Anhydrous Ammonia Release at a Cold-Storage Warehouse
At 06:10 a 10 cm anhydrous ammonia line ruptures during maintenance at a cold-storage warehouse. A white vapour cloud is drifting across the loading dock, where about 12 workers are standing. Two maintenance workers are inside, 30 m from the door: one is crawling toward the exit and calling for help; the other is motionless beside a compressor. Wind is 3 m/s from the west, temperature −2 °C. The nearest hazmat team is 35 minutes away; the fire department is 12 minutes away. Your four-person rescue team has structural turnout gear, leather gloves, two 30-minute SCBA sets and a thermal imager, but no chemical-protective suits. The warehouse manager is shouting that you must go in immediately because the men will die, and one of your team members volunteers to enter with SCBA only.
1. Describe your scene size-up and hazard control in the first 10 minutes, including zones and public protection.
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Size-up first.
- Identify the product and its behaviour: anhydrous ammonia is corrosive, toxic and lighter than air at ambient temperature; a cold release can form a dense aerosol that hugs the ground. IDLH is about 300 ppm.
- Establish command, evacuate the loading dock and the downwind area, and approach from the west, upwind and on higher ground.
- Isolate at least 150 m for a large release and consult the ERG and the hazmat team for downwind protective action distances; deny entry to all non-essential people.
- Eliminate ignition sources, though ammonia is flammable only in a narrow range; the main risks are toxicity and corrosion.
- Account for the 12 dock workers and move them upwind; decontaminate anyone with vapour exposure.
- Request fire, EMS, hazmat and the plant engineer; establish a casualty collection point upwind. These actions address the hazard before any rescue attempt and define where rescue can safely occur.
2. Decide whether to enter, specify what PPE would be required, and explain how you handle the manager and the volunteering team member.
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No entry in turnout gear with SCBA alone. Structural turnout offers limited chemical resistance and no vapour protection for the eyes and skin; ammonia requires at least Level B (SCBA plus chemical-protective clothing) and preferably Level A for a high-concentration release. Your team does not have that, so the correct decision is defensive.
- A conscious, mobile casualty may self-evacuate; direct him with voice commands and use a fog stream for cover, but do not send an unprotected rescuer.
- The motionless worker is a recovery, not a rescue, until a properly equipped team arrives; entering would likely add a second casualty.
- Tell the manager clearly that an unprotected entry would create more victims, and that the hazmat team is the only safe option; document the refusal and the rationale.
- Keep the team back, brief the arriving fire/hazmat crew with product, location, number of victims and wind direction, and set up decontamination.
3. The conscious worker is brought out by the hazmat team. Describe decontamination and medical management, including the airway risk.
Read the worked answer
Decontamination and care.
- Remove all clothing and jewellery, double-bag them, and irrigate skin and eyes with copious water for at least 15–20 minutes. Do not neutralise ammonia with acid; the reaction generates heat.
- Protect yourself: gloves, apron, eye protection; avoid direct contact with contaminated clothing.
- Oxygen by mask, continuous monitoring, and early airway assessment - ammonia causes laryngeal oedema and burns, so look for hoarseness, stridor, drooling and soot.
- Have suction and airway equipment ready; if stridor develops, prepare for a difficult airway and rapid transport.
- Treat pain, keep him warm, and transport to a burn or toxicology-capable centre, pre-alerting about the exposure and the expected airway risk.
- Record exposure time and concentration if known; symptoms can progress over hours, so do not discharge him from the scene because he initially feels better.