EMT · Scene Size-Up and Safety · 7 min read
Fire, Electrical, Structural, Vehicle and Environmental Hazards
- Identify atmospheric and explosion hazards at fire scenes, including the properties of toxic gases and the limits of standard protective gear.
- Describe scene safety protocols for electrical wires, ground gradients, and flammable gas leaks.
- Explain proper procedures for structural collapse zones, environmental threats, and vehicle stabilization during extrication.
Fire, Toxic Gases, and Explosion Hazards
Smoke generated by structural fires contains lethal combustion products that present immediate threats to human life. Carbon monoxide and hydrogen cyanide are two important toxic gases that may be present in smoke from structural fires. Carbon monoxide binds to hemoglobin with an affinity over two hundred times greater than oxygen, preventing normal oxygen delivery throughout the body. At the same time, hydrogen cyanide inhibits cellular respiration by preventing cells from using oxygen. Exposure to these gases rapidly starves body tissues of oxygen at the cellular level.
Responders must understand the physical boundaries of their equipment before approaching a fire scene. Standard emergency medical service turnout gear does not provide respiratory protection against toxic smoke or oxygen-deficient atmospheres. Because of this limitation, EMTs must never enter a burning structure or smoke-filled environment without specialized training and a self-contained breathing apparatus. Entering without proper breathing protection quickly incapacitates a rescuer, creating an additional patient and worsening scene management.
Positioning emergency apparatus correctly is critical when responding to fires and chemical hazards. Emergency vehicles should be parked uphill and upwind from fire, smoke, and chemical vapor hazards to avoid accumulating toxic fumes around the crew and patient compartment. Heat exposure can also cause catastrophic mechanical failures in closed containers; a boiling liquid expanding vapor explosion can occur when a pressurized container holding a liquefied gas is exposed to intense heat. Furthermore, scenes involving explosions demand constant vigilance, as secondary explosive devices are designed to injure first responders arriving after an initial blast.
Common mistakes
- Entering a smoke-filled structure wearing standard EMS turnout gear, incorrectly believing it provides respiratory protection against toxic gases like carbon monoxide and hydrogen cyanide.
- Assuming undeployed airbags are safe to work around immediately after a 12-volt battery is disconnected, forgetting that backup capacitors can store power for several minutes.
- Assuming an electric or hybrid vehicle is completely powered down simply because there is no motor noise, rather than checking for a READY indicator from a safe position.
- Walking with large steps away from a downed electrical line instead of shuffling feet together without lifting them to prevent electric shock from ground gradient.
Key points
- Carbon monoxide binds to hemoglobin with an affinity over two hundred times greater than oxygen, while hydrogen cyanide inhibits cellular respiration by preventing cells from using oxygen.
- Standard EMS turnout gear does not provide respiratory protection; EMTs must never enter burning or smoke-filled structures without specialized training and a self-contained breathing apparatus.
- Park emergency vehicles uphill and upwind from fire, smoke, and chemical vapors, and treat all downed power lines as energized until the utility company confirms they are disconnected.
- To avoid shock from electrical ground gradient, shuffle feet together without lifting them, and instruct occupants of electrified vehicles to remain inside unless life-threatening fire forces an exit.
- Natural gas generally rises, whereas propane can collect in low-lying areas; both are commonly odorized, but a leak may have no detectable odor, and EMTs should avoid operating potential ignition sources in the hazard area.
- Building collapse zones extend horizontally at least one and a half times the wall height, and unstable structures must only be entered by specialized technical search and rescue personnel.
- Vehicle extrication requires stabilization appropriate to the vehicle’s position, maintaining clearances of at least ten inches from driver airbags and twenty inches from passenger airbags, and avoiding orange high-voltage cables.
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Sample lesson: Scene Safety, Standard Precautions and PPE Selection25 practice questions on this exam
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