While VW made international headlines in 2015 for intentionally misleading customers and cheating emissions standards and through the use of “defeat device” software, a subculture of American motorists, those who “roll coal,” are out to leave an even blacker mark on diesel. To “roll coal” is to produce billowing clouds of black exhaust from a diesel engine, particularly that of a heavy duty pickup truck through an after-market modification process. The standard set-up features a switch allowing the driver to selectively unleash the noxious plumes over such common targets as drivers of electric or hybrid vehicles, cyclists, and pedestrians.
Enthusiasts can install the kits themselves, or seek help from a professional. The kits override the normal fuel injection and emissions controls to flood the engine with excess diesel. Though diesel engines are typically more fuel-efficient than their gasoline counterparts, overwhelmed by extra fuel, the engine doesn’t fully burn the surplus, which exits as a thick sooty smokescreen and is capable of temporarily blocking out all visibility behind the offending truck. The density of the smoke is due to its high particulate matter composition, including perennial public menace, black carbon.
A known climate aggravator, black carbon absorbs sunlight then radiates the captured heat. The United States is already the world’s highest per-capita emitter of black carbon, of which over half is discharged from diesel engines—that’s normal ones. If rolling coal represents a growing trend and movement, its characteristically anti-environmental dogma is poised to deliver more than rhetorical effect.
In addition to its repercussions in the climate arena, diesel exhaust is a well-documented and severe threat to public health. The Clean Air Task Force reports that pollutants from diesel emissions in the United States alone lead to 21,000 annual premature deaths and represent a cancer risk sevenfold greater than the “combined risk of all 181 other air toxics tracked by the EPA.” Indeed, even brief exposure to diesel smoke can heighten the risk of heart disease, lung disease and cancer. In the case of rolling coal,
these statistics likely understate the danger, as the defeat device-equipped engines emit a much more toxic potpourri of exhaust, and are paired with the malicious practice of targeting cyclists and pedestrians, who are already breathing deeply.
One target, a Nissan Leaf-driving New Jersey state assemblyman, Tim Eustace, had a “terrifying” encounter on the New Jersey Turnpike, in which he “couldn’t see anything” after a pickup smoke-screened him. With the passage last May of a bill he sponsored, New Jersey has become the first state to outlaw rolling coal. That it not mince words, the text of the statute calls the practice out in all its colloquial glory, before prohibiting and establishing penalties for both the modification and actual intentional emissions of “significant quantities of soot, smoke, or other particulate[s].” Other states, including Colorado and Illinois, have tried but so far failed to pass similar legislation at the state level.
However, by mid-2014, the EPA announced rolling coal was conclusively illegal under the Clean Air Act. The Agency updated its website to clarify that to “manufacture, sell, or install a part for a motor vehicle that bypasses, defeats, or renders inoperative any emission control device” is a violation of the Clean Air Act (VW appears to have missed that memo).
There are signs that the coal rolling has already peaked following the knee-jerk upsurge in popularity following the EPA’s 2014 prohibition of the practice. Even before that announcement, a Utah-based company, Edge Products, settled with the EPA, agreeing in 2013 to pay a $500,000 fine after producing and selling “DPF delete kits”—electronic modules to allow pickup truck drivers to remove programming for the diesel particulate filter (DPFs) required in those trucks by law. The filter, as the name suggests, removes soot and other particulate matter from diesel exhaust, a feature as beneficial to humans with lungs as it is abhorred by would-be coal rollers.
But other enthusiasts have accepted, if not embraced, a transition away from conspicuous emission. Some diesel enthusiasts have criticized coal rolling, on the basis that it gives the performance truck community a bad reputation. Pointing to the “Rollin coal epidemic,” the popular truck website, Diesel Hub, notes that “continued abuse” of emissions defeating products is likely to cause retaliatory regulations for the performance truck industry. It may be just a matter of time until this trend goes up in smoke.