Since this keeps popping up on the front page and nobody seems to understand, here is the list of criteria air pollutants: https://www.epa.gov/criteria-air-poll

Since this keeps popping up on the front page and nobody seems to understand, here is the list of criteria air pollutants: https://www.epa.gov/criteria-air-pollutants/naaqs-table https://www.epa.gov/criteria-air-pollutants/naaqs-table As noted in the above link, Congress from time to time amends the Act to update the list, which was last done in 1990. That's all it takes: an amendment to the Act, passed by Congress. They can and have done this before, and yes, even with "climate deniers" signing off on it. The sole reason it hasn't been amended since then is because of the increased practice of doing omnibus bills and each group adding unreasonable expenditures and pet projects to otherwise uncontroversial legislation. How that gets stopped I have no idea, since the only legislators I am aware of who oppose that sort of thing get lambasted by hyper partisan media and the voters who gobble up that propaganda.