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October 24, 2012   |   Diesel Technology Forum

Press Release

Diesel Technology Forum Statement on the UC-Berkeley Study on Secondary Organic Aerosols

Contact: Steve Hansen (301) 668-7230 shansen@dieselforum.org

Washington, D.C. - The Diesel Technology Forum issued the following statement today regarding the study published this week by the University of California-Berkeley comparing diesel and gasoline emissions. Allen Schaeffer, the Executive Director of the Diesel Technology Forum, issued this statement:

“There have been several studies and reports released this year regarding diesel emissions, including ones by the Health Effects Institute and U.S. Environmental Protection Agency (EPA), that highlighted the extensive advancements in clean diesel technology and dramatically reduced emissions (see below).

“While this UC-Berkeley study concluded that diesel emissions were worse for smog formation than gasoline, a March 2012 study by the National Oceanographic and Atmospheric Administration (NOAA) and Cooperative Institute for Research in Environmental Science (CIRES) found that ‘gasoline emissions were the predominant contributor to the secondary organic aerosol mass’.

“Air quality and public health are important issues that we take very seriously. Atmospheric chemistry is a complex science and it is clear from this and other studies that the science is still evolving and is without a consensus. We intend to continue working with the scientific community to evaluate the science and better understand its implications.

“EPA notes that the formation of PM2.5 from NOx and VOC gases from on-road mobile sources is not a constant value or conversion factor. Many environmental factors are responsible for the conditions that make it favorable or unfavorable for formation of PM2.5 from these compounds.

“While the scientific debate will continue on atmospheric chemistry, there is no debate about the impact of clean diesel technology in terms of air quality and emissions of fine particles. No other sector has done more to improve California’s air quality in the last decade than diesel. According to the California Air Resources Board (ARB), particulate emissions from heavy-duty diesel trucks have declined from 7.5 percent of the overall state inventory in 1990 to 3.8 percent in 2008, and by 2020 it will be just 1.6 percent. The ARB also projects that from 2008 to 2020, while emissions of all sources of PM are expected to increase by 3.2 percent, PM from all diesels will decline by 58 percent.

“These unprecedented reductions in emissions levels are a direct result of the billions of dollars of investments in cleaner fuels and advanced diesel engines and emissions controls to meet the challenges established by the ARB and the U.S. Environmental Protection Agency (EPA). Today clean diesel technology enables new commercial trucks, construction machines and farm equipment to achieve near zero emissions.

“According to EPA, nationwide fine particles from diesel engines now make up less than six percent of the entire particulate emission inventory. Today in California, more fine particles come from brake dust and tire wear than from diesel emissions.

New Diesel Technology Has Reduced NOx By 99% and Particulate Emissions by 98%

“During the past 12 years, emissions from heavy-duty diesel trucks and buses have been reduced by 99 percent for nitrogen oxides (NOx) - an ozone precursor - and 98 percent for particulate emissions to meet California and EPA requirements, making them near-zero emissions vehicles. Off-road engines and equipment are now in the final phase of the same transition. Critical to this progress has been the availability of ultra-low sulfur diesel (ULSD) fuel, which has reduced sulfur emissions by 97 percent – from 500 PM to 15 PM - enabling advanced emissions control devices.

“Today new diesel engines are near zero emissions in highway trucks with off-road machines and equipment on a similar path by 2014.”

2012 Research Highlights How Clean Diesel Technology Has Significantly Reduced Emissions

Several 2012 scientific and academic research studies have highlighted the important advancements in clean diesel technology:

- In a special presentation on May 24, 2012 to the California Air Resource Board in Sacramento, California, leading international scientists discussed the key short-lived agents black carbon (soot) and methane. Findings presented to the ARB indicated a 50 percent reduction of black carbon in ambient air over the past 20 years. Mary Nichols, Chairman of the ARB stated: “It is encouraging to see that ARB’s diesel regulations, while designed to improve public health are also addressing climate change.”

- A new study released on April 12, 2012 by the Health Effects Institute (HEI) provides important new insights into the emissions and health effects of the new diesel, known as the Advanced Collaborative Emissions Study (ACES). These and related findings were recently presented at a CARB Research Seminar.

- In its March 2012 Report to Congress on Black Carbon (BC), the EPA stated: “[T]he United States will achieve substantial BC emissions reductions by 2030, largely due to controls on new mobile diesel engines.“ The EPA report also recognizes the challenges in reducing emissions from both mobile and stationary diesel engines in these developing countries since they typically do not have ready access to cleaner low sulfur fuels that are required for most advanced emissions control technologies.

- New research released April 23, 2012 from North Carolina State University - “Real-World Measurement and Evaluation of Heavy Duty Truck Duty Cycles, Fuels, and Emission Control Technologies” - shows that federal requirements governing diesel engines of new tractor trailer trucks have resulted in major cuts in emissions of particulate matter (PM) and nitrogen oxides (NOx). Trucks in compliance with newer standards showed a 98 percent decrease in NOx and 94 percent reduction in PM emissions.


The Diesel Technology Forum is a non-profit national organization located in the Washington, D.C. area that is dedicated to raising awareness about the importance of diesel engines, fuel and technology. Forum members are leaders in clean diesel technology and represent the three key elements of the modern clean-diesel system: advanced engines, vehicles and equipment, cleaner diesel fuel and emissions-control systems. For more information visit www.dieselforum.org.

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