President Donald Trump’s eldest son on Wednesday retweeted a USA Today article on the new study and wrote: “Just when you thought you’ve seen it all... now we have RACIST AIR. This insanity has to stop.”

Twitter users tore into Donald Trump Jr. after he ridiculed a scientific report highlighting how minorities are disproportionately harmed by air pollution .

Just when you thought you’ve seen it all... now we have RACIST AIR. This insanity has to stop. https://t.co/fWPl4esIAu

“It’s been well established that poorer folks and minority communities tend to live in areas that are more polluted. This isn’t particularly new,” Samantha Gross, of the Brookings Institution think tank, said of the study.

Trump Jr.’s tweet “contradicts what we know” and is “based in ignorance,” Gross added to Newsweek.

Tweeters called Trump Jr. out for trying to reduce the important issue of environmental racism ― which has received vast media coverage in the past ― to a joke.