be consumed during periods of strenuous activity in hot weather. An electrolyte replacement drink should be added with every three quarts of water consumed. Less water intake is needed if the activity and heat index are not high. Monitoring your urine output and color when you can will give you some idea as to how this regimen is working. Regular output and light colored or clear urine is desired. Darker yellow or even brown urine is a sign that you need to drink more water.

As we know, there are many benefits to being physically fit, including your ability to acclimate, recover and return to work sooner. A more conditioned cardiovascular system recovers more quickly than one that is not as conditioned. It’s estimated that an unfit person takes up to 50% longer to acclimate to hot weather than a fit person.

This is due to a number of reasons:  First, a fit person usually has less body fat, which helps with cooling because heat can’t dissipate as well through fat.  Secondly, higher fitness levels result in improved circulation within the capillary beds. This increases the body’s cooling capability by enhancing flushing of the skin. In addition, a strong cardiac output can supply large amounts of blood to the muscles and from the muscles to the skin where heat can be dissipated.

But even the most prepared responders can fall prey to the heat and the physical stress that it wreaks on the body. By being prepared, you can increase your overall health and your time spent on the fireground, and decrease your chances of taking a trip to the hospital this summer.