Scene Management: Approach, Isolation, Control Zones, and Command Practice Questions

25 multiple-choice questions on Scene management: approach, isolation, control zones, and command for paramedic and EMT students, from Chapter 50 (Hazardous Materials). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

25 practice questions

1. A tank truck has crashed on a bridge, and a liquid is pouring into the creek below. Along with staying upwind, your ambulance should approach from:

   1. A. Downstream of the spill
   2. B. Over the bridge
   3. C. The bank below the bridge
   4. D. Upstream of the spill
   Show answer

   Answer: D. Upstream of the spill

   Liquids carried by moving water travel downstream, so responders approach and stage upstream as well as upwind and uphill. Crossing the bridge or working on the bank below puts the crew in the product's path.

2. You are dispatched to a chlorine leak at a water treatment plant. The weather service reports the wind is blowing from the west. You should approach the plant from the:

   1. A. East
   2. B. North
   3. C. West
   4. D. South
   Show answer

   Answer: C. West

   Winds are named for the direction they come from, so a west wind carries the gas toward the east. Approaching from the west keeps the crew upwind; approaching from the east, the tempting answer for those who think of where the wind is going, drives straight into the plume.

3. You stop at what seems a safe distance from a leaking tank. A simple field check of your distance is to:

   1. A. Wait until you can no longer smell anything
   2. B. Check that no visible vapor is drifting your way
   3. C. Hold up your thumb; it should cover the scene
   4. D. Make sure you are at least 100 feet away
   Show answer

   Answer: C. Hold up your thumb; it should cover the scene

   With your arm extended, your thumb should cover the whole incident; if any of it shows around the thumb, back up. Waiting until an odor fades is unsafe because some chemicals deaden the sense of smell or are toxic below their odor threshold. Watching for visible vapor misses the many toxic gases that are colorless, and a fixed 100-foot distance is too close for many products, whose ERG isolation distances are larger.

4. From your staging point, you can see a placard on a leaking trailer but cannot read it. You should:

   1. A. Read it with binoculars from where you are
   2. B. Walk up just close enough to read the placard
   3. C. Drive past slowly to read it from the cab
   4. D. Ask the injured driver to read it to you
   Show answer

   Answer: A. Read it with binoculars from where you are

   Binoculars let you read placards and ID numbers without moving into the hazard area. Driving past the trailer is tempting because it seems quick, but it can take the crew through vapor and leave the ambulance contaminated.

5. At a hazmat incident, the hot zone is the area:

   1. A. Where decon is carried out on patients and responders
   2. B. Where command, staging, and treatment are set up
   3. C. Where patients are tagged and loaded for transport
   4. D. Around the release, where entry is restricted
   Show answer

   Answer: D. Around the release, where entry is restricted

   The hot (exclusion) zone surrounds the release, and only trained personnel in proper PPE may enter it. Decon takes place in the warm zone, and command and treatment are in the cold zone.

6. The warm zone at a hazmat incident is also called the contamination reduction zone because it:

   1. A. Has the highest vapor levels
   2. B. Contains the decon corridor
   3. C. Holds the command post
   4. D. Is free of contamination
   Show answer

   Answer: B. Contains the decon corridor

   The warm zone lies between the hot and cold zones and contains the decontamination corridor, where people and equipment are cleaned before leaving. The highest contamination is in the hot zone, and the command post is in the cold zone.

7. Which activity belongs in the cold zone at a hazmat incident?

   1. A. Washing walking patients in a shower
   2. B. Removing entry suits
   3. C. Rehab and monitoring of the entry team
   4. D. Rescuing people near the leaking valve
   Show answer

   Answer: C. Rehab and monitoring of the entry team

   The cold (support) zone is free of contamination and holds command, staging, rehab, medical monitoring, and treatment of decontaminated patients. Removing suits and showering patients are decon steps that belong in the warm zone.

8. A firefighter asks you to step into the warm zone in your uniform to start an IV on a worker who has not yet been decontaminated. You should:

   1. A. Enter quickly wearing two pairs of nitrile gloves
   2. B. Enter if you wear a surgical mask and gown
   3. C. Start the IV at the edge of the decon line
   4. D. Stay in the cold zone and treat him after decon
   Show answer

   Answer: D. Stay in the cold zone and treat him after decon

   Without proper PPE and training, EMS stays in the cold zone and receives patients after decon; life threats are handled by trained personnel in the warm zone. Double gloves or a mask do not protect against chemical vapor or splash.

9. The decon corridor should be set up:

   1. A. In the cold zone
   2. B. In the warm zone, upwind and uphill
   3. C. Inside the hot zone, close to the release point
   4. D. Downwind of the hot zone, to carry off vapors
   Show answer

   Answer: B. In the warm zone, upwind and uphill

   The corridor runs through the warm zone from the hot zone to the cold zone and should be upwind and uphill so runoff and vapors do not flow into it. Placing it downwind would expose the decon team to vapor from the release.

