Chlorine Cloud and a Downed Driver

First five minutes, in this order:

1. Position upwind and uphill, off the low ground. Wind is from the west-southwest; stage apparatus west of the intersection and do not park in the vapor path. Traffic on Commerce is still moving behind you - that is an immediate life-safety problem, get PD to stop it upwind of the cloud, not through it.
2. Establish command and call for the right resources: hazmat response, additional alarms, EMS task force, PD traffic and evacuation, and the state environmental agency and water authority (this is going into storm drains).
3. Do not approach in turnout gear. Mixing hypochlorite and acid generates chlorine. Structural PPE is not chemical-protective clothing and will absorb and hold the product.
4. Establish an initial isolation perimeter consistent with the ERG for the identified products, and expand it - a chlorine-generating reaction with a visible cloud warrants a large initial isolation, on the order of 150 meters in all directions, adjusted for terrain and wind.

On the driver:

I will attempt a rescue, but on my terms, and only once. The victim is 15 meters out, unresponsive, inside the visible edge of the cloud, with a 20-minute hazmat ETA. A 20-minute wait is a body recovery.

The attempt requires: two firefighters in full PPE with SCBA, approaching from upwind and the flank so the cloud is pushed away rather than entered; a second two-person team as backup with a hard timer; a charged line at the entry point to protect the egress; a maximum exposure time of about 60 seconds at the victim; and continuous radio with a pre-agreed abort signal. A fog stream from a distance can push vapor off the victim before the grab.

What I will not do: send anyone in structural gear without SCBA, send a single firefighter, or attempt a second entry if the first fails. The victim is unresponsive and the atmosphere is IDLH; the calculation is one possible save against two certain casualties. If the cloud is too dense to see the victim, the answer is no.

And plan the decon before you move him: do not put a contaminated patient in the medic unit. Gross decon at the edge of the warm zone, cut off clothing, bag it, and tell ALS the patient is contaminated before they touch him.

Zones:

• Hot zone: the truck, the spill, the visible cloud, and the downwind plume path. Entry only by the rescue team, logged by name and time.
• Warm zone: upwind, sized for decon and the treatment area, with a single controlled entry point and a single exit point. Contaminated victims and contaminated clothing cross the boundary only through decon.
• Cold zone: command post, staging, media, and the medic unit - upwind and uphill.

Command structure: I keep command and appoint a safety officer immediately, because I am about to be too busy to watch the rescue. Groups: Rescue (the entry team), Decon, Medical, and later a Hazmat Group when the technicians arrive. Unified command with PD for traffic and evacuation. Staging officer to keep arriving units from parking in the plume.

To dispatch: "Route 9 and Commerce, confirmed hazardous-materials release, chlorine gas evolving from mixed pool chemicals, one victim down in the vapor, cloud moving east-northeast toward the Commerce strip mall. Request hazmat team, three additional ALS units, PD for evacuation, and notify state environmental and the water authority. Command is Route 9 Command on channel 3."

To the incoming medic unit, before they arrive: "Do not approach from the east. Stage west of the intersection at Second Street, upwind. You will receive one patient, male, adult, unresponsive, contaminated with chlorine and pool chemicals. He will come to you through gross decon at the warm-zone line. Bring airway and oxygen, but treat him as contaminated until we hand him off." Telling them in advance is what keeps a paramedic from walking into the cloud to help.

Shelter in place immediately, and plan the evacuation as a second decision rather than the first.

The timing math drives it. The mall is 200 meters downwind with an 8 mph wind. That is roughly 3.6 meters per second, so the cloud front reaches the mall in under a minute. There is no time to move people out through the path of the cloud, and an evacuation order that puts people into the plume is worse than no order.

Shelter in place means: get the message out now - reverse-911, PA from a vehicle upwind, and PD knocking on doors from the upwind side - close windows and doors, shut down HVAC, move to the interior and upper floors (chlorine is heavier than air and will pool low), and stay until given an all-clear.

When I would switch to evacuation:

• If the release is prolonged and the building cannot be sealed - a strip mall with storefront doors and rooftop units is not a tight structure.
• If the cloud is projected to persist for more than roughly 20 to 30 minutes, or the hazmat team cannot control the source.
• If the fire department can provide a safe route - upwind, away from the plume - which becomes possible once the cloud has passed or once fog streams knock it down.

Two things not to forget:

• Notify downwind beyond the mall. Eight mph carries this well past 200 meters, and the people nobody called are the ones who get hurt.
• Runoff. These products are going into storm drains and will reach a waterway. Containment later is cheaper than a fish kill, and the state agency needs to know now, not at shift change.

The trap in this scenario is treating the mall as the emergency. The mall is the consequence. The source, the plume, and the drains are the emergency, and the mall decision flows from how fast you control those.