It's common knowledge that more traffic means more air pollution, which is bad for our health. Diesel-fueled vehicles produce a significant portion of the particulate matter (PM_2.5) pollution we breathe. These particles are so small - 2.5 microns or less in diameter, which is much less than the width of a human hair - that they are easily inhaled deep into the lungs where they increase the risks of heart and respiratory diseases, especially asthma, and cancer.

Ecology, EPA, Tribes, and local clean air agencies maintain a network of air monitoring stations to measure air pollution across Washington. This network collects real-time monitoring data that shows when air pollution reaches unhealthy levels and can help guide decision-making about outdoor exposure. Because urban areas and roads with heavy truck traffic are particularly at risk of experiencing this kind of pollution, we recently launched a new air monitoring site in South Tacoma along the primary truck route that will serve the new Bridge Point warehouse facility.

This new air monitoring site is one of many projects in South Tacoma being led by Ecology with funding from the Bridge Point South Tacoma Warehouse Settlement. This work is in cooperation with community partners and local government, with input from the people most impacted living in the community near the truck routes.

Expanding our network of air monitors

Over the past 50 years, hundreds of air monitors across the state have been installed as part of the Washington Air Monitoring Network. We monitor and track hundreds of different air pollutants with a focus on EPA's six common "criteria" air pollutants, which pose the biggest threat to human health and include PM_2.5. In fact, all monitoring sites in the network measure PM_2.5.

Our monitoring network ensures outdoor air quality in all parts of the state meets federal standards called the National Ambient Air Quality Standards (NAAQS), and the information collected helps inform the public about local air quality. Anyone can view collected data on our Washington Air Quality Map and in the Air Quality Washington app, available in the Apple App store and Google Play.

"Our goal is to provide people with information they can use to help protect their health. We provide all data publicly, updated every hour, and we're always happy to answer questions about it," said Jill Schulte, environmental scientist and air monitoring coordinator for Ecology.

The Washington Air Monitoring Network is composed of both regulatory and non-regulatory air monitors. Regulatory monitors use federally approved equipment to collect regulatory data and show compliance with the NAAQS.

Other monitors, like our own SensWA devices, built and designed in-house, also provide reliable, high-quality data that helps inform public health and identify areas of concern. SensWA devices are also smaller, easier to maintain, and can be installed in more places, especially because they can use solar power.

Air monitoring expands in Tacoma

We have identified South and East Tacoma as one of 16 "overburdened communities highly impacted by air pollution" meaning that it is overburdened with health, social, and environmental inequities and is highly impacted by air pollution. Although levels of PM_2.5 are below the federal limits within this community and have declined from 2022 to 2024, at times, PM_2.5 levels have risen above federal limits. Additionally, there are higher rates of asthma, death from cardiovascular disease, and lower life expectancy compared to areas not identified as overburdened by air pollution.

At present, there are five air monitoring stations in Tacoma that are part of the Washington Air Monitoring Network (visible on the Washington Air Quality Map), with a sixth scheduled to re-launch soon by the Puget Sound Clean Air Agency in the Port of Tacoma. Three of these monitors are funded by the Bridge Point Settlement. One of these monitors - Tacoma-South Adams Street - is located near Oakland High School and has been operating for over a year. Another -Tacoma-South 56th Street - was recently installed on the roof of a local fire station in a part of town where residents had expressed some concern. Both of them are SensWA devices that run on solar power.

The third and newest air monitor funded by the settlement is located near the future Bridge Point warehouse at South 35th Street. As a regulatory air monitor, it requires a larger space in a protected fenced-off area that meets all EPA monitor-siting requirements. Placing an air monitor depends on many factors. "We consider the nearby environment and make sure that obstructions like walls, trees, or exhaust vents don't skew the data we collect," said Schulte. "No matter what the objective of a monitor is, we need to be sure that the air we monitor is representative of the air people breathe."

Settling on the location of the South 35th Street monitor was different than usual. "Usually, when deciding where to put a monitor, we're looking at where people are spending their time and where pollution levels are higher," said Schulte. "This time, we're looking ahead at the potential impact, and providing information to the community along this route for trucks serving this facility."

As an air monitoring specialist for Ecology and the primary coordinator for this new site Qianna Xu, Ph.D. knows how to navigate the many logistics required to install and maintain a site. She also knows the numerous benefits of these sites.

"People can check their air quality at any time and decide whether they want to go out and jog or not. And on a larger scale, the data we collect from both kinds of air monitoring stations can be used for other research purposes. I think that's very meaningful," said Xu.

More about our settlement with Bridge Point Tacoma, LLC

Bridge Point Tacoma's new warehouse is over 2.5 million square feet of industrial space spread across four buildings. The company purchased the land, located on a historically contaminated site, in September 2021 for $160 million. As part of a settlement agreement, the Bridge Point developer agreed to pay us $8.95 million to reduce impacts to indoor and outdoor air quality near their new warehouse.

"Our goal with these settlement funds is to support the community's priorities and facilitate actions that can provide meaningful outcomes," said Meg Bommarito, Ecology regional planner and project manager. "Our initial focus is protective measures for the neighborhood most impacted by the primary truck traffic route, and then, as we progress, we'll broaden resource access to the wider settlement area."

The new air monitoring station at South 35th Street is one of those protective measures. It launched on July 10, and is designed to monitor pollutants most associated with heavy duty diesel trucks, including PM_2.5 and nitrogen dioxide (NO₂), which are typically higher near roadways, as well as black carbon, which will indicate how much of the PM_2.5 is coming from diesel exhaust compared to other sources.

In addition to the monitoring station, we are using settlement funds on a number of activities to improve indoor air quality. This includes partially weatherizing homes along the north warehouse truck route in partnership with the Metropolitan Development Council (MDC), providing portable air cleaners for homes along the truck route and near the new warehouse facilities, and planting trees in partnership with the City of Tacoma after conducting a tree planting study to see where trees could help reduce air pollution.

"Partnerships, like the ones with MDC, the City of Tacoma, and community groups will strengthen our efforts - bolstering settlement funds and improving outcomes for the community. For instance, collaborating with Voice Tacoma Creative Media allowed us to connect directly with residents to get their input. All of this community feedback has influenced how we use settlement funds to best support South Tacoma," said Southwest Region Director Bobbak Talebi. "We will continue engaging with the community as these projects progress."