Sometimes the perfect storm happens and the situation seems so innocent.  Here are the variables:

  • A new shop with a great ventilation system- the airflow moves from Bay 1 to Bay 5 in rapid succession
  • Bays 1-4 are mechanics who occasionally work on heavy equipment/ vehicles
  • Bay 5 is for welding- has local exhaust and ventilates directly outside


  • Welder usually does maintenance – small jobs
  • On one particular day he is laying down A LOT of wire- and preheats the metal
  • Same day- a mechanic needs to clean some parts and uses a cleaner found in most mechanic bays
  • Welder “smells” something unusual- get tightness in his chest and almost passes out

What occurred was the perfect combination for a deadly situation. Chlorinated solvents, when their vapors are heated, can form phosgene.

Here is a link to the CDC regarding phosgene. Abbreviated as CG by the military- since it was used in WW1 as a weapon.