City report · Washington, United States
Seattle Air quality today
Air quality in Seattle currently reads AQI 27 (Good): Air quality is satisfactory for everyone.
Air quality right now
AQI 27
Good
- PM2.5, fine particles (µg/m³)
- 4.8
- tree cover
- 13.7%
- trees in this area
- 33.4K
- more trees needed
- 39.7K
Measured across a 1.2 mi (2 km) radius around Central Business District, Seattle, WA, USA (4.9 sq mi), from a satellite image of Sep 8, 2026. Lower AQI is better: 0–50 is Good, above 300 is Hazardous.
Seattle · AQI 27 (Good)
Seattle's tree count comes to 33,356 trees across 3.8 sq mi (9.74 km²) of land, 16 points below the 30% tree-cover level considered healthy for this area, so roughly 39,686 more trees would close the gap.
Air quality detail
Air quality in Seattle today: AQI 27, Good
Main pollutant: PM2.5 · Observed Nov 11, 05:00 local time via World Air Quality Index Project ground stations, US EPA index. Values in µg/m³.
Ground station · South Park, Seattle, Washington, USA, 5.2 mi (8.4 km) away
Health signal
Air quality is satisfactory for everyone.
PM2.5
4.8
PM10
—
NO₂
—
O₃
—
SO₂
—
CO
—
Data: World Air Quality Index Project, Washington State Department of Ecology, Air Now - US EPA
- Outdoor exercise
- A good day to be active outside
- Windows
- Open them to air the house
- Mask
- Not needed
- Air purifier
- Not needed
Over the last 7 days, the CAMS air-quality model put Seattle's daily AQI at 48 on average, from 22 on Nov 10 to an hourly peak of 83 on Nov 4.
Where Seattle stands: the most polluted cities in the world right now · the cleanest
City air guide
Why does Seattle get smoky, unhealthy air?
Right now
- Today's AQI in Seattle is 27, good, mostly from PM2.5.
- Over the past 7 days, the daily average was 48.
Wildfire smoke can drift into the Seattle area from distant fires and cause poor air for a few days to weeks [1]. In September 2020, smoke from fires in California and Oregon turned Seattle's air hazardous, the most severe rating [2]. The American Lung Association's 2026 report ranked Seattle-Tacoma 8th worst in the US for short-term particle pollution [3].
What is PM2.5, and why does smoke matter?
The main health concern in wildfire smoke is fine particles, called PM2.5 [1]. They are smaller than 2.5 microns, about 20 times smaller than the width of a human hair, and can be drawn deep into the body when you breathe [1].
King County's public health department says wildfire smoke has been found to be more toxic than other common sources of these particles [1]. Besides wildfires, fine particles also come from wood-burning stoves, diesel engines, coal-fired power plants and other sources [3].
How does wildfire smoke reach Seattle?
Wildfires may burn in remote places, but air currents can carry their smoke plumes into communities across King County [1]. The poor air can last anywhere from a few days to weeks on end [1]. The county's health department says wildfires are becoming more frequent and severe across the western US and Canada [1].
What happened in September 2020?
Overnight on Thursday, September 10, 2020, shifting winds from the southwest blew smoke from wildfires in California and Oregon into western Washington [2]. The state Department of Ecology rated Seattle's air unhealthy for everyone on Friday, September 11, and it then turned hazardous, the most severe rating [2].
Cooler weather and weaker winds slowed the fires, but the lack of wind also trapped a blanket of smoke over the Puget Sound region that weekend [2]. Seattle closed all its parks, beaches, boat ramps and playfields through Sunday to encourage people to stay inside [2].
King County said it would open a warehouse in Seattle's Sodo neighborhood, with good air filtration, as a safer place for up to 77 people experiencing homelessness [2].
How does Seattle compare with other US cities?