10. In the ERG green pages, the initial isolation zone is the area:

    1. A. All around the spill, where exposure may be deadly
    2. B. Downwind of the spill where people should take shelter or be evacuated
    3. C. Upwind of the spill where the command post and staging are set up
    4. D. Covered by the vapor cloud that is visible from a safe distance
    Show answer

    Answer: A. All around the spill, where exposure may be deadly

    The initial isolation zone is a circle around the release where people may be exposed to dangerous, life-threatening concentrations upwind and downwind. The downwind area where people should be protected is the protective action zone.

11. A tank truck is leaking a toxic-by-inhalation gas on a sunny afternoon with no fire. The ERG green table lists an initial isolation distance of 100 m (300 ft) and a daytime protective action distance of 0.6 km (0.4 mi). You should:

    1. A. Isolate 100 m downwind; protect 0.6 km upwind
    2. B. Isolate 0.6 km all around; protect 100 m downwind
    3. C. Isolate 100 m all around; protect 0.6 km downwind
    4. D. Protect 0.6 km all around; isolate 100 m downwind
    Show answer

    Answer: C. Isolate 100 m all around; protect 0.6 km downwind

    The ERG green table gives two separate distances. First, isolate the initial isolation distance in every direction, upwind included, because people close to the spill may meet life-threatening concentrations. Then protect people downwind for the protective action distance, by evacuation or shelter in place; that area is a square whose length and width equal the distance. Isolating 100 m downwind and protecting upwind puts both actions on the wrong side. Using 0.6 km as the isolation circle and 100 m as the downwind zone swaps the two numbers, leaving people 100 m to 0.6 km downwind unprotected. Protecting all around while isolating only downwind leaves people right beside the spill on the upwind side unisolated and spends resources where the plume is not going.

12. A short release of a toxic gas will pass over a nursing home within minutes. Residents are frail and many are bedbound. The best protective action is to:

    1. A. Shelter in place with windows closed and HVAC off
    2. B. Evacuate the residents now, before the cloud arrives
    3. C. Shelter in place with the ventilation running
    4. D. Move the residents outside to an upwind parking lot
    Show answer

    Answer: A. Shelter in place with windows closed and HVAC off

    Sheltering in place is often safer when a release is brief or evacuation would take people through the plume, especially those who are hard to move. Closing windows and shutting off ventilation keeps outside air from being drawn in. Moving frail and bedbound residents takes far longer than the few minutes before the cloud arrives and can leave them outdoors in the plume. Leaving the ventilation running pulls outside air, and the vapor, into the building. Moving residents outside also exposes them directly if the plume shifts.

13. A tank truck carrying a flammable liquid is on fire on a highway. The ERG advises isolating the area in all directions for about:

    1. A. 50 m (150 feet)
    2. B. 800 m (1/2 mile)
    3. C. 100 m (330 feet)
    4. D. 8 km (5 miles)
    Show answer

    Answer: B. 800 m (1/2 mile)

    Fire involving a tank, rail car, or tank truck can cause a boiling liquid expanding vapor explosion (BLEVE) that throws fragments a long way, so the ERG calls for isolating about 800 m (1/2 mile) in all directions. A distance such as 100 m is suitable for a spill without fire, not for a burning tank.

14. An hour into a chemical leak, the wind shifts, and vapor is now drifting toward the cold zone where your ambulances are parked. You should:

    1. A. Stay put and close the ambulance windows
    2. B. Move the units, but leave the zones as set
    3. C. Hand out escape hoods and stay
    4. D. Relocate the zones and units upwind
    Show answer

    Answer: D. Relocate the zones and units upwind

    Zones are set by the current wind and conditions and must move when the wind shifts, so command relocates the cold zone, staging, and units upwind of the new plume path. Closing the ambulance windows leaves crews and patients in the vapor, and vehicles still draw in outside air. Moving the units alone leaves the decon corridor and cold zone in the vapor's new path. Escape hoods are short-duration devices for getting out, not for staying and working in a contaminated area.

15. The size of the hot zone at a hazmat incident is based mainly on the:

    1. A. Product, amount, weather, and terrain
    2. B. Number of patients and ambulances on scene
    3. C. Distance to the hospital
    4. D. Size of the hazmat team that will respond
    Show answer

    Answer: A. Product, amount, weather, and terrain

    Zone boundaries depend on the product's hazards, how much is released, wind and temperature, and the lay of the land. Patient numbers and resources affect staffing, not how far the hazard extends.

16. Movement between the hot, warm, and cold zones at a hazmat scene is controlled by:

    1. A. Tracking crews by radio from the command post
    2. B. Access control points at entry and exit
    3. C. Letting each crew pick the shortest path
    4. D. Posting signs at the cold zone border
    Show answer

    Answer: B. Access control points at entry and exit

    Access control points at the zone edges make sure that everyone who enters is checked and tracked and that everyone who leaves passes through decon. Radio tracking from the command post helps accountability but cannot stop a contaminated person from walking out without decon. Letting each crew pick the shortest path lets contaminated people cross into the cold zone. Signs at the cold zone border mark the line but do not control who crosses it.

