On May 4, 2017, the American Chemistry Council (ACC) released updated industrial hygiene guidelines for phosgene.  The guidelines specify the work practices and protective equipment necessary in the area of phosgene gas. These practices are based on the properties of the substance as detailed in the SDS, such as its toxicity, volatility and density. Since phosgene is a gas at standard conditions, it is typically stored cryogenically but in the event of a release it becomes a toxic gas that is quite dense so it does not readily disperse.  The Occupational Safety and Health Administration allows a weighted average level of .1 ppm of phosgene in the atmosphere of a workplace but the ACC states that due to the toxicity of the gas no background level is considered to be safe.  The gas has an odor but it is not reliably detected by smell at the .1 ppm level.  Colorimetric test badges are typically used, along with other atmospheric testing methods.  It is important that the testing methods sample the air at breathing level as well as near equipment and possible sources of the gas.  Personal protective equipment includes splash preventing eye protection, chemical resistant clothing, and access to full face self contained breathing apparatus both for workers and for emergency personnel.

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