In the American Lung Association's 2026 State of the Air report, based on 2022 to 2024 data, the Seattle-Tacoma area ranked 8th worst in the US for short-term spikes in particle pollution [3]. Its worst county for this, Snohomish County, averaged 11.3 unhealthy days a year and got an F grade [3].
The area did better on other measures. It ranked 64th worst for ozone, a gas that forms when pollution from tailpipes and smokestacks reacts with sunlight [3]. King County, its worst county for ozone, averaged 4.3 unhealthy days a year, still an F grade [3]. For year-round particle levels, the worst county got a passing grade, below the federal standard [3].
Who is most at risk from wildfire smoke?
Wildfire smoke affects everyone's health, even people who feel young and healthy [1]. Breathing it can cause trouble breathing, irritated sinuses, headaches, stinging eyes, chest pain and tiredness [1].
People at higher risk include those who can't avoid the smoke, such as people living unsheltered or working outdoors for long periods [1]. So are people with asthma, COPD or heart disease, older adults, children and pregnant people [1].
What does King County do during smoke events?
Air pollution is measured with the Air Quality Index, or AQI, a scale that shows how much PM2.5 is in the air and the health risks that go with it [1]. Public Health Seattle and King County acts on forecast AQI levels and air quality alerts [1].
Its steps include health messages, opening cleaner air sites and advice to cut back outdoor activities [1]. At higher smoke levels, it recommends cutting strenuous outdoor activity for everyone and cancelling outdoor public events [1].
How to protect yourself in Seattle
When there is an air quality alert for wildfire smoke, King County's health department advises moving indoors and using an air filtration system [1]. Check the air quality before going out, because smoke levels can change a lot during the day [4]. Limit outdoor exercise or choose lighter activities, and move outdoor jobs to a time when the air is better [4].
Cloth masks will not protect you from wildfire smoke, but N95 respirator masks can [4]. Indoors, set up a clean air room and spend as much time in it as you can [4]. A portable air cleaner works best when it runs all the time with doors and windows closed [4]. If you have central air, use filters rated MERV 13 or higher and set the system to recirculate [4].
Avoid things that add pollution indoors, such as frying food, sweeping, vacuuming, and using gas, propane or wood-burning stoves [4].
Sources
- [1] Public Health Seattle and King County, Public Health wildfire smoke response
- [2] KUOW Public Radio, The smoke is here. Hazardous air quality in Seattle as wildfires rage (September 2020)
- [3] American Lung Association, Seattle Remains Among Ten Most Soot-Polluted Cities in the US; Bellingham Cleanest for Ozone in Latest American Lung Association State of the Air Report (April 2026)
- [4] AirNow, US Environmental Protection Agency, When Smoke is in the Air
Last reviewed . The figures in the box at the top update with every new reading; the guide itself is checked against its sources at least once a year, before the city's bad-air season.
Tree cover detail
Tree cover in Seattle: Critically low
13.7% tree cover against a 30% healthy-neighborhood target, across 3.8 sq mi (9.74 km²) of land.
Trees in this area
33,356
Target trees
73,042
More trees needed
39,686
CO₂ if planted / yr
873.1 t
Deforestation · 2001–2025
How much forest has Seattle lost?
Since 2001, the area within 10 km of Seattle has lost about 187 acres (76 hectares) of forest (about 140 football fields): 2.2% of the forest it had in 2000. Most of it (88%) was deforestation, forest cleared for good, mainly for towns and roads.
2017: satellite photo from August 2017 of a 5 × 5 km area in the city center.
- Forest lost since 2001
- 187 acres (76 ha)about 140 football fields
- Share of its forest
- 2.2%of what there was in 2000
- Cleared for good
- 164 acres (67 ha)deforestation: turned into farms, mines or towns
The worst year was 2017, when about 18 acres (7 hectares) of forest were lost.
