Engine maker West Virginia-based Cummins Inc. is facing the largest penalty ever imposed under the Clean Air Act after a series of accusations of emissions test cheating. The U.S. Environmental Protection Agency (EPA) has accused Cummins of outfitting half a million diesel engines with “defeat devices” that allowed the engines to pass emissions tests in the lab but produce illegal levels of nitrogen oxide pollution on the road. The EPA has ordered Cummins to pay civil penalties of $1.5 billion. The EPA alleges that from 1998 to 2015, Cummins developed and installed “auxiliary emission control devices” in engines used in heavy-duty commercial and off-road vehicles. It’s alleged these devices allowed the engines to pass emissions tests in the lab but produce illegal levels of nitrogen oxide when driving. In total, the EPA claims that Cummins concealed the existence of these devices in 500,000 engines and trucks built between 1998 and 2018. If found guilty, Cummins will be the first engine manufacturer to be handed the biggest Clean Air Act violation penalty in history. The company also faces additional lawsuits in 12 states for Clean Air Act violations. Cummins has denied the EPA’s allegations, saying it “neither condones nor engages in cheating.” In a press release, the company stated they will “vigorously defend itself against the EPA’s allegations.” Cummins has requested a hearing to defend itself against the EPA and review the accusations. The potential $1.5 billion penalty is over six times the amount paid by Volkswagen for its emissions-cheating scandal in 2016. While Volkswagen violated emissions legislation in the United States, Canada, and other countries, Cummins’ violations are limited to the United States. The accusations against Cummins come at an inopportune time. Last year, the company faced a slowdown due to a decrease in demand, resulting in a 30 percent decline in sales. The EPA has said that Cummins’ alleged violations “undermined public health and our environment.” That’s why the organization is going after the major engine manufacturer with the biggest penalty ever imposed under the Clean Air Act. It’s now up to Cummins to prove its innocence and dispute the penalties.