After conducting thorough environmental assessments, Lawrence Berkeley National Laboratory has found that California's diesel truck regulations to reduce air pollutants have been successful.
While the U.S Environmental Protection Agency (EPA) sets emissions standards for new truck engines, there are many older trucks and buses on the road, which do not fall under the new EPA rules. California responded to this gap in legislation by regulating older trucks and buses with two pieces of technology: diesel particle filters, responsible for removing particulate matter from emissions, and selective catalytic reduction, targeting the emission of nitrogen oxides.
These regulations are having a positive effect on air pollution in the area. Phil Martien of the Bay Area Air Quality Management District (BAAQMD) stated, "At the Port of Oakland, we measured dramatic reductions of nitrogen oxides and black carbon PM, indicating a large degree of success which should translate into local improvements in air quality, especially as more trucks on the road use these technologies."
Another study, led by the Scripps Institution of Oceanography at the University of California, San Diego, and funded by the California Air Resources Board found that carbon dioxide emissions have been reduced by 21 million metric tons annually, which is the equivalent of removing more than 4 million cars from state roads each year.
The mechanics demanded by the regulations do have some unfortunate side effects, causing increased emissions of certain noxious nitrogen oxides, while decreasing other pollutants. Nevertheless Thomas Kirchstetter, a scientist with the Lawrence Berkeley National Laboratory, emphasized the importance of regulations like the ones in California. "The technologies we're evaluating will eventually dominate truck fleets nationwide, so the significance of our study extends far beyond California," he stated.
Research teams are working on decreasing the impact of any adverse effects of emission reduction technologies.