Acres of forest lost each year
Show the figures as a table
| Year | Cleared for good | Can grow back | Total |
|---|---|---|---|
| 2001 | under 1 ha | under 1 ha | 4 acres (2 ha) |
| 2002 | 4 acres (2 ha) | under 1 ha | 4 acres (2 ha) |
| 2003 | 4 acres (2 ha) | under 1 ha | 5 acres (2 ha) |
| 2004 | 3 acres (1 ha) | under 1 ha | 3 acres (1 ha) |
| 2005 | 10 acres (4 ha) | under 1 ha | 12 acres (5 ha) |
| 2006 | 6 acres (3 ha) | under 1 ha | 7 acres (3 ha) |
| 2007 | 8 acres (3 ha) | under 1 ha | 8 acres (3 ha) |
| 2008 | 7 acres (3 ha) | 3 acres (1 ha) | 10 acres (4 ha) |
| 2009 | 6 acres (3 ha) | under 1 ha | 7 acres (3 ha) |
| 2010 | under 1 ha | under 1 ha | 3 acres (1 ha) |
| 2011 | 6 acres (3 ha) | under 1 ha | 7 acres (3 ha) |
| 2012 | 6 acres (3 ha) | under 1 ha | 8 acres (3 ha) |
| 2013 | under 1 ha | under 1 ha | under 1 ha |
| 2014 | 4 acres (2 ha) | under 1 ha | 5 acres (2 ha) |
| 2015 | 13 acres (5 ha) | 3 acres (1 ha) | 17 acres (7 ha) |
| 2016 | 13 acres (5 ha) | under 1 ha | 14 acres (6 ha) |
| 2017 | 17 acres (7 ha) | under 1 ha | 18 acres (7 ha) |
| 2018 | 10 acres (4 ha) | under 1 ha | 10 acres (4 ha) |
| 2019 | 7 acres (3 ha) | under 1 ha | 7 acres (3 ha) |
| 2020 | 9 acres (4 ha) | under 1 ha | 10 acres (4 ha) |
| 2021 | 6 acres (2 ha) | under 1 ha | 7 acres (3 ha) |
| 2022 | 11 acres (5 ha) | under 1 ha | 12 acres (5 ha) |
| 2023 | under 1 ha | under 1 ha | under 1 ha |
| 2024 | under 1 ha | under 1 ha | under 1 ha |
| 2025 | 4 acres (2 ha) | under 1 ha | 4 acres (2 ha) |
What is causing deforestation around Seattle?
- Towns and roadscleared for good88% · 164 acres (66 ha)
- Unknown causescause unknown12% · 23 acres (9 ha)
Causes for 2025 are estimates, based on what caused forest loss in the same places up to 2024.
Forest gained and lost, 2000–2020
- Forest in 2000
- 26,200 acres (10,600 ha)
- Forest in 2020
- 26,800 acres (10,800 ha)
- Overall change
- +568 acres (230 ha)more forest than in 2000
Comparing satellite maps from 2000 and 2020, the forest around Seattle grew from about 26,200 acres (10,600 hectares) to 26,800 acres (10,800 hectares), a net gain of about 568 acres (230 hectares) (+2.2%). New forest grew on about 714 acres (289 hectares), while 145 acres (59 hectares) were lost.
These 2000 and 2020 maps, from the University of Maryland, count any land with trees taller than 5 m as forest, including plantations and orchards. Forest that was cut or burned and had grown back by 2020 counts in both years, so the loss here is smaller than the yearly figures.
These figures cover everything within 10 km of the city center, a wider area than the report above, because forest is usually lost at a city's edges.
Source: Hansen/UMD/Google/USGS/NASA, Global Forest Change (GFC-2025-v1.13); causes: WRI/Google DeepMind drivers of forest loss; both CC BY 4.0, summed by Airleaf for each area. Forest gained and lost 2000–2020: Potapov et al. 2022, UMD GLAD Global Land Cover and Land Use Change, CC BY 4.0. Images: contains modified Copernicus Sentinel data. How it's measured
In the same region
Measured cities near Seattle
Same 2 km radius, same index — so they compare directly.
