Water as we are aware exists in the states of a solid (ice), liquid, and a gas (steam). The major factor that differentiates these three states is the motion of the molecules that comprise water. When heat (as in the form of friction caused by movement) is added, its molecules will move faster and freely interact. As water freezes, the movement of molecules slow down and begin to align in a crystal like structure resulting in ice. As water freezes, its density (or mass per unit volume) will also increase until it reaches a solid crystallized state. If water is constricted as in a hoseline or piping when this expansion of mass takes place, the pressure exerted can cause costly damage. For this reason, keep nozzles, deck guns, ladder pipes etc. partially open with water flowing until ready to shut down and pack up. Hoselines and ladderpipes should be drained and picked up immediately when they stop flowing water and are no longer needed.
Injuries & Rehab
Slips and falls are another prevalent hazard during cold weather operations. The soles of many firefighting boots worn will become harder in colder temperatures preventing them from "gripping" the ground. Removable cleats or spikes that slip over boot soles can be advantageous in this situation.
Water on the ground from cold weather operations will also create an increased potential for slips and falls. Sodium Chloride or road salt is commonly carried on fire apparatus due to its ability to impede ice formation. Road salt is often applied to the ice once it is already formed. Unfortunately, the salt must first be dissolved before it can work effectively. Salt works by breaking chemical bonds and preventing water molecules from aligning in the crystal state that we talked about. If salt is applied before water freezes, it will be readily dissolved and will effectively lower the freezing point of the water. Sand can also be thrown onto the ground to improve traction.
Rehabilitation resources and additional alarms should be requested as soon as possible. The rehab location should get firefighters out of the elements, be located away from vehicle exhaust and concentrate on providing hydration through warm fluids.
One of the most overlooked ways of protecting ourselves from cold stress is through proper hydration. This needs to take place prior to responding to an incident to make certain that our body's systems are working at their best. Vital functions of our body will shut down when not properly hydrated. During work cycles it is recommended that a firefighter drink at least a quart of water per hour.
Firefighters will only be able to battle the elements for short periods of time in extreme weather due to stress and shorter work cycles should be adhered to. Turnout gear does not allow for effective heat dissipation and sweating from performing fireground activity can lead to shivering and lowering of the body core temperature. Body core temperatures falling below accepted levels can cause severe injury to firefighters without them even realizing what is happening to them. Stress from the cold decreases cognitive reasoning as well as focus.
Frost bite is caused by parts of the body being exposed to extreme cold. It can result from a very short time of exposure if cold enough. Fluids contained within exposed body part freeze causing blood vessel damage and necrosis or death of tissue in the affected area. Several factors contribute to the severity of frostbite
- the temperature to which the exposed part is exposed
- the length of time which the body part is exposed
- the condition of clothing covering the exposed area (is it wet or dry?)
Most often the hands, feet, ears and face of a firefighter are most prone to frostbite. Frostbite will appear as changes in skin appearance as discoloration (white or gray) and will be accompanied by numbness and stiffness to the affected area. Often times a patient experiencing frostbite will not even realize it due to accompanying numbness. The best way to prevent frostbite is to protect skin from direct exposure to cold air. Firefighters should dress in layers of loose fitting clothes beneath their turnout gear. Materials of these clothes should allow evaporation of perspiration and not be restrictive as to compromise the body's circulation in helping to keep the body warm. Two pairs of socks and properly fitted footwear are also recommended.
Hypothermia results when the body core temperature falls below normal. Firefighters suffering from hypothermia will exhibit shivering, confusion, extreme fatigue and drowsiness.
The best way to prevent hypothermia is also to dress in layers beneath turnout gear and to keep moving when working on the fireground to maintain a good level of circulation. Firefighters should make certain to keep their heads covered with a hat or hood when working in cold weather. As much as 50 percent of the body's heat can be lost through the head and wearing a hat will help to minimize that loss.