Study shows dramatic reductions in diesel engine emissions

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A new study shows that clean diesel technologies in engines manufactured beginning in 2007 not only reduced certain emissions by 90 percent over 2004 models, but far exceeded expectations in their performance in cleaning up the nation’s air quality.

Emissions reductions by 2007 model engines “exceeded substantially even those levels required by law,” said the study, conducted by the Coordinating Research Council and the Health Effects Institute. Current engine models produced 98 percent less carbon monoxide, 10 percent less nitrogen oxide, 95 percent less non-methane hydrocarbons and 89 percent less particulate matter than required by the U.S. Environmental Protection Agency’s 2007 diesel engine emissions standards.

“Diesel engines are the workhorses of the nation’s transportation infrastructure because they are fuel-efficient, durable and reliable,” says Jed Mandel, president of the Engine Manufacturers Association. “We can now add near-zero emissions to the list of diesel’s positive attributes.”

The study, sponsored by a multiparty group of government and industry organizations — including EPA, the U.S. Department of Energy, the California Air Resources Board and the Engine Manufacturers Association — is phase 1 of the Advanced Collaborative Emissions Study (ACES). This five-year comprehensive emissions testing program will test the emissions and health effects of new technology diesel engines to document the improvements that have been made and to ensure that there are no unintended emissions from these new technologies. The results of the ACES study can be found by going to

“These latest emissions figures are a testament to the trucking and engine manufacturing industries’ deep commitment to the environment,” says Bill Graves, American Trucking Associations president and chief executive officer. “We’re proud of the significant progress that has been made, and we look forward to building upon this foundation as we continue to work toward a more sustainable future.”

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