- Renton16.2 km
United States
- Tree cover
- 32%
- Air quality
- 27
- Kent26.1 km
United States
- Tree cover
- 36%
- Air quality
- 21
- Tacoma40.2 km
United States
- Tree cover
- 19%
- Air quality
- 38
- Everett42.6 km
United States
- Tree cover
- 23%
- Air quality
- 22
- Victoria119.4 km
Canada
- Tree cover
- 36%
- Air quality
- 36
- Saanich124.9 km
Canada
- Tree cover
- 47%
- Air quality
- 36
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Frequently asked
Questions about Seattle
What is the air quality (AQI) in Seattle right now?
The latest reading for Seattle shows an AQI of 27 (Good), measured Nov 11, 05:00 local time by the South Park, Seattle, Washington, USA ground monitoring station, 5.2 mi (8.4 km) away, via OpenAQ. The main pollutant is PM2.5. Air quality is satisfactory for everyone.
Is it safe to exercise outside in Seattle today?
At AQI 27 (Good): a good day to be active outside. Windows: open them to air the house. Masks: not needed. The reading changes through the day, so check again before a long run or ride.
What has the air quality in Seattle been like this week?
Over the last 7 days, the CAMS air-quality model put Seattle's daily AQI at 48 on average, from 22 on Nov 10 to an hourly peak of 83 on Nov 4. No day averaged above 100, the level where the air turns unhealthy for sensitive groups.
Can wildfire smoke reach Seattle from fires far away?
Yes. Air currents can carry smoke plumes from distant fires into King County, and the poor air can last from a few days to weeks.
Why was Seattle's air so bad in September 2020?
Shifting winds blew smoke from wildfires in California and Oregon into western Washington in September 2020. The state rated Seattle's air hazardous, its most severe rating, and the city closed its parks to encourage people to stay inside.
Who is most at risk from wildfire smoke in Seattle?
People who can't avoid the smoke, such as people living unsheltered or working outdoors, along with people with asthma, COPD or heart disease, older adults, children and pregnant people.
Do cloth masks protect against wildfire smoke?
No. Cloth masks will not protect you from wildfire smoke. N95 respirator masks can, and staying indoors in a room with filtered air also helps.
How does Seattle rank for air pollution in the US?
In the American Lung Association's 2026 State of the Air report, based on 2022 to 2024 data, the Seattle-Tacoma area ranked 8th worst in the US for short-term particle pollution and 64th worst for ozone.
How much forest has the area around Seattle lost since 2001?
Since 2001, the area within 10 km of Seattle has lost about 187 acres (76 hectares) of forest (about 140 football fields): 2.2% of the forest it had in 2000. Most of it (88%) was deforestation, forest cleared for good, mainly for towns and roads. Comparing satellite maps from 2000 and 2020, the forest around Seattle grew from about 26,200 acres (10,600 hectares) to 26,800 acres (10,800 hectares), a net gain of about 568 acres (230 hectares) (+2.2%). New forest grew on about 714 acres (289 hectares), while 145 acres (59 hectares) were lost.
What is the tree count in Seattle?
Seattle has an estimated 33,356 trees across the 3.8 sq mi (9.74 km²) of land measured — 13.7% tree cover, 16 percentage points short of the 30% tree-cover target set for this area.
How many more trees does Seattle need?
Seattle needs roughly 39,686 more trees to close a 16-point shortfall against its 30% tree-cover target — about 873.1 t of extra CO₂ absorbed per year once grown.
How are Seattle's air quality and tree cover measured?
Air quality is measured by ground monitoring stations near Central Business District, via OpenAQ; the 7-day trend is the Open-Meteo / CAMS model's estimate. Tree cover is measured from Sentinel-2 L2A (ESA Copernicus) via Earth Search satellite imagery at 10 m detail across a 1.2 mi (2 km) radius around Central Business District; the tree count is an estimate derived from that cover.
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