Update: Impacts of Heavy-Duty Diesel Truck Emissions

UC Berkeley and Berkeley Lab researchers received notable selection from the American Chemical Society for their recent publication “Control Technology-Driven Changes to In-Use Heavy-Duty Diesel Truck Emissions of Nitrogenous Species and Related Environmental Impacts,” in Environmental Science and Technology. Together, Chelsea Preble, Robert Harley and Thomas Kirchstetter conducted several comprehensive studies of pollutant emissions from heavy-duty diesel trucks en route to the Port of Oakland and on Highway 24.

Heavy-duty diesel trucks are essential for the movement of goods in California and the nation, but they contribute significantly to the burden of diesel particulate matter and nitrogen oxides in the air. Nitrogen oxide emissions are linked to significant health impacts, can exacerbate asthma attacks, and undergo chemical reactions in the atmosphere, leading to the formation of particulate matter and ozone. Exposure to particulate matter is associated with cardiovascular and respiratory diseases and premature death. 

To address health and environmental concerns, statewide regulations from the California Air Resources Board (CARB) have led to the accelerated adoption of modern emission control systems—diesel particle filters (DPFs) and selective catalytic reduction (SCR) systems—by requiring retrofit or replacement of older engines on heavy-duty diesel trucks. The research team set out to quantify the changes in emissions caused by the use of modern emission control systems on heavy-duty diesel trucks. 

“Our study allows us to understand the actual performance of these technologies rather than assumed performance that might be based on the certification of new trucks. It also provides the State with an independent assessment of air pollution benefits of its regulations,” said Kirchstetter. 

The research team found large reductions in emissions of nitrogen oxides and black carbon, a major constituent of diesel particulate matter commonly known as soot. The team also measured increases in other pollutants, including ammonia, a precursor to atmospheric formation of particulate matter, and nitrous oxide, a potent greenhouse gas. “Overall, we found that DPF and SCR systems lead to a large net-decrease in the social cost of statewide exposure to diesel truck emissions, where social cost is a metric of particulate matter exposure-attributed premature mortality,” said Preble. The net impact on global warming potential-weighted emissions was small, due to offsetting decreases in warming black carbon emissions and cooling nitrogen oxides emissions. 

Preble is a postdoctoral researcher at UC Berkeley and affiliate of Berkeley Lab; Harley is a professor at UC Berkeley and a faculty scientist at Berkeley Lab. Kirchstetter is an adjunct professor at UC Berkeley and a senior scientist and division director at Berkeley Lab. This study was supported by CARB and the Bay Area Air Quality Management District.

Read the publication here: pubs.acs.org/doi/full/10.1021/acs.est.9b04763