Snohomish County, Washington Pollution
10 top TRI facilities tracked here. PM2.5 annual mean (NAAQS 9 µg/m³ (annual)) fell modestly year over year (-12%). PM2.5 annual mean (NAAQS 9 µg/m³ (annual)) concentrations have more than halved since 2010.
FIPS 53061 · population 828,337
Where Chemicals Are Released In Snohomish County
Each red dot is one of the top TRI facilities. Size reflects 2024 total releases. County boundary outlined in blue.
Snohomish County Pollutant Multi-Year Trends
PM2.5 annual mean (NAAQS 9 µg/m³ (annual))Health riskFine inhalable particles 2.5 micrometers or smaller. They travel deep into the lungs and into the bloodstream — linked to asthma, heart disease, stroke, and premature death.
PM2.5 annual mean (NAAQS 9 µg/m³ (annual)) concentrations have more than halved since 2010.
PM2.5 24-hour 98th percentile (NAAQS 35 µg/m³ (24-hour))Health riskFine inhalable particles 2.5 micrometers or smaller. They travel deep into the lungs and into the bloodstream — linked to asthma, heart disease, stroke, and premature death.
PM2.5 24-hour 98th percentile (NAAQS 35 µg/m³ (24-hour)) concentrations have more than halved since 2010.
Lifetime cancer risk all pollutants (100 in a million (EPA elevated threshold))Health riskEPA-modeled added cancer cases per million residents from a lifetime of breathing local air toxics. EPA flags 100-in-a-million as elevated.
Single-vintage exposure modeling — EPA cadence is multi-year, so no trend line yet.
Formaldehyde ambient mean (0.077 µg/m³ (1-in-a-million URE))Health riskAn air toxic emitted by refineries, wood products, and combustion. EPA classifies it as a known human carcinogen — long-term inhalation raises cancer risk.
Single-vintage exposure modeling — EPA cadence is multi-year, so no trend line yet.
Benzene ambient mean (0.13 µg/m³ (1-in-a-million URE))Health riskAn air toxic from gasoline, refineries, and tobacco smoke. A known human carcinogen — chronic exposure is linked to leukemia and other blood cancers.
Single-vintage exposure modeling — EPA cadence is multi-year, so no trend line yet.
TRI air releases (5.1 fugitive + 5.2 stack)Health riskToxic chemicals reported by industrial facilities as released into the air — fugitive leaks plus smokestack emissions. Higher pounds means more inhaled exposure for nearby residents.
TRI air releases (5.1 fugitive + 5.2 stack) concentrations have more than halved since 2010.
TRI water releases (5.3)Health riskToxic chemicals reported by industrial facilities as discharged to surface waters (rivers, lakes, the ocean). Affects fishing, recreation, and downstream drinking-water intakes.
TRI water releases (5.3) volumes here are too small to anchor a multi-year trend; YoY movement is still shown above.
TRI land + off-site releasesHealth riskToxic chemicals released to land on-site or transferred off-site for disposal — landfills, deep-well injection, and similar. Risks groundwater contamination over time.
TRI land + off-site releases concentrations are up 78% since 2010.
Greenhouse gases (GHGRP large emitters, through 2023)Health riskGreenhouse gases reported by large industrial emitters under EPA's GHGRP, in metric tons of CO₂ equivalent. Drives climate warming and the heat-related health effects that follow.
Greenhouse gases (GHGRP large emitters, through 2023) concentrations have more than halved since 2010.