17. In the hazmat group, the person who supervises the team working in the hot zone is the:

    1. A. Decon team leader
    2. B. Safety officer
    3. C. Entry team leader
    4. D. Staging manager
    Show answer

    Answer: C. Entry team leader

    The entry leader directs the entry and backup teams in the hot zone and reports to the hazmat group supervisor. The decon leader runs the decon corridor, and the staging manager holds arriving units.

18. The decon team leader at a hazmat incident is responsible for:

    1. A. Choosing which patients go to which hospital first
    2. B. Directing technicians as they plug the leaking valve
    3. C. Taking vital signs of the entry team before they go in
    4. D. Setting up and running the decontamination corridor
    Show answer

    Answer: D. Setting up and running the decontamination corridor

    The decon leader oversees the decon line, its team, and the process for both responders and patients. Pre-entry vital signs are the medical monitoring role, and destination decisions are made by EMS transport.

19. In the incident command system, entry, decon, and site access control at a hazmat incident are usually grouped as the:

    1. A. Logistics section under the command staff
    2. B. Planning section's technical specialist unit
    3. C. Hazmat group under the operations section
    4. D. Medical unit within the logistics section
    Show answer

    Answer: C. Hazmat group under the operations section

    Hazmat functions are usually organized as a hazmat group or branch reporting to the operations section chief. The medical unit in logistics cares for responders, and technical specialists in planning may advise, but neither runs entry or decon.

20. As you approach a crash, you see a puddle of liquid spreading across the road from a leaking trailer. You should:

    1. A. Drive slowly through it if it looks like water
    2. B. Drive around it on the downwind shoulder
    3. C. Stop just downhill of the spill
    4. D. Stop well short and avoid the spill
    Show answer

    Answer: D. Stop well short and avoid the spill

    Driving through a spill, even slowly or when it looks like water, can carry product on the tires, contaminate the ambulance, and ignite flammable vapor from the hot exhaust or catalytic converter. The downwind shoulder puts the crew in the vapor. Stopping downhill puts the ambulance where the liquid will flow.

21. Three workers who walked out of a plant during a release are heading toward your ambulance in the cold zone, coughing and covered in a wet residue. You should:

    1. A. Load them into the ambulance to start oxygen
    2. B. Direct them to a holding area to await decon
    3. C. Rinse them with a bottle of saline and load them
    4. D. Tell them to drive themselves to the hospital
    Show answer

    Answer: B. Direct them to a holding area to await decon

    Contaminated people who leave on their own must be stopped and directed to decon before they enter the cold zone, ambulance, or hospital. Loading them or sending them away by private car spreads the contamination to crews and the emergency department.

22. After the hazmat team arrives, the hot zone boundary is usually adjusted based on:

    1. A. Air monitoring readings and product data
    2. B. The point where the odor seems to stop
    3. C. The edge of the visible vapor cloud
    4. D. The ERG green-table distance for the product
    Show answer

    Answer: A. Air monitoring readings and product data

    Air monitoring for oxygen level, flammable gases, and toxic vapors, along with product references, lets the team set boundaries where readings are safe. Odor is unreliable because some chemicals are toxic below the level people can smell. A visible cloud does not show where invisible vapor has spread, and the ERG table distances are starting points for the first minutes that the team then refines with monitoring.

23. When setting the initial perimeter at a chemical release, the safest approach is to:

    1. A. Start small, since growing it is easier
    2. B. Use 50 feet, the same for each product
    3. C. Start large; shrinking it is easier
    4. D. Mark the visible cloud
    Show answer

    Answer: C. Start large; shrinking it is easier

    It is far easier to bring people back in than to move people out of an area that turns out to be contaminated, so initial perimeters should err on the large side. Many vapors are invisible, so the visible cloud underestimates the hazard.

24. The only road into a chemical plant with a gas leak comes from the downwind side. The best plan is to:

    1. A. Use the road but keep the windows closed
    2. B. Drive in quickly with the siren and lights on
    3. C. Use the road and stage at the plant's gate
    4. D. Find another route and approach from upwind
    Show answer

    Answer: D. Find another route and approach from upwind

    Arriving from downwind puts the crew into the plume, and vehicles draw outside air into the cab even with the windows shut. Taking a longer route to approach from upwind is safer.

25. A chemical leak at a tank farm is expected to continue for many hours, and the vapor will reach a nearby neighborhood in about an hour. The best protective action for residents is usually to:

    1. A. Shelter in place until the leak is stopped
    2. B. Evacuate them before the vapor arrives
    3. C. Evacuate them once the vapor reaches the area
    4. D. Shelter them in a basement or low room
    Show answer

    Answer: B. Evacuate them before the vapor arrives

    Evacuation is preferred when there is time to move people before the plume arrives and the release will last long, because indoor air slowly fills with vapor during a long release. Sheltering in place suits short releases or when evacuation is unsafe. Waiting until the vapor reaches the neighborhood forces people to move through the plume. A basement or low room is a poor shelter because many toxic vapors are heavier than air and collect in low areas.