To the Editor:

Re “U.S. to Challenge California’s Right to Set Pollution Rules” (Business Day, Sept. 6):

The Times explains that the Clean Air Act “ g ranted California a waiver to set stricter rules of its own because the state already had clear air legislation in place.” But the article does not mention the reason California had enacted legislation: From the 1940s through the ’60s, the Golden State had a staggering smog problem.

Far from “ f ailed policies” or “radical agenda,” as a Trump administration official termed them, the state’s laws pioneered a solution to toxic air pollution that was eroding the health of millions of Americans. A revocation of California’s waiver threatens a return to the type of lung-searing smog currently endured by Beijing’s residents — and dramatically on view during the 2008 Olympics.

Ellen Fisher

Newton, Mass.

To the Editor:

Re “U.S. Investigates Emissions Pledge” (front page, Sept. 7):

So, the Trump administration is now going after the four auto companies (Ford Motor Company, Volkswagen of America, Honda and BMW) that have dared to cooperate with California to lower exhaust fumes and make the planet cleaner. The arrogance of President Trump is astonishing.

California is taking steps to reduce global warming — which scientists agree is both real and existential — and Mr. Trump tries to punish the companies. The nerve!

Companies don’t often take positions that support the public good, and to punish the few that do is truly despicable and outrageous. If anyone had doubts about getting rid of Mr. Trump before now, this should be the last straw.