Emissions & Controls

Vehicle Air Pollution Emission Control Technologies

We characterize pollutant emissions from in-use vehicles to quantify how new and evolving emission control technologies alter pollutant emissions over time, providing an independent assessment of state and federal emission control programs that aim to clear the air.

Emissions & Controls

Quantifying In-Use Emissions and the Impact of Controls

Tom Kirchstetter, Chelsea Preble conduct experiment outside of Caldecott Tunnel in the Bay Area
Researchers Tom Kirchstetter and Chelsea Preble conduct experiment outside of Caldecott Tunnel in the Bay Area.

Diesel trucks play an essential role in the movement of goods to consumers across our nation. However, diesel engines are major emitters of air pollutants, including nitrogen oxides and black carbon soot.  

To reduce these emissions and their associated adverse impacts on human health and the environment, the Environmental Protection Agency (EPA) establishes increasingly stringent federal emissions standards. To comply with the most recent standards, manufacturers equip new heavy-duty diesel trucks sold in the United States with diesel particle filters and selective catalytic reduction systems.

Lawrence Berkeley National Laboratory (Berkeley Lab) and University of California, Berkeley (UC Berkeley) scientists work together to lead research in measuring the in-use emissions of heavy-duty diesel trucks and the performance and durability of these after-treatment emission control technologies.

Berkeley Lab also researches the effectiveness of vehicle inspection and maintenance programs in reducing emissions from other vehicle types.

The California Air Resources Board and the Bay Area Air Quality Management District support this work.

Research Projects

Measuring Emission Control Technologies' Impacts on Heavy-Duty Diesel Truck Emissions

In this work, a novel remote sensing technology takes a snapshot of several pollutants’ emission rates for each passing truck, including nitrogen oxide, nitrogen dioxide, nitrous oxide, and black carbon. Researchers track the change in these emission rates over time at many locations to understand how emissions change with the introduction of new emission control technologies.

Emissions from thousands of in-use heavy-duty diesel trucks were sampled at a highway and an arterial street location in the San Francisco Bay Area, spanning a period when the use of diesel particle filters and selective catalytic reduction increased rapidly.

Selective catalytic reduction systems installed on 2010 and newer engines reduce emitted nitrogen oxides relative to pre-2004 engines but increase emissions of nitrous oxide and ammonia, respectively. Emissions of all nitrogenous species and especially NH3 are skewed; 10% of trucks contribute 95% of the on-road fleet’s total NH3 emissions. The emission changes due to the rapid adoption of diesel particulate filters and selective catalytic reduction systems by the California truck fleet result in an estimated 65% net decrease in the social cost of statewide exposure to diesel truck emissions and a 3% net decrease in the global warming potential-weighted emission factor.

See article "Update: Impacts of Heavy-Duty Diesel Truck Emissions" for more research efforts in this area.

Characterizing On-Road Emissions from Light-Duty Vehicles

Berkeley Lab analyzes data from vehicle emissions inspection and maintenance (I/M) programs managed in several states. The data include I/M test and on-board diagnostic scan results, remote sensing measurements, roadside pullover test results, and vehicle registration records. We have used the data to analyze various aspects of the effectiveness of inspection and maintenance programs in Arizona; California; Colorado; and Ontario, Canada; including estimated emission reductions, repeat failure rates, and aspects of motorist non-compliance with program requirements. The data also provide a rich resource to understand the distribution of in-use vehicle emissions by location and vehicle type and age.

Collaborations and Partnerships

Bay Area Air Quality Management District (Air District)

The California Legislature created the Air District in 1955 as the first regional air pollution control agency in the country. The Air District is tasked with regulating stationary sources of air pollution in the nine counties that surround San Francisco Bay: Alameda, Contra Costa, Marin, Napa, San Francisco, San Mateo, Santa Clara, southwestern Solano, and southern Sonoma counties. It is governed by a 24-member Board of Directors composed of locally elected officials from each of the nine Bay Area counties, with the number of board members from each county being proportionate to its population.

The Board oversees policies and adopts regulations for the control of air pollution within the district. The Board also appoints the Air District’s Executive Officer/Air Pollution Control Officer, who implements these policies and gives direction to staff, as well as the District Counsel, who manages the legal affairs of the agency. The Air District consists of over 340 dedicated staff members, including engineers, inspectors, planners, scientists, and other professionals.

See more information about the district's work in measuring air quality at the Air District's website.

California Air Resources Board (CARB)

CARB is charged with protecting the public from the harmful effects of air pollution and developing programs and actions to fight climate change. From requirements for clean cars and fuels to adopting innovative solutions to reduce greenhouse gas emissions, California has pioneered a range of effective approaches that have set the standard for effective air and climate programs for the nation and the world.

Research sponsored by CARB

Strong science is at the foundation of California’s air quality and climate programs. The California Air Resources Board sponsors a comprehensive research program that investigates air pollution’s causes, effects, and solutions. The findings of this research support all the regulations on cars, trucks, fuels, power plants, and other pollution sources. The research, which results in five additional dollars for each dollar CARB invests, is done under the guidance of CARB’s Research Screening Committee and in partnership with the campuses of the University of California system and other research institutions.

CARB develops and conducts policy-relevant in-house and extramural research to advance the science and to support CARB mobile source programs and policies. Current research includes efforts to better understand the discrepancy between certification and real-world emission levels, achieve further emission reductions from on-road vehicles and off-road equipment, track and model the effect of various regulatory options to achieve real-world emission reduction targets using laboratory, portable emissions monitoring systems (PEMS), remote-sensing, and engine and activity data-logging technologies, and understand non-tailpipe emissions such as brake-wear, tire-wear, and resuspended roadside dust. CARB is also responsible for programs to reduce emissions of high global warming potential greenhouse gases from mobile air conditioners and to investigate the effect on emissions from advanced vehicle and low-carbon fuel technologies. Some activities include conducting large data-driven technical analyses, providing expert opinions to decision-makers, networking with internal, national, and international stakeholders, and publishing research findings.

Transportation Initiative Lead Scientist
Postdoctoral Researcher

Selected Publications

Preble, CV; Harley, RA; Kirchstetter, TW (2019) Control Technology-Driven Changes to In-Use Heavy-Duty Diesel Truck Emissions of Nitrogenous Species and Related Environmental Impacts, Environ. Sci. Technol., doi:10.1021/acs.est.9b04763 (pubs.acs.org/doi/10.1021/acs.est.9b04763)

Preble, CV; Cados, TE; Harley, RA; Kirchstetter, TW (2018) In-use performance and durability of particle filters on heavy-duty diesel trucks, Environ. Sci. Technol., doi: 10.1021/acs.est.8b02977 (pubs.acs.org/doi/abs/10.1021/acs.est.8b02977?af=R)

Preble, CV, Dallmann, TR; Kreisberg, NM; Hering, SV; Harley, RA; Kirchstetter, TW (2015) Effects of particle filters and selective catalytic reduction on heavy-duty diesel drayage truck emissions at the Port of Oakland, Environ. Sci. Technol., doi:10.1021/acs.est.5b01117 (Effects of particle filters PDF)