Seattle and Tacoma Air Toxics Study

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Starting in the fall of 2021, the Puget Sound Clean Air Agency will be measuring a type of air pollution called air toxics in Seattle and Tacoma. Air toxics are a group of over 400 pollutants known or suspected to cause several health problems; including cancer and birth defects, as well as damage to lungs, immune systems, and nervous systems.  

This study will gather important air quality data and help us better understand the health risks associated with air pollution. This study will look at changes in air toxics levels over time including diesel exhaust sources, wood smoke, and metal emissions in industrial areas. We will estimate potential cancer risk from these air toxics.  

Air Toxic Study Fact Sheets

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Air Toxics in the Duwamish Valley

One area where we are placing monitors is in Seattle’s Duwamish Valley. and there is an opportunity for community-directed monitoring. This part of the study included community members identifying locations of interest for monitoring. 

The study aligns with goals set by the Duwamish River Cleanup Coalition’s Clean Air Program. Recently – in a separate study – the Duwamish Valley Youth Corps partnered with the US Forest Service, and others to look at heavy metals found in moss on street trees. It’s impossible to translate the results from the moss to human health risk without air sampling, which this study will help do.  

Study Update (May 2022)

In response to community input collected in the fall of 2021, we designed the study to include more local scale air sampling in the Duwamish Valley.

Since the beginning of March 2022, we've been monitoring for metals in the air at one location – the South Seattle College (Georgetown Campus). This area was a "hot spot" in the moss study completed by the Duwamish Valley Youth Corps. Monitoring at this location is intended to help translate recent metals-in-moss study results to measurable health risks. 

Starting in May and June – when the weather is drier and more likely to include air pollution and dust – we will begin collecting samples at all of the selected monitoring sites indicated by the stars on the map below.

DV Air Toxics May update map

What To Expect

As we collect air toxics samples at the monitoring sites, Clean Air Agency staff will be setting up and regularly accessing equipment designed to measure the amount of toxics in the air at that moment in time.

We will visit each site once a week to collect the samples. The air sampler is essentially a vacuum that sucks in air at a constant rate and captures metals from the air onto a filter. Then the filters get shipped to a lab for analysis (see images below for an example).

Next Steps

Once the remaining equipment is set up, we expect to collect samples through the summer of 2022. We will then analyze the results and communicate them the community in late 2022.


Community Input

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On Tuesday, August 17th, we hosted a workshop in collaboration with the Duwamish River Clean-Up Coalition in South Park. We introduced information on air toxics, shared recent moss study results, and listened to participants' valuable input.



We invited community members to share their input input and identify locations that should be prioritized for study through an online survey. The survey was open from August 6 - September 22, 2021, and was available in English, Spanish, Somali, Vietnamese, and Khmer. 

Survey Results

The community survey results indicate community members are primarily interested in monitoring in residential areas, particularly in South Park and Georgetown. Areas of interest also included "hot spots" identified by the moss study, industrial sources, and King County International Airport. 

2021 Air Toxics Study Map_studyresults

Please contact us if you have any questions or concerns at