Good News in Clean Air Versus Vehicle Traffic

Aug. 2, 2001
The news about clean air versus vehicle traffic isn't all bad. Despite a 75% growth in the gross domestic product and a 72% increase in vehicle miles

The news about clean air versus vehicle traffic isn't all bad. Despite a 75% growth in the gross domestic product and a 72% increase in vehicle miles traveled, emissions of particulate matter fell by 55% over the past 18 years, according to the Diesel Technology Forum (DTM), Washington DC.

From 1980-1998, while the population increased 19%, real gross domestic product (GDP) increased by 75%, and vehicle miles traveled (VMT) increased 72%, while at the same time emissions of particulate matter fell by 55%. In addition, emissions of nitrogen oxides increased by just one percent.

The DTM was created by companies in diesel technology, engine, vehicle, and fuel systems manufacturing, and petroleum refining. The purpose of the organization is to create a new dialogue and encourage the full exchange of information and views on a full range of issues concerning today's diesels and tomorrow's diesel technologies.

"The US has made tremendous strides in reducing emissions while at the same time experiencing extraordinary economic growth," said Allen Schaeffer, executive director of The Diesel Technology Forum. "During this time -- more diesel engines were in use and new engines purchased in the transportation sector than ever before. Diesel engines are the backbone of the nation's transportation system -- powering the overwhelming majority of all commercial trucks, freight locomotives, transit buses and commercial marine vessels. The progress the diesel industry has made has been nothing short of extraordinary."

According to the latest available data from the Environmental Protection Agency (EPA), on average, diesel engines account for only 7.21% of regulated emissions from all sources. Specifically, diesel emissions (from all sources-on road and off-road) account for:

-- 3.3% of carbon monoxide emissions.

-- 3.77% of volatile organic compounds (VOCs) or


-- 5.75% of sulfur dioxides.

-- 1.49% of particulate matter less than 10 microns (PM-


-- 5.56% of all particulate matter smaller than 2.5 microns (PM2.5).

-- 30.38% of nitrogen oxides.

-- 0.20% of all ammonia emissions.

Of the five major emissions from internal combustion engines (carbon monoxide, hydrocarbons, carbon dioxide, nitrogen oxide and particulate matter), diesel emits only a small amount of the first three, according to DTF.

The focus of the industry has been to reduce particulate matter and nitrogen oxides. Particulate matter emissions from all new on-highway diesel engines built since 1988 have been reduced 83%. Emissions of nitrogen oxides have been reduced by 63% since 1988 and new engine standards for 2004 will cut those emissions in half again, resulting in a total reduction of 83% of oxides of nitrogen since 1988.

Regulations adopted by the EPA for 2007-2010 will require the use of cleaner diesel fuel that will enable the further lowering of nitrogen oxides and particulate matter. The emissions are slated to be reduced by as much as 98% from the 1988 levels, virtually eliminating these emissions from on-highway engines. Critical to achieving these reductions will be the introduction of cleaner diesel fuel.

"The degree and nature of these technological innovations put today's diesel engines on par with advancements in today's interactive web sites, wireless communications, and fiber optics" said Schaeffer. "These innovations have been key to achieving society's energy and environmental goals."

A report from DTM has further information about the issue. Copies of the report can be found at .>