[Cindya]

My nephew was injured in a parcel spill while working at his post office in Orlando, Florida. Later the package was mishandled and has disappeared. My nephew is now gravely ill and his doctors need to know what he was exposed to - any ideas or leads are welcome. His description:
Smell: overwhelming, horrible, strong, unlike any other smell. Very stinky. (His description)
Colors: the wetness was very dark, almost blackish - could have been any very dark color
Air: going into the area the air was "denser", he refers to it as like a "cloud" but the air was not foggy
He felt the true impact when he bent over the bag containing the broken package: the vapors were thick, dense and heavy for a couple of feet above the package
Symptoms: immediately the inside of his nose and throat burned in breathing it in. He immediately developed an intense headach behind his eyes in the brow area.
In moving the package some spilled on his forearms. In washing it off he said it was thick, syrupy, and sticky.
Any help and or ideas will be greatly appreciated. We have been working with a variety of resources to try and track down this parcel and have so far been unsuccessful. Daily he becomes sicker. Sorry that I can not give a better description. That I am even asking this question is a sign of how desperate we - his family are.

[Arkcon]

Surely, if something unknown has caused such a severe reaction, law enforcement authorities, for example the police (if not the FBI and Homeland Security,) have begun looking into tracking the parcel.  The observations you've provided aren't very useful for identification.  Saying odor as "stinky" and "unlike any other" are not useful -- we might be able to work with better terms, like "skunky" or "sulfurous" or "ether-like"