Anti-environmentalists have found a new medium for exhausting their anger: exhaust. Literally.

Some truck enthusiasts are intentionally producing copious amounts of diesel exhaust, spewing black smoke into the air as a form of political protest. It's called "rolling coal." Vocativ covered the subculture in an article last month, reporting "coal rollers" can spend thousands of dollars altering their rides to produce ever greater amounts of smoke.

Modifications include a variety of components that increase the amount of fuel entering the truck's engine. When there's so much fuel that it fails to combust properly, "it leaves the engine as soot," according to an article on DieselHub.com, a website dedicated to diesel truck owners.

That soot, which coal rollers call "Prius repellent" in online videos and forums and on decals on their trucks, can then be channeled up through "smoke stacks," where it exits onto bystanders (or a Prius following too closely) in a thick, pollutant-heavy black cloud.

“I run into a lot of people that really don’t like Obama at all,” an unnamed Wisconsin seller of smoke stack kits told Slate's David Weigel, explaining some of the rationale behind the movement. “If he’s into the environment, if he’s into this or that, we’re not. I hear a lot of that. To get a single stack on my truck—that’s my way of giving them the finger. You want clean air and a tiny carbon footprint? Well, screw you.”

In addition to the negative environmental impacts of increased emissions, the American Cancer Society has linked exposure to diesel exhaust to a variety of negative health effects, including lung cancer.

See more photos and video of coal rollers, below: