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New Report Finds Diesel Smoke Testing Programs Effective

"These cost-effective programs are win-win-better for the environment because they reduce excess emissions, and better for the operators, since visible smoke emissions means unburned fuel (and dollars) going out the smokestack," said Allen Schaeffer, executive director of DTF. States without these programs are missing cost-effective opportunities for reducing emissions and getting gross emitters off the road. Roadside smoke testing programs are particularly effective because they specifically target and test trucks on the road that are visibly poorly maintained. Fleet operators not doing their fair share for clean air can and should be targeted to clean up their engines," added Schaeffer.

Substantial progress has been made over the last decade in reducing emissions from heavy-duty diesel engines used in trucks and buses. Today's highway truck or bus engine is 8 times lower in emissions of particulates and nitrogen oxides than the same engine that is 12 years old. Diesel engines have been free of visible smoke for 10 years. Despite these improvements, a fraction of older vehicles on the road today are improperly maintained or maladjusted, causing them to emit excessive smoke and other pollutants. In order to identify, test and repair such vehicles, heavy-duty diesel vehicle emission inspection programs have been initiated in a number of locations in the United States and Canada. State Diesel Emission Inspection Programs: Trends and Outcomes is the first effort to estimate the emission benefits of diesel inspection programs and compare available data across programs.

Other key findings of the report:

• Smoke inspection programs are effective in reducing both the number of very smoky vehicles and the average smoke opacity from the vehicles.
• Approximately 5-7 percent of pre-1998 vehicles have smoke emissions that exceed standards.
• 1998 and newer vehicles have significantly lower smoke emissions than pre-1998 vehicles partly due to improved engine technology.
• The EPA-endorsed test procedure - the snap acceleration test (SAE J1667) remains an effective test procedure.

To view or download a copy of the complete report, and other tools and information on state diesel emissions inspection programs, go to www.dieselforum.org.

The report was compiled for the Diesel Technology Forum by Energy and Environmental Analysis, Inc. of Arlington, VA.

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The Diesel Technology Forum represents engine makers, fuel producers and emissions control manufacturers. It brings together the diesel industry, the broad diesel user community, civic and public interest leaders, government regulators, academics, scientists, the petroleum industry, and public health researches, to encourage the exchange of information, ideas, scientific findings, and points-of-view to current and future uses of diesel power technology. For more information about the Forum visit our web site at www.dieselforum.org.