For Chlorine Safety, Follow the Jack Rabbit
DHS’ Jack Rabbit Project aims to understand the dangers faced by first responders and others in the event of a catastrophic chlorine gas release. Since 2015, researchers from the Utah Valley University have teamed with DHS researchers to conduct experiments in the Utah desert recreating a large release of chlorine gas. The results, detailed in Final Report: Jack Rabbit II Project’s Impacts on Emergency Responders: Catastrophic Releases of Liquefied Compressed Chlorine 2015 – 2016, have implications for the planning and execution of emergency response to chlorine releases.
Chlorine has an IDLH (Immediately Dangerous to Life and Health) level of 10 ppm (parts per million). In experiments conducted by the researches, concentrations reached over 100,000 ppm. Even at 200 meters away from the source, levels topped 70,000 ppm. Researchers also studied how wind affected the dispersal and path of the gas plume. The conclusion was simple: “Wind is King” (though terrain is important, too). The interaction of terrain and wind also revealed behavior that is not included in the ALOHA software model used to simulate and plan for toxic gas cloud emergencies, a key limitation for organizations to keep in mind.
They report includes some recommendations if caught in a chlorine plume:
1) It is almost always better to stay inside than go outside.
2) Close exterior openings and stop ventilation systems when feasible.
3) Retreating to an interior room, without windows and away from exterior walls, provides a magnitude of protection. A closet is ideal because all of the fabric hanging has a higher sorption rate than a bathroom with tile and glass surfaces.
4) Stay inside until the outdoor concentration is lower than the inside concentration.
More recommendations come from their study of the effect of chlorine gas clouds on the operation of emergency responder vehicles.
Vehicles continued to be operational even when exposed to ultra-high concentrations of chlorine. Escaping a chlorine plume lateral to the wind in a vehicle is the best course of action if the public or emergency responders find themselves in that position.