Portland, ME
Long-term air quality
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.
Portland, ME air quality summary: Portland, ME, achieves a clean air score of 85.2 and an overall grade of A. The city's annual mean for PM2.5 is 5.7. Portland has an annual PM2.5 mean of 5.7. The long-term air quality in Portland is improving, showing a positive environmental trend over recent years.
Clean Air Score
A clean air score of 85.2 and an A grade signify exceptional long-term air quality in Portland. These metrics reflect that particulate matter levels are consistently low, providing a high-quality environmental setting for the community.
🏡 What This Means for Buying
Portland's A-grade air quality is a positive feature for those evaluating the city for long-term residency. These metrics offer a factual basis for understanding the city's strong environmental standing.
Indoor Air Quality in Portland, ME
Outdoor pollution can still affect indoor air when windows are open, filtration is weak, or wildfire smoke moves in.
How to react when today's AQI changes
Use the AQI bands below to decide whether to open windows, run an air purifier, or stay indoors when pollution spikes in Portland.
AQI 0-50
GoodOpen windows: Open windows if you want fresh air.
Air purifier: No purifier needed for most homes.
Indoor activity: Normal indoor activity is fine.
AQI 51-100
ModerateOpen windows: Sensitive groups should limit open-window time.
Air purifier: Use fans or filtration if dust or pollen is bothering you.
Indoor activity: Most people can stay active indoors.
AQI 101-150
Unhealthy for Sensitive GroupsOpen windows: Keep windows closed.
Air purifier: Run a HEPA purifier in the main room and bedroom.
Indoor activity: Sensitive groups should reduce outdoor exposure.
AQI 151+
UnhealthyOpen windows: Keep windows and doors closed.
Air purifier: Run HEPA continuously and seal obvious drafts.
Indoor activity: Stay indoors as much as possible; use an N95 if you must go out.
Common indoor air concerns in Portland:
- Seasonal pollen and dust mite allergens
- VOCs from household products
Recommended action: If today's AQI reaches 101 or higher, close windows and run HEPA filtration before indoor air starts to feel smoky or stale.
Top Products for Portland Homes:
🩺 My Health Risk Assessment
See how Portland's air quality affects you and your family specifically.
Health Advice
Enjoy the outdoors! Air quality is great.
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</> Create Free Widget🏡 Property Value Impact Analysis
Between 2019 and 2024, Portland's air quality improved by 3 μg/m³. Based on NBER studies, this change correlates with a estimated 12% increase in relative property value retention.
Cleaner Alternatives in ME
🏆 Best Neighborhoods in Portland
We analyzed air quality across multiple zip codes to find the healthiest spots to live. See which neighborhoods ranked #1.
Why Portland earned a 85.2
Raw inputs, scoring weights, and data coverage for this city.
Best Time to Run
Find the cleanest hours for your run today.
Cycling Forecast
Avoid pollution spikes on your next ride.
📅 Past 30 Days Trend
Real-time daily PM2.5 AQI
🌸 Pollen Outlook
Current Seasonal Forecast
How it worksBased on current seasonal forecast data. Not a long-term pollution rating or relocation score.
Score Breakdown
| Component | Weight | Score Contribution |
|---|---|---|
| Annual Air Quality | 40% | 90.3 |
| Unhealthy Days | 25% | 100 |
| 5-Year Trend | 20% | 65 |
| Seasonal Variability | 10% | 90.5 |
| Extreme Events | 5% | 100 |
Explore More Air Quality Data
Frequently Asked Questions
About This Data
Data Sources
Historical air quality mapping and scoring are based completely on official U.S. Environmental Protection Agency (EPA) AirNow API data. 5-day AQI forecasts are provided by WAQI.
Methodology
Our Clean Air Score (0-100) is a proprietary algorithm that weighs multiple factors:
- Annual PM2.5 averages (40%)
- Frequency of unhealthy days (25%)
- 5-year pollution trends (20%)
- Seasonal variability and extreme events (15%)
Updates & Accuracy
Real-time data is updated hourly. Historical aggregate scores are recalculated monthly to reflect the latest trends. While we strive for accuracy, sensor maintenance and local conditions can affect individual readings.
Practical Advice
When AQI > 100: Sensitive groups (children, elderly, asthmatics) should limit prolonged outdoor exertion.
When AQI > 150: Everyone should avoid outdoor exercise and keep windows closed.
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Portland Air Quality FAQs
Is Portland a good fit for people who care about long-term air quality?
Portland has a clean air score of 85.2 and an overall grade of A. With a PM2.5 annual mean of 5.7, the city is an excellent choice for those prioritizing high long-term air quality.
What is the frequency of unhealthy air or long-term pollution exposure in Portland?
Portland has an unhealthy days percentage of 0. This lack of unhealthy days reinforces the city's A grade and its healthy annual PM2.5 levels.
Is air quality in Portland improving or getting worse over time?
Air quality in Portland is improving. This indicates that long-term particulate levels have been trending downward over the observed period.
Are there specific neighborhoods in Portland with better or worse air quality?
Air quality can vary between neighborhoods in Portland. For more localized detail, residents should look into neighborhood-specific or ZIP-level information.