This is disturbing, if true. The “if true” part is extremely important here.
One interesting point is that whichever way it goes, the EPA loses. If it turns out that particulate matter is as dangerous as the EPA has claimed, they’re knowingly subjecting experimenters to deadly poisons with absolutely no benefit (as their informed consent statement shows). If, on the other hand, they are not knowingly subjecting experimenters to deadly poisons, this would imply that their stance on particulate matter is wrong and that regulation should disappear in a puff of smoke.