Samantha,

Before you design how to set it up, you may want to consider the training objectives of what needs accomplished and begin from there. The potential inhalation hazards are different from the evaporation rate from a liquid spill pool (typically longer) than an active gas leak. I'm going from memory, but you may want to consider and apply Fick's Law of Diffusion (was that his first or second law?) Anyway it's late after a very long week, but typically isn't inhalation the primary route of entry? Most gases are invisible, would carbon dioxide, theatrical smoke or anything else that keys the training on a visible response be the most appropriate?

May I propose an alternative? You may want to consider using methyl mercaptan (ACGIH TLV-TWA of 0.5 ppm, but odor threshold of 1 ppb) or a gaseous or aerosol form of capsaisin (no occupational exposure limit established, but highly irritating, e.g., pepper spray.)

Have I done anything similar? Yes, but not intentionally.

I would suggest focusing on the industrial hygiene monitoring, e.g., relying upon the proper instruments that have been bump tested rather than relying on visual indicators to apply the appropriate levels of controls.

Spill conditions change, e.g., release rate, wind speed, direction, etc. all impact what you are training for.

In this training you are trying to focus on gas recognition, migration, perimeter limits/controls? Assuming you mean natural gas, which typically has 1 ppm methyl mercaptan added as an odorant/identifier, I would recommend that you use one of the surrogates mentioned to teach the proper recognition and evaluation of the hazard to direct the controls required to respond, letting the response play out as dictated by weather, terrain, Fick's Law(s), etc.

FYI, while at a previous employer I performed a hazard assessment, specifying controls for a lengthy toxicology ingestion study of capsaisin. The assessment, engineering controls, training, etc. worked great until the primary formulations individual took a day of vacation. A (superiorly rated) substitute performed their respective duties on that day. The substitute was not "as thorough" or followed the same laboratory formulating skill procedure to practice good laboratory practices. The result was everyone in a 20-feet+ radius of the process received a non-toxic, but very irritating and immediately noticeable effect (and this was with good engineering controls).

In essence I would recommend selecting a gas or low concentration vapor that is easily produced, has a low or very low odor threshold with a high toxicity. I would steer away from teaching ERT members to respond to visible cues. Just the opposite, I think you should teach them to how to properly use and trust their instruments, focusing on being able to quantify the hazards from an invisible gas cloud - IF the instruments have been properly maintained, calibrated and bump tested.

I think in most cases of gas exposure you will be able to measure the concentration first, without relying upon site or odor. This is my opinion (albeit experienced) only.

Merry Christmas,

BruceV

From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**med.cornell.edu] On Behalf Of Samantha D
Sent: Friday, December 18, 2015 11:37 AM
To: DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Subject: [DCHAS-L] Gas Leak Training Input