The practice known as “rolling coal” occurs when a diesel truck is modified so that it can intentionally blast black smoke in abundance, and its origins can be traced back to truck pulling or power pulling competitions. Surprisingly, coal rolling is legal in most of the U.S., with only six states completely outlawing it: Maine, Utah, New Jersey, Maryland, Colorado, and Connecticut.

Federal laws banned drivers from modifying their vehicles in a way that could alter the level of emissions, but New Jersey was the first state to ban rolling coal in 2015. The targets for these laws are the diesel vehicle owners who deliberately rev their engines to blow smoke over pedestrians, cyclists, and passers-by, showing no concern for their health or care for the environment.

According to the Environmental Protection Agency, coal rolling is a major source of air pollution due to nitrogen oxide being released into the atmosphere. In addition, scientific research shows that inhaling toxic exhaust fumes can put individuals at risk of developing asthma, bronchitis, and other respiratory infections. Prolonged exposure to diesel exhaust can also exacerbate allergies.