California Air Resources Board

SACRAMENTO - A study funded by the California Air Resources Board demonstrates that mandatory upgrades to diesel truck fleets serving the Port of Oakland are responsible for significant reductions in two major air pollutants.

According to research conducted by Berkeley scientist Robert Harley and based on data collected from thousands of trucks near the Port of Oakland, emissions of black carbon, a key component of diesel particulate matter and a pollutant linked to global warming, was slashed 76 percent from 2009 to 2013. Emissions of oxides of nitrogen, which leads to smog, declined 53 percent.  Also during this period, the median age of truck engines declined from 11 to six years, and the percentage of trucks equipped with diesel particulate filters increased from 2 percent to 99 percent.

Dr. Harley will elaborate on these results during an ARB-hosted research seminar and webcast open to the public at 1:30 pm (PDT) on Thursday, June 18.  More information can be found here. The webinar will be archived on ARB’s website.

The study findings are considered dramatic because they occurred over a relatively short time. Comparable emissions reductions could normally take up to a decade through gradual replacement of old trucks or natural fleet turnover.

In this case, the improvements are attributed to the ARB’s Drayage Truck Regulation and to the Comprehensive Truck Management Program at the Port of Oakland, which require vehicle owners serving the port to clean up their trucks by either replacing them with newer models or installing diesel particulate filters.

Diesel trucks are one of California’s biggest sources of air pollution. Because they are so durable, they can operate for decades and emit significant amounts of diesel pollution unless they are retrofit with filters or replaced.

Adopted in 2007, the ARB’s Drayage Truck Regulation requires all trucks serving major California ports and intermodal rail yards to be registered and upgraded according to a staggered implementation schedule. By Jan. 1, 2023, all class 7 and 8 diesel-fueled drayage trucks must have 2010 or newer engines. Currently, pre-2007 model year (MY) trucks cannot serve the ports.  All 2007-2009 MY trucks are compliant through 2022.

Diesel exhaust contains a variety of harmful gases and more than 40 other known cancer-causing compounds. In 1998, California identified diesel particulate matter as a toxic air contaminant based on its potential to cause cancer, premature death and other health problems.