I guess you're not aware that the latest EPA rule proposals are taking aim at the very notion that PM2.5 is harmful (albeit indirectly)?
The legal authority to regulate PM2.5 is based on Harvard studies (that have been replicated) and private medical data from the 70s and 80s. The new EPA rule would forbid it from using non-public data (such as these medical records). The new rule would forbid using non-public datasets (such as medical records), which would make it practically impossible to issue regulations based on human health.
And it's a "proposed" rule, and that distinction matters.
Everyone sane agrees that the US is moving backwards on this issue right now. And likewise everyone can see that the numbers in the headline represent a huge step forward for China.
Nonetheless when comparing actual air quality[1] as measured by things like PM2.5, the US is remarkably clean and well-regulated even by standards of western democracies while China is starting from a state of pollution that the US never remotely approached.
Bucketing the world into Good Guys and Bad Guys works poorly if you want to effect real change.
[1] Per capita carbon output doesn't look nearly so good for the US, of course.
The legal authority to regulate PM2.5 is based on Harvard studies (that have been replicated) and private medical data from the 70s and 80s. The new EPA rule would forbid it from using non-public data (such as these medical records). The new rule would forbid using non-public datasets (such as medical records), which would make it practically impossible to issue regulations based on human health.