Local Emissions Studies

Learn about special purpose emissions studies in the Bay Area and view information about recent studies.

On occasion, the Air District conducts short-term emissions studies in the Bay Area to:

  • Improve the accuracy of emissions estimates
  • Assess the benefits of emissions reduction measures
  • Produce emissions for local-scale air pollution assessments

View information about recent emissions studies below.

Drayage Truck Study at the Port of Oakland

The Air District partnered with UC Berkeley and the Lawrence Berkeley National Laboratory to measure emissions from drayage trucks before, during, and after a new emissions rule was implemented.

During a set of monitoring campaigns from 2009 to 2013, researchers documented significant emissions reductions from trucks serving the Port of Oakland.  During this period, the fraction of trucks equipped with a diesel particle filter at the Port of Oakland increased from 2 to 99%, and the median engine age decreased from 11 to 6 years. Similarly, the average emission rate decreased 76% for black carbon and 53% for nitrogen oxides. Initial study results were published in Environmental Science & Technology.

Caldecott Tunnel Truck Study

Beginning summer 2014, the Air District supported a California Air Resources Board study at the Caldecott Tunnel to measure the emissions benefits of CARB’s Truck and Bus Regulation.

Researchers from the Lawrence Berkeley National Laboratory and UC Berkeley are using the Air District’s mobile sampling van to measure emissions from on-road, heavy-duty trucks at three stages of implementation of the new regulation:

  1. 2014 – When a significant portion of trucks will be equipped with diesel particle filters.
  2. 2015 – When pre-1994 engines will have been replaced with 2010 and newer engines.
  3. 2017 – When pre-1996 engines will have been replaced with 2010 and newer engines.

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The Air District mobile sampling van is used to sample truck plumes from above the west entrance to the Caldecott Tunnel (2014).

Caltrain Passenger Train Study

During summer 2014, the Air District sponsored a study to measure black carbon emissions for in-use, diesel-electric passenger trains in the Caltrain fleet, which operates along the San Francisco peninsula between San Francisco and Gilroy. The Caltrain fleet will be converted to electricity in 2019, so this study provides an opportunity to estimate emissions benefits of electric passenger trains. This study also provides an opportunity to compare emissions from in-use sources with federal emissions standards, as many of Caltrain’s engines have been overhauled to reduce emissions. The results of this study will be published in a report.

Methane Emissions Study

Several recent studies suggest that national and regional methane emission estimates have been underestimated by 50 to 100 percent. Understanding why methane emissions have been underestimated is essential to developing effective greenhouse gas control measures.

In partnership with Lawrence Berkeley National Laboratory researchers, the Air District conducted a study to evaluate and improve methane emission estimates in the Bay Area. This study built on previous work in which methane emissions maps were developed for each major source sector in the state. The researchers evaluated the Air District’s current emissions inventory, revised the methane emission maps with better precision for the Bay Area, and suggested ways to improve emission estimates.

Commercial Maritime Seaport Inventories

In 2006, the Air District, California Air Resources Board, and Port of Oakland began a multi-year collaborative study to estimate public health risks from exposure to diesel emissions in West Oakland. Researchers assessed diesel exhaust emissions from three key sources:

  1. Maritime Port of Oakland
  2. Union Pacific rail yard
  3. West Oakland community sources, such as non-port marine vessels and trucks

The Air District and Bay Planning Coalition partnered to prepare a maritime emissions inventory for four Bay Area public ports. Researchers followed methodologies used for the Port of Oakland’s 2005 seaport air emissions inventory to ensure a consistent set of inventories for the region’s public ports.

Commercial maritime seaport emissions inventories were produced for the following ports:

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Last Updated: 4/6/2022