Where The Chemical Releases Are Concentrated
| Facility | City | Top chemical | Total releases | YoY |
|---|---|---|---|---|
| Cepheid - BothellDanaher CORP | Bothell | AcetonitrileHealth riskMetabolizes to cyanide in the body; high exposure causes nausea, weakness, and respiratory effects. (ATSDR) | 99k lb | +182% |
| Boeing Commercial Airplanes - EverettThe Boeing Co | Everett | Methyl isobutyl ketoneHealth riskEye, skin, and respiratory irritant; central-nervous-system depressant at high exposure. (NIOSH) | 78k lb | -4% |
| Fluid Motion LLCFluid Motion LLC | Arlington | StyreneHealth riskIARC Group 2A probable carcinogen; central-nervous-system effects from inhalation. (IARC, EPA) | 33k lb | +24% |
| C&D Zodiac INCSafran USA | Marysville | PhenolHealth riskCorrosive on contact; absorbed through skin; high exposure damages kidneys, liver, and the central nervous system. (NIOSH) | 19k lb | -13% |
| Abw Technologies | Arlington | n-Butyl alcoholHealth riskEye and respiratory irritant; high exposure causes hearing loss and central-nervous-system effects. (NIOSH) | 9k lb | +98% |
| Fluid Motion LLCFluid Motion LLC | Monroe | StyreneHealth riskIARC Group 2A probable carcinogen; central-nervous-system effects from inhalation. (IARC, EPA) | 5k lb | -36% |
| Sr Smith LLCZodiac Pool Solutions LLC | Arlington | StyreneHealth riskIARC Group 2A probable carcinogen; central-nervous-system effects from inhalation. (IARC, EPA) | 4k lb | -7% |
| US Naval Station EverettUS Department Of Defense | Everett | LeadHealth riskNeurotoxin. Even low childhood exposure impairs cognitive development; chronic adult exposure damages kidneys and the cardiovascular system. (EPA, ATSDR) | 3k lb | -36% |
| Achilles USA INCAchilles USA INC | Everett | Antimony compoundsHealth riskInhaled antimony trioxide is an IARC Group 2B possible carcinogen; respiratory and cardiovascular effects from long-term exposure. EPA MCL 6 µg/L. (IARC, EPA) | 1k lb | +37% |
| Morel Industries INC. | Arlington | Copper And Copper CompoundsHealth riskInhaled copper fumes cause metal-fume fever; chronic ingestion above EPA's 1.3 mg/L action level damages the liver. (EPA) | 750 lb | +200% |
Federal Cleanup Sites In Snohomish County
Sites on EPA's Superfund National Priorities List, plus deleted sites whose cleanup objectives EPA has finalized. Federal-facility sites (defense, DOE, etc.) are flagged separately. Each link routes to a per-site page.
| Site | City | Status | Federal facility | Primary contaminant |
|---|---|---|---|---|
| Tulalip Landfill | Marysville | DELETED | No | ArsenicHealth riskIARC Group 1 carcinogen via inhalation and ingestion. EPA MCL 10 µg/L; chronic exposure causes skin, lung, bladder cancer and cardiovascular disease. (IARC, EPA, ATSDR) |
Who Lives In Snohomish County
All block groups in Snohomish County County, WA: 828,337 residents. County disparity score for pm2.5 (fine particulate) sits below the reference (79). Why we surface this →
Low-income
People of color
Under age 5
Over age 64
- PM2.5 (fine particulate)Health riskFine inhalable particles 2.5 micrometers or smaller. They travel deep into the lungs and into the bloodstream — linked to asthma, heart disease, stroke, and premature death.81in the highest 20% nationally
- OzoneHealth riskGround-level ozone (smog) inflames the airways. Even short exposures trigger asthma attacks and worsen chronic lung and heart disease.5below the national median
- Nitrogen dioxide (NO₂)Health riskA tailpipe and combustion gas. Concentrates near busy roads and industrial sites; raises risk of airway inflammation, asthma, and lower respiratory infections in children.32below the national median
- Diesel particulateHealth riskSoot from diesel engines (trucks, trains, ports, construction). EPA classifies it as a likely human carcinogen and a major driver of childhood asthma near freight corridors.81in the highest 20% nationally
- Toxic releases (RSEI)Health riskEPA's Risk-Screening Environmental Indicators score — weights TRI chemical releases by toxicity, where they go, and how many people are nearby. Higher means greater modeled cancer and chronic-health risk.50near the national median
- Traffic proximityHealth riskPopulation-weighted distance to high-volume roads. Living close to heavy traffic raises exposure to PM2.5, NO₂, and diesel exhaust — and the cardiovascular and asthma risks that follow.58near the national median
- Lead-paint risk (pre-1960 housing)Health riskShare of housing built before 1960, when lead-based paint was common. Dust from deteriorating paint is the leading cause of childhood lead poisoning, which permanently impairs cognitive development.45near the national median
