The EPA’s CASAC PM subpanel voted last week to advise the EPA administrator to tighten the PM2.5 standards. The final advisory decision is now elevated to the main CASAC panel — most of the members of which are also on the subpanel. So the vote is basically predetermined. The only thing that can stop this is Young v. EPA lawsuit. Court argument scheduled for Dec. 22. Background on the EPA PM2.5 railroad.
Soot, unburned carbon, is not the same as PM 2.5 but rather a small component of PM 2.5. All PM 2.5 is not equal but rather made up of many different components and varies considerably through the USA.
The same ambient concentration will have different effects depending on the composition. Speciation should be required and controls based on the toxicity and concentration of the components.