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Category: EMS Operations

Topic: Scene Size Up

Level: EMR

Next Unit: Multiple Patient Situations

20 minute read

Above all other concepts presented during EMS training, the most significant is sizing-up the scene; that is, determining if there are hazards present that may affect responders, others associated with the incident, or the community at large.

Know that scene size-up begins prior to any calls for the day and should begin upon reporting to any assigned shift.


Environmental Conditions

Are there extremes in weather that could potentially impact responders or patients during the shift? 

Responders should evaluate the conditions present for that specific day. In particular:

  1. What are the environmental conditions for that day? Is the temperature > 100º degrees or < 32º?

    How might this affect responders when responding to calls in their service area?
  2. Is it raining, snowing? Are there storms or other acts of nature that could impact the ability to respond or manage patients?

    How might responders take these situations into consideration when planning for calls for that particular day?

After assessing conditions for a particular shift, responders should prepare themselves mentally and physically for any calls that may arise:

  • Check all personal protective equipment to ensure that it is in working order and present.

Is all life safety equipment available and working?

  • Additionally, review what additional resources are available and how they may be contacted if the need arises.
  • Upon receiving any call, if additional resources may be needed, never hesitate to call for them early.

They can always be canceled if it is determined they are not needed.

  • Upon receiving any calls for service, responders must attempt to determine if any extraordinary hazards exist.
    • Examine the nature of the call. Is there specific information in the report that may alert you to unsafe conditions? Are there reports of fire, explosions, strange odors, unusual smoke or clouds? Is the call in a location that has been unsafe before?
    • What is the location of the call? Is it in a rural secluded area, on a busy highway, at a school, or nursing home?
    • Attempt to evaluate all of these issues while responding to an incident.
  • Additionally, try to gather further information from dispatchers who may be talking to patients or others while you are responding. Other public safety employees who may be arriving at the situation or may have prior knowledge of facilities, locations, or people related to the call.

Hazardous Substances

Particular attention should be devoted to the presence or likelihood of hazardous substances at ALL incidents.

The acronym CBRNE can be used as a checklist prior to arrival for these potential hazards:

  • C = Chemical
  • B = Biological
  • R = Radiological
  • N = Nuclear
  • E = Explosive.

Are there any reports or is there a potential for any of these?

If so, how might one deal with these threats?

Most front-line EMS providers are not equipped to deal with CBRNE situations. Responders must be quick to recognize and identify their existence. Additional resources will need to be requested quickly if there is any potential of CBRNE substances present.

► REMEMBER, if you can hold your thumb up at arm's length and see any portion of the scene around your thumb, YOU ARE TO CLOSE! 



Additionally, responders must be aware of potential violence from patients, those associated with the patient, or bystanders.

Never assume that a call is routine:

► Many EMTs have been injured or killed by not recognizing that they were in a potentially volatile situation until it was too late.

Never hesitate to call for additional resources or police assistance. Staying ahead of the situation and being prepared may be the difference between life or death. Your safety is paramount. No one wins a prize for snatching a patient out of a bad situation and then becoming a victim of that bad situation. If law enforcement is not on scene or available, either have the patient come to you or wait until the scene is safe to render care. As difficult as this can be, placing yourself in a compromising situation puts you and your patient at risk. If you and your partner get hurt or worse, that does your patient no good. Always maintain situational awareness and don't get tunnel vision by putting your patient's condition above your own safety. 

Moreover, it is important to determine if there is an active crime scene. Are the police present?

When responding to a call that is a potential crime scene, remember that everything moved or touched may be evidence in that crime.

  • Keep a mental note of things touched, moved, or actions taken during that incident.
  • Upon completing that call, make detailed reports about all actions taken during the call.

In the event of a criminal trial, it will be much easier to remember any actions taken to move potential evidence. Explain the how, what, when, where, and why in every report, regardless of scene situation.



There are many potential hazards associated with rescue situations. Responders will be presented with rescue situations ranging from motor vehicle collisions, farm or machinery incidents, or special rescue incidents, i.e., swift water rescues, fire, or other special hazards.

Responders must identify training limitations when it comes to special rescue situations.

If responders are not trained or equipped to handle these technically specific situations, recognize and identify early and request additional resources to help alleviate the situation.

MVAs: One of the most common types of incidents responders will experience include motor vehicle collisions. These incidents present a number of hazards excluding the incident itself.

STRUCK-BYs (being hit by another passing vehicle while managing an incident) is one of the leading causes of deaths by first responders in the United States.

Ensure that upon arrival to any of these incidents, responders place a barrier between the incident and passing traffic. There are numerous options but one of the easiest is placing apparatus between responder work areas and traffic. Identify a location to place apparatus upon arriving at the scene that will provide protection. Additionally, if more resources need to be requested, identify that early and request them immediately. If additional resources are not needed, they can be canceled at any time.

Multiple windshield impacts imply multiple victims. 

VEHICLE EXTRICATION: Vehicle extrication is a potentially dangerous situation. There are numerous hazards associated with vehicle collisions that responders must be aware of, just a few being:

  • Broken glass,
  • rough, sharp metal edges,
  • fuel,
  • leaking fluids,
  • gases or vapors.

Silence is deadly: Be mindful of electric vehicles. With the advent of electrically powered vehicles, it is impossible to know by sound alone if the vehicle is capable of moving.

While any vehicle has the potential to shift or move, electrical vehicles may appear to be inoperable or not running but can potentially crush or injure if the accelerator pedal is pressed. Additionally, there are electrical hazards from these vehicles not seen in conventional gasoline vehicles.



There are many hazards seen and unseen that may be present.

Upon arrival,

  1. make a quick assessment of the situation.
  2. Recognize and identify if the scene appears to be safe.

    If the scene is safe,
  3. make patient contact and be aware of potential problems that may present themselves.

    If the scene is not safe, is it possible to quickly make the scene safe? i.e., separate yourself and patients from potential violent actors.

    Once the scene becomes safe, proceed with patient contact.

    If the scene cannot be rendered safe,
  4. immediately request additional resources, remain a safe distance from the location, and wait for the scene to be secured.