- Superfund site proximityHealth riskPopulation-weighted distance to NPL Superfund sites — the most contaminated waste sites in the country. Nearby groundwater, soil, and air can carry industrial solvents, metals, and other long-lived contaminants.56near the national median
- RMP-facility proximityHealth riskDistance to facilities holding chemicals at quantities large enough to require an EPA Risk Management Plan (refineries, fertilizer plants, etc.). These pose acute exposure risk during accidental releases.41near the national median
- Hazardous-waste site proximityHealth riskDistance to RCRA hazardous-waste handlers (treatment, storage, disposal facilities). Indicates potential exposure to industrial chemicals in air, soil, and groundwater.68above the national median
- Underground storage tanksHealth riskDensity of underground tanks (gasoline, heating oil, industrial fluids). Leaking tanks are a leading source of benzene and other volatile organic compounds in groundwater drinking-water supplies.81in the highest 20% nationally
- NPDES wastewater proximityHealth riskDistance to permitted industrial wastewater dischargers. Closer proximity raises exposure to pollutants released into surface waters used for fishing, recreation, and downstream drinking-water intakes.27below the national median
- Drinking-water non-complianceHealth riskEPA score for public water systems with health-based Safe Drinking Water Act violations. Higher means more residents on systems that recently exceeded safe limits for contaminants like lead, arsenic, or nitrate.86in the highest 20% nationally
| Indicator | Disparity score | Reading |
|---|---|---|
| PM2.5 (fine particulate) | 79 | below the reference |
| Ozone | 6 | well below the reference |
| Nitrogen dioxide (NO₂) | 34 | well below the reference |
| Diesel particulate | 75 | below the reference |
| Toxic releases (RSEI) | 45 | well below the reference |
| Traffic proximity | 55 | below the reference |
| Lead-paint risk (pre-1960 housing) | 27 | well below the reference |
| Superfund site proximity | 12 | well below the reference |
| RMP-facility proximity | 32 | well below the reference |
| Hazardous-waste site proximity | 61 | below the reference |
| Underground storage tanks | 56 | below the reference |
| NPDES wastewater proximity | 22 | well below the reference |
| Drinking-water non-compliance | 9 | well below the reference |
Source: Census ACS 2018-2022 (5-year) + USEPA-clone EJ blockgroup stats (raw indicators + EJ disparity mirror).
Co-Located Health Indicators
Modeled adult-prevalence estimates published by CDC PLACES, paired with this county's pollution and demographic context. Comparisons are ecological, not causal — pollution and disease prevalence covary at the area level, but the data does not attribute any individual's diagnosis to local exposure. How this section works →
Adult asthma (current)
CDC PLACES · 2025 release · BRFSS 2022-2023
COPD prevalence
CDC PLACES · 2025 release · BRFSS 2022-2023
Coronary heart disease
CDC PLACES · 2025 release · BRFSS 2022-2023
Diabetes (diagnosed)
CDC PLACES · 2025 release · BRFSS 2022-2023
Frequent mental distress
CDC PLACES · 2025 release · BRFSS 2022-2023
PLACES uses BRFSS-modeled small-area estimates, not individual records. Crude prevalence shown above is the local rate as published; comparators are age-adjusted vs the Washington mean and the US mean — both population-weighted across counties — so geographies with different age structures stay apples-to-apples. Sources: CDC PLACES · 2025 release · BRFSS 2022-2023.
All 18 Snohomish County Cities With TRI Data
Pollution trends and TRI 2024 pages for every tracked city in this county. Alphabetical.
- Arlington pollution· 7 facilities
- Darrington pollution· 0 facilities
- Edmonds pollution· 0 facilities
- Everett pollution· 4 facilities
- Granite Falls pollution· 0 facilities
- Index pollution· 0 facilities
- Lake Stevens pollution· 0 facilities
- Larch Way pollution· 1 facility
- Lynnwood pollution· 0 facilities
- Maltby pollution· 2 facilities
- Marysville pollution· 1 facility
- Monroe pollution· 1 facility
- Mountlake Terrace pollution· 0 facilities
- Mukilteo pollution· 0 facilities
- Snohomish pollution· 0 facilities
- Stanwood pollution· 0 facilities
- Startup pollution· 0 facilities
- Sultan pollution· 1 facility
Sources.
- EPA Toxics Release Inventory · retrieved 2026-05-07.
All sources are federal public-domain datasets under 17 USC §105. We aggregate but do not relabel; the underlying observations remain attributable to EPA.