According to Bloomberg Environment (subscription required), EPA’s Clean Air Science Advisory Committee cannot reach agreement whether to recommend that the NAAQS for PM2.5 be lowered. 
Even after two years, I guess I had not realized the extent to which the scientists relied on by this administration are willing to ignore what used to be generally known as the “scientific consensus.”
As I reported last month, EPA’s Office of Air Quality and Standards released a draft reassessment of the adequacy of the PM2.5 NAAQS. The draft states that:
"The risk assessment estimates that the current primary PM2.5 standards could allow a substantial number of PM2.5-associated deaths in the U.S.
When taken together, we reach the preliminary conclusion that the available scientific evidence, air quality analyses, and the risk assessment, as summarized above, can reasonably be viewed as calling into question the adequacy of the public health protection afforded by the combination of the current annual and 24-hour primary PM2.5 standards."
Based on the analysis in the draft, it seemed obvious to me that EPA would have to lower the NAAQS to somewhere between 8.0 ug/m3 and 10.0 ug/m3. I assumed and predicted that EPA would propose to lower the standard as little as possible, to 10.0 ug/m3.
It turns out that four out of six members of EPA’s significant reconstituted Clean Air Science Advisory Committee think that the current standard should be retained. I doubt that the American Lung Association will agree.
I have previously speculated, in connection with matters ranging from BLM standards for methane emissions on federal lands to the EPA/DOT decision on CAFE standards, that, if this administration consistently flouts the scientific consensus on appropriate regulatory standards, then, at some point, courts will stop defea