Mercer Island air quality.
Air quality observations and historical context for Mercer Island, WA
Historical perspective
The longer view.
Annual PM2.5 concentrations · µg/m³
Regional reference: Seattle (5.7 miles away). These historical values are inherited from that location, not measured in Mercer Island.
View data table
| Year | PM2.5 |
|---|---|
| 2019 | 6.9 |
| 2020 | 8.6 |
| 2021 | 5.9 |
| 2022 | 8.3 |
| 2023 | 7.2 |
| 2024 | 5.7 |
Available history: 2019–2024. Historical scores are distinct from current AQI and do not describe today’s conditions.
Sources and scoring method ↗Local context
What this page tells you
This page combines annual PM2.5, unhealthy days, 5-year trend, and data coverage so you can compare long-term air quality, not just today's reading.
🌍 Live Air Quality in Mercer Island
Real-time pollutants resolved via none
Last 24 Hours: Mercer Island AQI Trend
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Regional Air Quality Context & Seasonal Patterns
Mercer Island is treated as a local community in WA, so the most useful signal is the long-term pollution baseline rather than a single live AQI reading. Annual PM2.5 averages 5.7 ug/m3, with roughly 0 unhealthy-air days per year, and the multi-year trend is improving. Its Clean Air Score is 85.4 (grade A), which helps compare Mercer Island with other WA cities. In Mercer Island, historical EPA observations show that pollution levels typically peak in August (averaging an index of 36), while the cleanest air conditions occur in June (averaging 23). With an extreme events rating of 100/100, Mercer Island exhibits resilient atmospheric ventilation with fewer multi-day smoke outliers. Because Mercer Island does not have its own long-running EPA station in this dataset, the report uses Seattle about 5.7 miles away as the closest proxy monitor.
Summer (Photochemical ozone & warm-season haze)
Historically lowest pollution baseline
Fine particulate matter (PM2.5) in Mercer Island is monitored for health safety. Long-term exposure to pollutants can lead to respiratory issues, making daily checks essential for active residents in WA.
Looking for cleaner air near Mercer Island?
These destinations have significantly higher historical Clean Air Scores than Mercer Island (Score: 85.4).
Anacortes, WA
Bremerton, WA
Mount Vernon, WA
Indoor Air Quality in Mercer Island, WA
Outdoor pollution can still affect indoor air when windows are open, filtration is weak, or wildfire smoke moves in.
Complete Mercer Island Home AQI & Filtration Guide
Get custom room-by-room HEPA purifier sizing, seasonal PM2.5 trends, and local home sealing recommendations.
Usually safe to open windows for fresh air.
Air purifier is optional for most households.
Normal indoor and outdoor activity is fine.
Ventilate selectively; sensitive groups should watch symptoms.
Run HEPA filtration on low if pollen, smoke smell, or traffic exhaust is noticeable.
Most people can continue normal activity; sensitive groups should keep an eye on AQI.
Keep windows closed so outdoor PM2.5 does not build indoors.
Run HEPA filtration in bedrooms and main living spaces.
Children, older adults, and people with asthma should reduce outdoor exertion.
Keep windows and doors sealed as much as practical.
Run filtration continuously; use the highest comfortable fan setting.
Stay indoors when possible and consider an N95 if you must go outside.
🛒Top Air Purifiers & Filters for Mercer Island
Given Mercer Island's air quality profile and peak pollution season in August, maintaining certified HEPA filtration indoors is an effective defense against fine particulate matter.
Levoit Core 300 True HEPA Air Purifier
Compact, ultra-quiet (<24dB), budget-friendly replacement filters.
Check price on AmazonCoway Airmega 200M True HEPA Air Purifier
Wirecutter top pick: high airflow, eco mode, washable pre-filter.
Check price on AmazonBlueair Blue Pure 311i+ Max Air Purifier
Extra carbon filtration for wildfire smoke and VOCs, smart app enabled.
Check price on AmazonCoway Airmega 400 True HEPA Air Purifier
Dual-suction Max2 filter for high smoke/pollen exposure in open spaces.
Check price on AmazonAs an Amazon Associate, Clean Air Data earns from qualifying purchases. Prices and availability shown on Amazon at time of purchase. This does not affect our air quality data or recommendations.
Health Recommendations
Most people can continue outdoor activities normally. Keep an eye on changing conditions.
Children and elderly should reduce prolonged or heavy outdoor exertion if AQI rises above 50.
Running & Outdoor Exercise Guide
Explore available hourly data before planning outdoor time in Mercer Island.
Environmental Health Dossier: Air & Tap Water in Mercer Island
Atmospheric fine particulate matter (PM2.5) and municipal drinking water contaminants represent the two primary involuntary daily exposures in any household. While HEPA filtration purifies indoor air, municipal tap water often contains invisible halogenated byproducts, heavy metals, or PFAS forever chemicals.
Mercer Island holds a historical Clean Air Score of 85.4/100. High PM2.5 requires True HEPA (H13) physical media filters without electronic ozone generation.
Municipal utility compliance focuses on legal limits, not health guidelines. Verified solid-carbon or Reverse Osmosis filters target lead, chlorine byproducts, and micropollutants.
Compare Mercer Island Air Quality
See how Mercer Island’s pollution baselines and seasonal patterns compare side-by-side.
Frequently Asked Questions about Mercer Island Air Quality
Is air quality in Mercer Island safe today?
Current air quality in Mercer Island is being monitored. Based on historical data, Mercer Island has a clean air score of 85.4. For real-time updates, check the live monitoring panel on this page.
When is air pollution highest in Mercer Island?
According to multi-year EPA observations, air pollution in Mercer Island historically peaks during August (Summer (Photochemical ozone & warm-season haze)). The cleanest air window typically occurs in June.
What should sensitive groups do during peak air pollution in Mercer Island?
Sensitive groups and outdoor runners should prioritize early morning activity before midday heat and ground-level ozone accelerate. Maintaining certified indoor HEPA filtration is an effective way to minimize personal exposure.
What is a dangerous AQI level?
An AQI (Air Quality Index) above 100 is considered unhealthy for sensitive groups, while levels above 150 are unhealthy for everyone. Levels above 300 are hazardous.
Should I wear a mask today in Mercer Island?
If the AQI in Mercer Island is above 150, an N95 mask is recommended for outdoor activities to filter out fine particulate matter (PM2.5).
Higher historical scores in WA
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