Thanks for your comments. You are right, of course.
I had thought that the Hazardous Air Pollutant regulations were aimed at all
hazards of volatile materials. I learned the facts of life, as you describe
them, in my search throughout the EPA.
I still think that the EPA is missing something, since no one appears to be
considering HAPs outside of enforcing regulations on the 189 materials on
the original and outdated HAP list.