Additional Resources

Clean Diesel And New Ozone Clean Air Standards

The Environmental Protection Agency (EPA) has issued new, more stringent standards (for ozone to help improve air quality across the country, reducing the allowable levels from 0.08 parts per million to 0.075.  Ozone is not usually emitted directly into the air, but at ground-level is created by a chemical reaction between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight. The diesel industry has been reducing emissions of NOx and VOC emissions for over two decades – producing cleaner, more efficient products using cleaner diesel fuel that diesel.

What makes nitrogen oxides?

Nitrogen oxides come from many sources including power plants that generate electricity, driving motor vehicles, industrial processes, gasoline vapors and chemical solvents. According to the most recent EPA data, diesel-powered vehicles are responsible for approximately 30% of all nitrogen oxide emissions and 2.7% of volatile organic compounds. 

Will clean diesel technologies help meet the new standards?

Yes.  Across the board, from passenger cars and highway trucks to the largest earth moving machines, the diesel industry has been working to virtually eliminate the key emissions associated with diesel engines, including nitrogen oxides.  The new ultra-low sulfur diesel fuel coupled with advanced clean burning engines and new emissions controls is a critical part of the overall solution for meeting strict new air quality standards and will help improve the nation’s overall air quality.  Specific improvements include:

• New Light Duty Diesel Cars, SUVs and Light trucks: A new generation of clean diesel cars are arriving to the US beginning this year. These new cars are lower in NOx emissions of earlier diesel engines, and are now meeting the same NOx emissions certification standards as gasoline vehicles, but getting 20 to 40 percent more miles per gallon than a gasoline car. They also have lower emissions of greenhouse gases – carbon dioxide (CO2).
• Heavy-Duty Trucks and Buses – NOx emissions from new heavy-duty diesel trucks and buses have been reduced from a level of 6 grams/bhp-hr 1994 to an average of 1.2 grams/hp-hr in 2007 and will be reduced further to 0.2 grams/bhp-hr by 2010.  According to EPA, NOx emissions from highway vehicles were reduced from 9019 to 6984 short tons between 1994 and 2006; a 22.6 percent reduction.
• Off-Road Equipment
– Similar levels of emissions reduction are phasing in for off-road equipment used in construction, agriculture and mining industries.  For many users, the switch to cleaner lower-sulfur diesel fuel took place in June 2007.  NOx emissions from large construction equipment have already fallen from 9.2 grams/hp-hr in 1997 to 4 grams/hp-hr in 2007 and will further decline to 2.6 grams/hp-hr by 2011.

What about existing diesel engines?

The same clean diesel technologies being used in this new generation of diesel vehicles and equipment is being applied to some older heavy-duty highway engines and off-road vehicles today.    Congress recognized the value and opportunity for modernizing and upgrading diesel engines when it enacted the Diesel Emissions Reduction Act in 2005,  which created a national diesel retrofit program funded at $49.2 million in FY08.  Diesel retrofits have also been funded through the Congestion Mitigation and Air Quality program and Supplemental Environmental Projects