According to the Environmental Protection Agency (EPA), transportation sources emitted 29 percent of all greenhouse gas (GHG) emissions in the U.S. in 2007 and have been the fastest-growing source of GHG emissions in the country since 1990. Heavy-duty vehicles are the fastest-growing contributors to GHG emissions, the EPA adds, with Class 7 and 8 combination tractors and their engines accounting for roughly two-thirds of total GHG emissions and fuel consumption from the heavy-duty sector.
The EPA rang in the new millennium with an event horizon for diesel engine emissions and mandated that, effective with the 2007 model year, exhaust emissions spewing from on-highway truck engines be reduced by more than 90 percent.
Also beginning with the 2007 model year, all on-road diesel heavy-duty engines were required to be outfitted with a diesel particulate filter and another 50 percent of engines required nitrogen oxide (NOx) exhaust control technology.
By the 2010 model year, all on-road heavy-duty diesel engines were required to have NOx exhaust control technology.
The beginning of an era
Commonly referred to as EPA 2010, these new government emission standards focused on reducing pollutants, NOx and particulate matter (PM) coming from heavy truck engines to .2 gram per brake horsepower hour for NOx and .01 for PM.
