CARB study shows truck emissions devices are rarely tampered with

| 9/7/2007

Truckers in California rarely tamper with emissions devices such as diesel particulate filters or ECMs, according to a recent study commissioned by the California Air Resources Board.

Thomas Durbin of the University of California-Riverside revealed results of a study regarding malfunctions, tampering and in-use emissions for heavy duty diesel trucks at a CARB Chair’s Air Pollution Seminar presented Wednesday, Sept. 5.

The study surveyed maintenance shops and CARB enforcement’s roadside inspection statistics and found that less than 1 percent of the trucks surveyed showed evidence that their emissions technology had been tampered with.

To read the presentation, click here.

The study also used CARB’s mobile emissions laboratory, a trailer that hooks up exhaust tailpipes to machines for measurements of nitrogen oxides and diesel particulate matter among five tractors powered by engines manufactured by Cummins, Caterpillar, Detroit Diesel Series and Mack.

The test sent the trucks through surface streets and two highways around Stockton, CA, finding that some of the trucks emitted more NOx for higher speeds while others didn’t. Also, on surface street driving, the truck with the oldest engine tested had the most particulate matter emissions, while on highway driving the two newest trucks had the highest PM emissions.

Predictably, the study concluded that the oldest truck, a 1996 truck with a Cummins model engines, emitted the most pollutants for most driving categories.

– By Charlie Morasch, staff writer