Release 04-07      
March 25, 2004 


Jerry Martin
Gennet Paauwe
(916) 322-2990
ARB Requires Lower Emissions from In-Use Big-Rig Trucks

       SACRAMENTO --  The California Air Resources Board (ARB) today approved a plan to accelerate upgrades of emission control software that reduce excess smog and particulate-forming nitrogen oxide (NOx) emissions from most heavy-duty diesel trucks, buses and recreational vehicles (RVs) built between 1993 and 1999.

    ARB Chairman Dr. Alan Lloyd said, "These trucks have been emitting unnecessarily high emissions for too long, and neither hard working California truckers nor the rest of our citizens deserve to be exposed to this pollution any longer.  There are steps that can be taken now to reduce this pollution, and the plan we adopted today will do just that."

    The unique rulemaking stems from a 1998 legal settlement between the ARB, the U.S. Environmental Protection Agency (USEPA) and the nation's six biggest diesel manufacturers: Caterpillar, Cummins, Detroit Diesel, Mack/Renault, Navistar and Volvo.  ARB and USEPA showed that those manufacturers used defeat devices, software that caused high emissions under certain modes of operation.  One provision of the settlement required engine manufacturers to develop low emission software that could be installed to reduce the emissions of these trucks.  The new software has no effect on a vehicle's operation.

    The ARB's new plan will result in low emission software installed much sooner than is occurring under the legal settlement.  Engine manufacturers agree to pay for the software and its installation any time a truck visits a dealership.  The goal of the voluntary plan is to increase the percentage of California vehicles using low emission software from the current level of 10 percent to 35 percent by November 2004, 60 percent by June 2005, 80 percent by February 2006 and 100 percent by 2008.  If those targets are not met, the ARB will implement a regulation requiring the upgrades.

    As part of the 1998 settlement, manufacturers agreed to upgrade the computer software when vehicles were brought into repair shops for rebuilding, presumably between 300,000 and 400,000 miles.  Many of those vehicles have now been operating for more than 700,000 miles without rebuilding and therefore are exposing the public to many times their intended pollution output.

    According to ARB data, more than 60,000 heavy-duty vehicles still operating with defeat devices are licensed in California, with another 300,000 to 400,000 vehicles from other states operating part-time in California each year.  Those data also show that less than 10 percent of all eligible vehicles have been upgraded since 1998.  Combined, those vehicles emit more than 30 tons of excess NOx daily, the pollution equivalent of over one million cars.

    "This plan will quickly reduce nitrogen oxide emissions from heavy-duty diesel trucks and buses by accelerating the use of effective emission control software.  Control of these emissions is essential if we are going to continue to reduce ozone and particulate concentrations in California's air," Lloyd added.

    The Air Resources Board is a department of the California Environmental Protection Agency.  ARBís mission is to promote and protect public health, welfare, and ecological resources through effective reduction of air pollutants while recognizing and considering effects on the economy.  The ARB oversees all air pollution control efforts in California to attain and maintain health based air quality standards.

 The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. For a list of simple ways you can reduce demand and cut your energy cost, see our web site at

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