“Are we clean yet?” That’s how Jon Stewart got rolling on his interview with EPA head honcho Gina McCarthy last night.

She called climate change her top priority — “the biggest public health challenge that we face, as well as the biggest economic challenge we face” — and emphasized that the EPA’s proposed rules cracking down on carbon dioxide from power plants will be coming out in June.

“All these regulations put the mom ‘n’ pop oil companies out of business!” Stewart protested.

But McCarthy made the point that avoiding environmental apocalypse does not mean causing economic apocalypse. She boasted that the EPA over its 40 years has cut air pollution by 70 percent while the nation’s GDP has doubled.

Watch the whole segment, including Stewart joking about burning things in his backyard, bragging about his “Hummer within a Hummer within a Hummer,” and taking a jab at Texas: