[sammyg2]

Hope he wears good respiratory protection.

One thing about petroleum resid and petroleum coke:
It's the end of the trail, the bottom of the crude oil barrel.
As such it has lots of nasties entrained. Anything that can be found in the earth, only more concentrated.
Things like heavy metals and radioactive stuff.
Anything non-combustible that is in the resid will end up in the carbon black soot.

It's not uncommon for people who work with that stuff for a long time to end up with colon cancer.
I knew four former maintenance co-workers from one plant who died from colon cancer. The maintenance building was directly across a small road from the coke drums.
There were maybe 200 maintenance staff at that plant, and I worked there for 9 years.
4 out of 200.