A lone mechanic may have contributed to furthering vehicle emissions pollution, with a device he created that helped thousands of vehicles bypass emission controls, market watch reports. Those vehicles would go on to pollute hundreds of times more than the legal limit.

Mechanic Matthew Sidney Geouge, of Hendersonville, NC, ran his emissions operation for over 10 years at his company, Spartan Diesel Technologies. Federal authorities claim that Geouge advertised devices would help increase engine performance in diesel trucks. He sold over 14,000 devices, making over $10 million.

According to authorities, Geouge’s tuners or “tunes” were tailored to maximize engine power, which in significant increases in harmful air emissions. Some of the drivers who purchased this performance enhancing service, ended up noticing and reporting that they were actually decreasing performance.

Geouge was warned numerous times over the years to stop selling the devices, but never did. The first warning came in 2015 when the EPA issued a stop-sale citation. Just two years later, the EPA hit him with a $4 million fine, which in him selling Spartan Diesel Technologies. It gets better because of course Geouge was also not filing taxes. The IRS says he didn’t file between 2015 and 2019.

After pleading guilty in the case against him for tax evasion and violating the Clean Air Act, Geouge faces three supervised years of release, six months of home confinement, a $1.3 million penalty to the EPA, and $1.2 million in restitution to the IRS. Three of his conspirators all received the same probation and home sentences as well as fines ranging from $10,000 to $150,000