A new report released by the Puget Sound Maritime Air Forum highlights a continued decrease in maritime-related air pollutant emissions across the Puget Sound region, through 2021. The Puget Sound Emissions Inventory (PSEI) report, compiled through a collaborative effort involving seven ports, six government agencies, and three industrial partners, reveals reductions in emissions across various maritime sectors when compared to data from 2016 and 2005.

Key findings from the PSEI reveal an 82 percent reduction in diesel particulate matter and a 10% decrease in greenhouse gas emissions from port and maritime sources throughout the greater Puget Sound area from 2005. These positive trends reflect the collective commitment to environmental stewardship demonstrated by Puget Sound ports, government entities, and the maritime industry at large.

The decline in emissions is attributed to strategic investments in electrification, cleaner engine technologies, operational efficiencies, and the implementation of the North American Emissions Control Area regulation, which requires vessels to burn lower sulfur fuels while within 200 miles of shore.

The PSEI is conducted every five years, and the most recent inventory in 2021 came during an unusual year for the maritime industry in the wake of the COVID-19 pandemic. Supply chain disruptions worldwide impacted shipping at Puget Sound ports, leading to changes in cargo throughput, and increased the amount of time ships spent in port and at anchor than in previous years. 2021 also had a smaller cruise season at Port of Seattle after the full shutdown in 2020.

“As ports, we hold a pivotal role in driving economic activity while prioritizing environmental sustainability in the Puget Sound region. The Puget Sound Emissions Inventory is an important tool to identify how our policy decisions and investments are helping to reduce air and climate pollution from port operations while also identifying key areas of improvement that we must focus on in the coming years,” stated Kristin Ang, Port of Tacoma Commission President and The Northwest Seaport Alliance Co-Chair.

The PSEI was established in 2005 to set a baseline understanding of maritime and port related emissions that would inform the development of emission reduction programs. Subsequent inventories every five years are critical for tracking progress and redirecting emission reduction efforts as necessary. The inventory assesses a range of pollutants that impact air quality and climate change, including nitrogen oxides (NOx), volatile organic compounds (VOC), sulfur dioxide (SO2), diesel particulate matter (DPM), black carbon (BC), and greenhouse gases (CO2e), associated with ships, harbor vessels, cargo-handling equipment, rail, heavy-duty trucks, and other fleet vehicles engaged in maritime activities.


“The Port of Everett is committed to greening the supply chain and reducing our carbon footprint. With over $150 million invested in Seaport modernization in recent years, we've achieved diverse environmental benefits and advanced our climate change strategy. During the pandemic supply chain crisis, we handled excess cargo with lower emissions per unit—delivering cargo with a lower carbon footprint than any past inventories. We look forward to continuing this important work in Everett and the Puget Sound”, stated Lisa Lefeber, Port of Everett CEO.

The initial inventory conducted in 2005, followed by updates every five years (2005, 2011, 2016, 2021), has served to monitor efforts to reduce emissions over time and ensure the accuracy and transparency of emission estimates. This voluntary initiative provides a strong technical foundation for future environmental programs, initiatives, and policy decisions.

 “This latest Puget Sound Emissions Inventory demonstrates the extraordinary progress we have made in reducing emissions and improving efficiency at our seaports.   These results confirm that the investments in clean air that are being made by the marine terminal and ocean carrier members of the Pacific Merchant Shipping Association (PMSA) have been exceptionally effective.  As a founding member of the Maritime Air Forum, PMSA continues to support these air emissions inventories because the data in these inventories show exactly how impressive our emissions reductions in several key areas have been, and also where we still have work to do,” said Capt. Mike Moore, PMSA Vice President

The inventory results will be used to help guide and focus future emissions reduction efforts and investments, including further community outreach in areas historically disproportionately impacted by air pollution. These efforts align with the Northwest Ports Clean Air Strategy, a collaborative initiative among The Northwest Seaport Alliance, Port of Seattle, Port of Tacoma, and the Port of Vancouver, B.C., aimed at achieving zero maritime emissions by 2050 or earlier.

“This level of scientific and detailed calculations creates the opportunity for the greatest emission reductions possible. It’s wonderful to be part of such a coordinated effort, and we are eager to maintain this partnership as we implement the Northwest Port Clean Air Strategy for air quality benefits here, and climate damage mitigation globally,” stated Christine Cooley, Executive Director, Puget Sound Clean Air Agency

“The Ports and the NW Seaport Alliance are committed to reducing the impacts of maritime emissions on communities and the climate. We’re proud of the significant reductions in maritime emission we’ve made to date, but recognize we’ll still need to make major investments to achieve our zero-emission goal. We greatly appreciate the significant sources of funding made available by recently passed state and federal legislation which, along with our industry, labor and government partners will go a long way toward decarbonizing the supply chain,” stated Port of Seattle and The Northwest Seaport Alliance Commissioner Fred Felleman.

Find more information about the emissions inventory and its results at

The full press conference is available here




Puget Sound Air Emissions Inventory

About the Port of Everett
The Port of Everett is a special-purpose district tasked with economic development. Through operation of international shipping terminals, the largest public marina on the West Coast and real estate development ventures, the Port of Everett supports nearly 40,000 jobs in the region and contributes $433 million to state and local taxes. The Port strives to bring quality jobs, business and tourism opportunities to its local and surrounding communities, and is committed to enhancing, restoring and preserving the overall environmental health of the waterfront. Port properties provide numerous public access and recreational opportunities for area residents and visitors to enjoy, supporting a vibrant, livable and balanced waterfront. Learn more at

In a historic action on Dec. 19, 2023, the Port Commission unanimously passed Resolution No. 1220, directing Port staff to submit a proposition of enlarging the limits of the existing Port District to the Snohomish County Council for voter consideration – a first since the citizens voted to create the Port over a century ago in 1918. The measure, slated for the August 2024 primary ballot, will consider enlarging the Port District to all of Snohomish County, excluding City of Edmonds, Port of Edmonds and Town of Woodway limits, respectively. Learn more at

About The Northwest Seaport Alliance